Norton Commando 750, Commando 850 Workshop Manual

Norton Commando 850 is a high-performance motorcycle designed for both on- and off-road use. It features a powerful 850cc engine and a robust chassis that can handle a variety of terrain. The Commando 850 is also equipped with a number of features that make it easy to ride including a comfortable seat, a responsive suspension system and user-friendly controls.

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Workshop Manual
Af
orton
COMMANDO
MODELS 850 &amp; 750: INTERSTATE FROM 1970
ROADSTER
HI RIDER
INTERPOL
FASTBACK
“сс”
'S TYPE
FASTBACK L.R.
NOTE: European Type 850 MK1A variations covered in separate supplement.
1973 Copyright by Norton Villiers Ltd., Marston Rd., Wolverhampton WV2 4NW
Phone: Wolverhampton (STD 0902) 22399
Telex: 338517
Telegraphic Address: Norvil Wton Part No. 065146
FOREWORD
The purpose of this manual is to provide the necessary technical instructions to enable distributor
and dealer staff, and also enthusiastic private owners, to carry out all routine maintenance, running
repairs and major overhaul operations.
Separate sections of the manual cover major areas and, where necessary, cross references are
used to facilitate step by step dismantling and re-assembly. The manual is well provided with line
illustrations for clarity and care has been taken to ensure that each illustration fulfils a useful
purpose rather than. merely increasing manual content.
Where special service tools are necessary, they are referred to by part number in the text. An
illustrated service tools catalogue will be made available at a later stage. This catalogue will be
separate for ease of up-dating, but will be suitably sized and pierced for inclusion with this binder.
For each year from 1971, the fully illustrated parts list and Rider's Manual are available and
will further assist service operations.
To ensure repair to the same standards as used for a new Commando, it is essential to use only
genuine Norton spares available through the normal spares supply system. The main distributors for
the various markets of the world are given below :
EUROPE: Norton Villiers Europe Limited,
North Way,
Walworth, Andover,
Hampshire.
Telephone: Andover (0264) 61414
U.S.A. West of Mississippi River:
Norton Villiers Corporation,
6765 Paramount Boulevard,
North Long Beach,
California 90805.
Telephone: (213) 531-7138.
East of Mississippi River:
Berliner Motor Corporation,
Railroad Street and Plant Road,
Hasbrouck Heights,
New Jersey 07604.
Telephone: (201) 288-9696.
CANADA:
AUSTRALASIA,
NEW ZEALAND,
FAR EAST:
BRAZIL:
SOUTH AFRICA:
Quebec, the Maritime Provinces and
Central Western Canada:
Norton Villiers Canada Limited,
9001 Salley Street,
La Salle,
Province of Quebec.
Telephone : (514) 363-7066.
Ontario:
Firth Motorcycle Limited,
1857-9 Danforth Avenue,
Toronto, Ontario.
Telephone: 465-1195.
British Columbia:
British Motorcycles Limited,
4250 Fraser Street,
Vancouver 10, British Columbia.
Telephone : 876-0520.
Norton Villiers Australia Pty. Ltd.,
25 Moxon Road,
Punchbowl,
New South Wales, 2196.
Telephone : Punchbowl 02-700731.
Silvimex,
importadorae Exportadora Ltda.,
Rua Voluntarios da Patria 69,
Rio de Janeiro, G.B.
Telephone : 206-5971.
Jack's Motors (Pty.) Ltd.
115 Main Street,
Johannesburg.
Telephone : Johannesburg 217.021.
CONTENTS
INDEX
TECHNICAL DATA
CONVERSION TABLES
ENGINE/PRIMARY DRIVE
GEARBOX ..
CARBURETOR
FRAME AND ANCILLARIES
FORKS/STEERING HEAD BEARINGS
BRAKES, WHEELS AND TYRES
ELECTRICAL
ROUTINE MAINTENANCE
OVERLEAF
SECTION A
SECTION B
SECTION C
SECTION D
SECTION E
SECTION F
SECTION G
SECTION H
SECTION J
SECTION K
vu&quot; 7
Each section is laid out generally in order of disassembly and assembly ; however, use the following
index to locate any particular subject.
ENGINE
Engine “Top End”
Removing Cylinder Head
Servicing Cylinder Head. .
Refitting Cylinder Head ..
Removing Cylinder and Pistons
Servicing Cylinder and Pistons. .
Refitting Pistons and Cylinder ..
Engine “Bottom End”
Removing Crankcase Assembly from Frame ..
Dismantling the Crankcase
Crankcase Overhaul
Reassembly of Crankshaft to Crankcases
Reassembly of Crankcase Assembly to Frame
Removing Connecting Rods
Refitting Connecting Rods
Crankshaft Servicing
Engine Accessory Systems
Lubrication . .
Oil Pump ..
Servicing other Lubrication Components
Timing
Timing Cover
Assembly of Timing Side of Engine
Tachometer .. ..
Ignition (Also see “Electrical”, Section J)
Ignition Timing ..
Auto Advance and Contact Breaker
Engine Complete
Removing and Refitting Engine Complete
PRIMARY TRANSMISSION
Removing Primary Chaincase .. .
Dismantling Primary Transmission and Clutch
Assembling Primary Transmission
Clutch Operating Assembly
Chains … …
Section
C1
C2-C8, C10
C9
C11
C12
C33
C15
C16
C17
C29
C32.
са
C28
C19, C20, C27
C21
C24, C25
C22, C23
C26, C31
C30
C36
C38
C39, C40
C37
C13
C14
C34
C35
C41
GEARBOX
Description. .
Gearbox Dismantling
Inspection of Gearbox Parts
Assembly of Gearbox
Servicing Gearbox Outer Cover
Changing Countershaft Sprocket
Removing Gearbox from Motorcycle . .
CARBURETOR AND AIR FILTER
Description...
Removal and Disassembly of Carburetors
Examination and Reassembly ..
Carburetor Adjustment
Fuel Taps
Air Filter
FRAME
Removal and Refitting of Power Unit Complete
Frame Checking Dimensions
Servicing Suspension Units (Shocks)
Servicing Swinging Arm. .
Removing and Replacing Fuel Tank ..
Removing and Replacing Oil Tank
Accessory and Side Covers
‘Servicing Isolastic Mounting Assembly
T
Rear Fender
Ps
Exhaust Systems ..
FORKS
Description...
Removing and Dismantling Forks
Servicing Steering Head Bearings
Refitting Front Forks
E
D1
D2-D5
D6
D9, D10, D12
D11
D8
D7
E1
E2, E3
E4, ES
E7, EQ
E6
E10
F1, F4
F3
FD, F7
F8
F9
F10
F11
F2, F12—F17
F18
F19
G1, G2
G3, G4
G6, G7
G8
7
PE
CT RR A
ROUTINE MAINTENANCE - Ez
BRAKES WHEELS AND TIRES
Removing and Dismantling Rear Wheel
Reassembling and Refitting Rear Wheel
Servicing Disc Front Wheel
Servicing Drum Front Wheel
Rear Brake Adjustment .. ..
Front Brake Adjustment (Drum Only)
Drum Brake Overhaul
Norton-Lockheed Disc Brake ..
Tires ..
ELECTRICAL
Description. .
Charging System ..
Alternator
Rectifier
Zener Diode
Battery and Fuse .. .
Warning Light and Assimilator ..
Ignition Switch (Pre-1971)
vr г (1971 and later Models)
Coils, Capacitors (Condensers), Ballast Resistor
Contact Breaker and Auto Advance
Spark Plugs
Lighting $ystem ..
Head and Tail Lamps
Handlebar Switch Clusters
Power Take-off Socket ..
Flashing Direction Indicators
Alternating Horn Set (Police) ..
Horn Adjustment
Electrolytic Capacitor ..
Making a 1 Ohm Test Resistor ..
Wiring Diagrams
Breaking in.. .. - .. .. .. .. E.
Routine Maintenance-Introduction _..
Maintenance Table ce
Engine, Gearbox and Primary Qil Service
Swing Arm Pivot Lubrication
Front Fork Oil Changing... .. i.
Checking Hydraulic Brake Fluid Level
Checking Battery Electrolyte Level
Spark Plugs
Tire Pressure ..
Adjusting Cam Timing Chain
A
&quot;
H1, H3, H4
H2,H5
&quot;HS, H7
H8, HY
H11
H10
H12
H13
H14
J1
J2
J3
J4
JS
J8
Jo
J10
J11, J12, J13
J12
J14
J15
J16, J17, J18 sp
J19
J20
J21
J22
J23
J24
J25
J25
K1
K2
K3
K4-K9
K10
K11
K12
K13
K14
K15
K16
96,7
я
a
7
=
3
i
&ntilde;
ENGINE
Gudgeon Pin ..
Inlet Valve .. ..
Piston Oil Control Rin
Induction Manifold
Oil Sump
Muffler
Gasket. .
Engine. .
Banjo Bolt
Crankcase Drain Plug
Garter Type Seal
Mute ..
Oil Filter Gauze
&quot;CLUTCH
Clutch Lining .
Primary Chaincase ..
Clutch Operating Arm
Clutch Sprocket
GEARBOX
Gearbox
Gear Lever
Selector Fork. .
Countershaft ;
Countershaft Sprocket
Kickstarter
FRAME
Frame Rails ..
Oil Tank
Battery Tray ..
Crankcase Shield
Accessory Cover
Grab Rail
Footrest ..
Passenger Footrest ..
Prop. Stand ..
Frame ..
Swinging Arm
Suspension Unit
FORK
Front Fork
Main Tube
Fork Slider
GLOSSARY OF PART NAMES AND ALTERNATIVES
Piston pin. Small-end pin. Wrist pin.
Intake valve.
Piston scraper ring.
Inlet manifold. Intake manifold.
Oil pan. Oil reservoir. Sump tray.
Silencer. Expansion box.
Joint. Sealing washer.
Motor.
Pipe union bolt.
Sump plug.
Spring pressure seal.
Sound deadener.
Gauze strainer.
Friction plate.
Oil bath. Transmission case.
Clutch thrust mechanism.
Clutch drum. Clutch housing.
Transmission.
Change speed lever. Gearshift lever.
Change speed fork. Shift fork.
~ High sleeve gear. Output gear.
Final drive sprocket. Gearbox sprocket.
Starter pedal.
Frame tubes.
Oil reservoir.
Battery carrier.
Sump shield. Skid plate. Bash plate. Rock
guard.
L.H. side cover.
Sissy bar. Passenger handhold.
Footpeg.
Pillion footrest. Buddy peg.
Side stand. Jiffy stand.
Chassis.
Swinging fork. Pivoting fork.
Rear shock absorber. Shock.
Telescopic fork. “Roadholder’ fork.
Front suspension.
Stanchion.
Bottom member. Sliding member.
FUEL
Throttle Stop Adjuster Screw
Pilot Air Screw
Pilot Jet
Fuel Line
Fuel Tap
Air Cleaner
Fuel Tank
Petrol ..
Paraffin
ELECTRICAL
A.C. Generator
Alternator
Capacitor ..
Lens .. .. ..
Direction Indicators
Rear Lamp
Headlamp Rim
H.T. Lead
Assimilator
Contact Breaker
WHEELS AND BRAKES
Axle
Security Bolt
Brake Expander
Master Cylinder
Brake Lining ..
INSTRUMENTS
Odometer ….
Speedometer Gearbox
Tachometer ..
Idle speed adjuster
Idling screw. Volume control screw.
Idle mixture screw.
Slow running jet. Idling jet.
Petrol pipe. Gas line.
Petrol tap. Gas cock. Pet cock.
Air filter. Air box. Air silencer.
Petro! tank. Gas tank.
Gasoline.
Kerosene.
Alternator.
Rotor and stator.
Condenser.
Glass.
Flashing indicators. Turn signals. Flashers
Tail lamp. Stop/tail lamp.
Headlamp bezel. Headlamp surround.
High tension lead. Plug lead.
Simulator, Actuator. Control unit.
Points. Breaker.
Spindle.
Tire lock.
Brake cam.
Main cylinder. Reservoir.
Brake facing.
Mileage recorder.
Speedometer drive box.
Rev. counter. Engine speed indicator.
TT TET TTR ENT
- Technical Data
Technical
Data
— Technical Data
SECTION A
TECHNICAL DATA
FRAME, ENGINE MOUNTINGS AND REAR SUSPENSION UNITS
Steering head bearing type : Double sealed ball (2 off single row sealed ball)
Front engine mounting: |
Spacer length: 2:573/2-553 тп. (65:3/64-8 тт)
Bonded bush thickness: 3 in. tapering to 0-510 in. (15-87 mm tapering to 12:95 mm)
Bonded bush quantity: 2
Buffer thickness: fin. (12:70 mm)
| Buffer outside diameter : 141 in. (42:8 mm)
~ Buffer quantity: 2
Bolt size : 7-13 in. + in. x 20 UNF
Ideal free play: 0-010 in. (-254 mm)
Shim thicknesses available: -005 in, ‘010 in., ‘020 in., 030 in. (127 mm, ‘254 mm,
‘508 mm, ‘762 mm)
Rear engine mounting
Spacer length: 1:560 in./1-550 in. (39-6/39-37 mm)
Bonded bush thickness: = in. tapering to 0:410 in. (12:70 mm tapering to 10-4 mm)
Bonded bush quantity: 3
Buffer thickness: + in. (12:70 mm)
Buffer outside diameter: 1% in. (33:3 mm)
Buffer quantity : 2
Stud thread size: &sect; in. x 20 UNF 2A
Stud length: 13-00 in. (330-2 mm)
Ideal free play : 0-010 in. (-254 mm)
| Shim thicknesses available : -005 in., -010 in., -020 in, -030 in. (-127 mm, -254 mm,
4 -508 mm, :762 mm)
Bolt torque setting: 300 in./lb. (3-456 kg./mtr.)
Rear suspension units
Type — Girling : Spring/oil damped
Total length 13 inches between centres.
Spring fitted length: 8-4 in. (213-36 mm)
Spring colour code : Red/Yellow/Red (chrome spring)
Spring rate: 126 Ib. per inch
Sping free length: 8:75 in. (222:25 mm)
SPEEDOMETER GEARING
Using Dunlop 4:10 in. x 19 in. rear tyre
Rolling radius: 12:57 in. (319-3 mm)
Revs./mile : 806
2 Gearbox ratio: 15/12 1:1:25
Technical Data A -
WHEELS AND BRAKES
Front wheel
Rim size: WM2 — 19
Spokes — Drum brake wheel: Inside LH — 90&deg; head. 8 SWG swaged, :375 in. (9:5 mm) head
Outside — 90&deg; head. 8 SWG swaged, :531 in. (13:45 mm) head
Spokes — Disc brake wheel: Inner L.H. — 90&deg; head 9 SWG 270 (6-9 mm) head
. Outer L.H. — 90&deg; head 9 SWG -270 (6-9 mm) head (80&deg;bend)
Right hand — 90&deg; head 8 SWG 290 (7:35 mm) head
Wheel bearing L.H.: 17 mm x 40 mm x 12 mm
Wheel bearing R.H.: NM 17721
Bearing housing |.D.: 1-5732 in./1-5740 in. (39-96 mm/39-98 mm)
Spindle (bearing/dia.) : 0-6671/0-6670 in. (16:945/16:942 mm)
Tire size : 4-10X19
Tire pressure : 26 Ibs./psi (1-83 kg/sq. cm.). Refer “Tire Pressures” section for permissible
variation
Tire diameter (Dunlop) : 26-46 in. (672 mm)
Sectional width (Dunlop) : 4 in. (101-6 mm)
Front brake (drum)
Type: Internal expanding two leading shoe
Drum dia. : 8 in. (203-2 mm)
Lining area — total 2 Shoes: 18-69 sq. in./474-776 sq. mms
Front brake (disc)
Type: Disc — hydraulically operated
Pad type: Steel backed, moulded and bonded friction material
Pad friction area diam. : 1-65 in. (41:9 mm) |
Pad new thickness (Pad and backing together) : -38/-37 in. (9-652/9-398 mm) |
Pad minimum thickness -0625 in. (1-5875 mm) +
Disc diameter : 10-70 in. (271-7 mm) |
Disc width at friction area : 0-260/0-250 in. (6-604/6-35 mm)
Brake fluid type: Lockheed series 329 Hydraulic Fluid for disc brakes.
(Complies with U.S. Safety Standard 116).
Rear wheel
Rim size : WM2 — 19
Spokes: Rear outer: 6-093 in. long : 8/10 SWG : 90&deg; head : offset length ‘531 in. (13-45 mm)
Rear inner : 6-093 in. long : 8/10 SWG : 90&deg; head : offset length -375 in. (9-5 mm)
Wheel bearings 1971 on: Ball journal 17 mm x 40 mm x 12 mm
Sprocket bearing : NM.17721 : post 1971
Hub bearing housing I.D.: 1-5732/1 5740 in. (39-95 mm/39-97 mm)
Tire size : 4-10 x 19 in. (104-14 x 482-60) `
Tire pressure : 26 Ibs./psi (1-83 Kg/sq. cm.). Refer “Tire Pressure” section for permissible
variation
Tire diameter (Dunlop) : 26-46 in. (672-084 mm)
Tire sectional width (Dunlop) : 4 in. (101-6 mm) —
Technical Data
Rear brake
Internal drum dia. : 7-007/6-997 in. (177-8 mm)
Lining area — total 2 Shoes: 13-6 sq. in./345-44 sq. mm.
Front forks
Type: Telescopic, hydraulically damped, internal springs
Main tube O.D.: 1-3589/1:3574 in. (34-518 mm/34-480 mm)
Top bush fitted 1.D.: 1:3595/1:3604 in. (34:531/34-556 mm) —
Bottom bush O.D.: 1:4979/1-4990 in. (38-049 mm/38:075 mm)
Fork slider 1.D.: 1-:4995/1-5010 in. (38:087/38:125 mm)
Spring — No. of coils: 75% approx.
Free length: 18-687 in. (474-65 mm)
Rate : 36-5 Ib./in. (6:52 kg/cm) Red paint marked
Steering crown lug and stem
Stem diam. at bearing areas : -9839/-9835 in. (24-993/24-983 mm)
Pre 1971 — Head race adjuster nut size: 1-3125/1-3005 in. across flats (33-33/33-03 mm)
Fork tube top nut hexagon size : 1-3125/1-3005 in. (33-33/33-03 mm)
Head bearing spacer length: 5-06 in. (128-524 mm)
Fork leg capacity: 150 cc (5 fl. 0z.) each leg
Total fork movement: 6 in. (15:24 ст)
ELECTRICAL
System voltage : 12 volt — Positive earth
Alternator type: RM 21
Rectifier type: 2 DS 506
Zener diode type: Z D 715
Battery type: Norton Villiers 063244 ; Fasa 12N9-4B; PUZ5A Lucas
Battery rating: 10 AH at 10 hour rate
Coil type: 17M6
Ballast resistor type: 3 BR
Contact breaker type: 6CA (10CA later models)
Warning light assimilator type: 3 AW
Fuse rating: 35 amp (174 amp continuous rated)
Direction indicator flasher unit type: 8 FL
Bulbs: *
Headlight: Type 370 — 12 volt — 45/40 watt
Tail light/stop light: Type 380 — 12 voit — 21/6 watt, transverse offset pin
Parking light: Type 989 — 12 volt — 6 watt, coil, miniature bayonet cap
Direction indicator lights: Type 382 - 12 volt - 21 watt
Warning lights type : Type 281 — 12 volt - 2:0 watt, coil, sub-miniature
nr
Technical Data
ENGINE
Specification: 750 850
Capacity: 745 cc (45 cu. in.) 828 cc (50-5 cu. in.)
Bore: 2:875 in. (73 mm) 3-030 in. (77 mm)
Stroke : 3-503 in. (89 mm) 3-503 in. (89 mm)
Max. Torque : 48 Ib./ft. at 5000 r.p.m. (Standard) 56 |b./ft. at 5000 r.p.m.
49 Ib./ft. at 6000 r.p.m. (Combat)
Compression Ratio: 9 :1 (Standard) 83 :1
10 :1 (Combat)
Crankshaft
Material: EN16 ВЕ
Big end journal diameter : 1:7509/1:7504 in. (44-472/44-460 mm) | N
Crankcheek bolts: EN 16 S
Balance factor: 52% Dry
Permissible end Float: 0-:005-0-015 in. (+1270--3810 mm)
Pre 1972 1972 Onward
Main bearings:
Drive side : Single Lipped Roiler Special Roller (Single Lipped)
Timing side: Single Rew Ball Special Roller (Single Lipped)
All 30 mm x 72 mm x 19 mm
Connecting rods
Material: Aluminium alloy BS.L83 or 2L65 or L77
Length betwean centres : 5-877/5-873 in. (129-276/129-274 mm)
Big end eye I.D.: (Less shells cap bolted on) 1-:8950/1-8955 in. (48-133/48-145 mm)
Width at big end eye: 1:010/1-008 in. (25-65/25-60 mm) |
Rod side clearance : -013 — -016 (:330/-406 mm) . |
Rod end clearance : Less than -001 (-0254 mm) a (С,
Pistons
Material: 35.1490 — LM. .13WP
Wrist pin boss &iexcl;.D.: -6869/-6867 in. (17-447/17-442 mm)
Diameter — bottom of skirt: 2-8713/2-8703 in. (72-931/72-906 mm) (750) std. bore
3:028/3-0271 in. {76-911/76-888 mm) (850) std. bore
Piston rings
Type: Top chrome compression. Second compression.
Taper. “S.E.” oil control. Earlier models
Top ring fitted gap: ‘010 — -012 in. (-254/-305 mm)
Middle ring (taper) fitted gap: -008 — :012 in. (-203/-305 mm)
Wrist pins (Gudgeon pins)
Length: 2:438/2-423 in. (61-925 mm/61-544 mm) 750
2-559/2-544 in. (65 mm/64-619 mm) 850 В €
Diameter: 0:6869/0:6867 in. (17-447 mm/17:442 mm) o N
- Technical Data
Cylinder block
Material: Cast iron
Grade B 2:8750/2-8754 in.
3:0320/3:0325 п.
Finished size: Grade A 2-8746/2-8750 п 750 3:0315/3-0320 про
Cylinder head
Material :
Valve seat angle:
Inlet port nominal dia. :
EX. port nominal dia. :
EX. ring thread size:
Camshaft
Material :
Maximum lift — inlet
exhaust:
Base circle dia. :
Bearing journal dia. :
Camshaft bushes
Fitted 1.D. (Left bush) :
Tappets
Standard
Combat
RR 53 B
45&deg;
14 in. (28-573 mm)
13 in. (31-76 mm)
1-997 in. x 14 T.P.I
RR 53 B
45&deg;
13in.—1% in. (28-575 — 31-75 mm)
17 in. (31-75 mm)
1:997 in. x 14 T.P.I.
Fitted 1.D. (Right bush) :
(50-93 mm) (50:93 mm)
Standard Combat
EN 32 B EN 32 B
0-332 in. (8-432 mm)
0-322 in. {8:178 mm)
-885 in. (22-479 mm)
8735 in. (22-187 mm)
Pre 1972
-8750 in. (22-225 mm)
+8750 in. (22-225 mm)
Material: Cast iron Grade 14 — stellite tipped
Push rods
Material: Heat treated Dural tube “B” or “S”
Inlet — assembled length: 8:166/8:130 in. (207-416/206-466 mm)
Exhaust-assembled length: 7-321/7:285 in. (186-053/185:039 mm)
Rockers
Material : EN33
Rocker ratio — inlet: 1:13 :1
Rocker ratio — exhaust: 1:13 :1
Bore diameter: 0:4998/0-5003 in. (12:694/12-708 mm)
Adjuster thread size: 9:39 mm x 26 TPIl. Whit Form
&quot;З90 тп. (9-906 mm)
&quot;346 in. (8-788 mm)
-906 in. (23-012 mm)
-8735 in. (22-187 mm)
1972 Onward
‘8750 in. (22:225 mm)
:8750 in. (22-225 mm)
Technical Data
Rocker shaft
Diameter: -4988/-4985 in. (12-669/12-661 mm)
Valve (tappet) Clearances (engine cold)
Inlet: -006 in. (0-15 mm) (Commando 850 and 750) ; -008 in. (0-2 mm) (Combat)
Exhaust: -008 in. (0,2 mm) (Commando, 850 and 750) ; 0-010 in. (0-25 mm) (Combat)
Valve Lift Standard | Combat
Inlet: -375 in. (9:525 mm)
Exhaust: -375 in. (9-525 mm)
Inlet: :441 in. (11-21 mm)
Exhaust: -391 in. (9:931 mm)
Valve duration : Standard | Combat
(excluding
ramps) 152&deg; | 164&deg;
Valves
Material : Inlet — EN52 — Chrome plated stem
Ex. — KE965 — Chrome plated stem
Inlet — head dia. : 1:490 in. (37-846 mm)
stem dia. (plated area): 0-3115/0-3105 in. (7:912/7-886)
Exhaust — head dia. : 1-302 in (33-0708 mm)
stem dia.: 0:3115/0-3105 in. (7-912/7:886 mm)
Valve guides
Inside dia.: 0-3145/0-3135 in. (7-988/7-962 mm)
Outside dia. : 0-5015/0-50 in. (12-738/12:725 mm) 750
0:6265/0:6260 т. (15:913/15:900 тт) 850
Heat resisting washer material : Tuffnol grade ASP
Heat resisting washer thickness: 0-062 in. (1-574 mm)
Std Inlet Combat Inlet Exhaust
Valve springs
Inner — free length: 1:482 in. (37-642 mm) 1:197 in. 1:259 in. 1-222 in.
Fitted length (30-40 mm) | (31-98 mm) (31-04 mm)
Outer — free length : 1-618 in. (41-097 mm) 1-259 in. 1-32 Tin. 1-284 in.
Fitted length (31-98 mm) | (33:55 тт) | (32:61 mm) a
_ Technical Data
Valve timing (measured at -013 in. (-3302 mm)
cam lift
Inlet opens BTDC
Inlet closes ABDC
| Standard
750 and 850
Combat
50&deg;
74&deg;
Exhaust opens BBDC 82&deg;
Exhaust closes ATDC 42&deg;
Intermediate timing gear
Bush material: Phosphor bronze
Bush finished dia. : 0:5627/0:5620 in. (14-292/14-274 mm)
59&deg;
89&deg;
88&deg;
60&deg;
— Intermediate gear shaft dia. : 0:5615/0:5610 in. (14-262/14-249 mm)
Camshaft chain
Size: -375 in. x -225. Single row (Endless)
No. of links: 38
Ideal adjustment: +; in. (4-8 mm) up and down on top run of chain
Ignition timing
Fully advanced position: 28&deg; BTDC
Contact breaker
Points gap: -014/-016 in. (-35/-4 mm)
Centre bolt thread size: 1 in. x 26 T.P.l.
Mid
No Spark plug
Type: Champion N7Y (was N6Y)
Gap: -023/-028 in.
(-59—72 mm)
Carburetor Standard Commando 750
Type: Twin concentric float Amal 930 30 mm
1970
1971 1972
Main jet:
220 with early megaphone mufflers
180 with restricted megaphone
210 with modified megaphone
220 220
(210 with mute)
Needle jet:
‘107
106 106
Needle position :
Middle
Middle Middle
(Top with mute)
Throttle valve:
3 3
WE t&eacute; a ttn a
Technical Data
Carburetor — Combat
Type: Twin concentric float Amal 932 32 mm
Main jet: 230 (220 with mute)
Needle jet: -106
Needle position: Middle (Top with mute)
Throttle valve: 3 :
Carburetor — 850 |
Type: Twin concentric float Amal 932 32 mm
Main jet: 260
Needle jet: -106
Needle position: Top
Throttle valve: 31
Needle: 928/104
Choke (spray) tube: 928/107
Air filter
Element type: Pleated design impregnated paper
TORQUE SETTINGS
Cylinder head nuts and bolts (2 in.) : 360 in./Ib. 30 ft./lb. (4:15 Kg/m)
Cylinder head bolts (7% in.) : 240 in./ib. 20 ft./ib. (2-75 Kg/m)
Cylinder base nuts (3 in.) : 300 in./Ib. 25 ft./Ib. (3-45 Kg/m)
Cylinder base nuts (+; in.) : 240 in./Ib. 20 ft./Ib. (2:75 Kg/m)
Cylinder through bolt (850) : 360 in./Ib. 30 ft./Ib. (4:15 Kg/m)
Connecting rod nuts: 300 in./Ib. 25 ft./Ib. (3:45 Kg/m)
Rocker spindle cover plate bolt: 100 in./Ib. 8 ft./Ib. (1:11 Kg/m)
Crankshaft nuts: 300 in./Ib. 25 ft./Ib. (3-45 Kg/m)
Cam chain tensioner nuts: 180 in./Ib. 15 ft./Ib. (2:07 Kg/m)
Oil pump stud nuts: 180 in./Ib. 15 ft./Ib. (2-07 Kg/m)
Rocker feed banjo bolts: 180 in./Ib. 15 ft./Ib. (2:07 Kg/m)
Engine mount bolts : 300 in./lb. 25 ft./Ib. (3-45 Kg/m)
Rotor nut: 960 in./lb. 80 ft./Ib. (11:06 Kg/m)
Alternator stud nuts: 180 in./Ib. 15 ft./lg. (2:07 Kg/m)
Clutch-to-mainshaft nut: 840 in./Ib. 70 ft./lb. (9-68 Kg/m)
Mainshaft nut: 480 in./Ib. 40/50 ft./Ib. (5-50 Kg/m)
Countershaft sprocket nut: 960 in./Ib. 80 ft./Ib. (11-06 Kg/m)
Gearbox inner cover nuts: 144 in./lb. 12 ft./Ib. (1-66 Kg/m)
Top gearbox fixing bolts : 660 in./lb. 55 ft./Ib. (7-60 Kg/m)
Rear suspension unit nuts: 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Main isolastic unit bolts: 300 in./Ib. 25 ft./Ib. (3-45 Kg/m)
Fork tube top chrome nuts: 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Fork tube lower yoke pinch bolts: 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Steering head main nut (1971 — later) : 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Disc brake caliper-to-fork leg bolts: 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Disc brake caliper end plug: 312 in./Ib. 26 ft./Ib. (3:60 Kg/m)
Discs-to-hub nuts: 240 in./Ib. 20 ft./Ib. (2-75 Kg/m)
Drum brake cam fixing nuts: 360 in./Ib. 30 ft./Ib. (4-15 Kg/m)
Sidestand nut (1972 — later) : 600 in./Ib. 50 ft./ib. (6-91 Kg/m)
Zener diode nut: 24 in./Ib. 2 ft./Ib. (-28 Kg/m)
Coil mounting bracket nuts: 10 in./Ib. 1 ft./lb. (14 Kg/m)
Oil-pressure release valve: 300 in./Ib. 25 ft./Ib. (3-75 Kg/m)
_ Technical Data
GEARBOX
Ball journal. bearings:
Mainshaft (Clutch end) Ball journal 1% in. x 24 in. x &agrave; in.
Mainshaft (K/S end) : Ball journal 2 in. x 1 x 7% in.
Layshaft (Clutch end) : Ball journal 17 mm x 40 mm x 12 mm
Reductions
4th (HIGH): 1:1
Зга: 1:21 :A
2nd: 1:70:1
1st (LOW): 2-56 :1
Theoretical road speeds using various countershaft (gearbox) sprockets
Table assumes standard sprockets : Engine 26T ` e
Clutch 57T
Rear 42T
Sprocket Teeth 19 20 21 22 23
Overall Gear Ratio 4:84 4-60 4-38 4:18 3:99
6000 92 97 102 106 112
Engine
RPM 6500 99 105 110 115 121
7000 107 113 119 124 130
Overall Ratios With 19T Gearbox | With 21T Gearbox | With 22T Gearbox
Sprocket Sprocket Sprocket
4th (HIGH): 4:84 :1 4:38 :1 4-18 : 1
3rd : 5-90 : 1 5-30 : 1 510 :1
2nd: 8:25 : 1 7-46 :1 6-84 :1
1st (Low) : 12:40 :1 11-20 : 1 10-71 : 1
No. of teeth on pinions
Layshaft :
Layshaft :
Layshaft :
Layshaft :
Mainshaft :
Mainshaft :
Mainshaft
4th 14t
3rd 20t
2nd 24t
1st 28t
4th 23t
3rd 21t
: 2nd 18t
Mainshaft :
1st 14t
Technical Data
Gearbox
High gear bush O.D.: 0-9060/0-9053 in. (23-012/22-995 mm!
High gear bush 1.D.: 0:8145/0-8140 in. (20-688/20:675 mm)
High gear bush fitted !.D.: 0-8133/-8120 in. (20-657/20-625 mm)
K/S spindle bush fitted I.D.: 1:126 in./1-124 in. (28:60/28-549 mm)
Mainshaft second gear bush fitted 1.D.: 0-8125/0-8115 in. (20:637/20-612 mm)
Layshaft third gear bush fitted 1.D.: 0-8125/0-81 in. (20-637/20:574 mm)
Layshaft first gear bush fitted 1.D.: 0-6885/0-6875 in. (17-488/17:462 mm)
Footchange spindle bush, K/S case fitted |.D.: 0:6290/0-6285 in. (15-976/15-964 mm)
Camplate/Quadrant bush fitted |.D.: 0-5005/0-4995 in. (12-713/12-687 mm)
Layshaft bush 1.D.: 0:675/0:673 in. (17-145/17-094 mm)
Gearbox sprocket: 19T or 21T Standard (Alternative sprockets available — see table above)
Camplate plunger spring
Free length: 1-500 in. (38:1 mm)
Spring rate : 21 Ibs./in. (3-74 kg/mm)
Selector spindle diameter: 0-3740/0-3735 in. (9-499/9-486 mm)
Selector fork bore: 0-3755/0-3745 in. (8-537/9-525 mm)
Primary Transmission and Rear Chain
Engine sprocket no. of teeth: 26
Primary chain details 92 pitches: -375 in. x -250 in. Triple row
Rear chain detaiis : 99 pitches: 0-400 in. x 0-380 in. simple type
Clutch chainvheel no. of teeth: 57
Clutch pushrod — length: 9-813/9-803 in. (244-250/243-996 mm)
Clutch pushrod — diameter : 0-237/0-232 in. (6:01 9/5-892 mm)
Clutch operating ball diameter : + in. (12-70 mm)
Clutch operating body lock ring thread size: 414 mm x 20 TPI
Clutch type: Multi plate, diaphragm spring
Clutch friction plate no. off: 4 — fibre clutch; 5 — metal clutch
Clutch friction plate thickness: “148/:142 in. (3:759/3-:607 mm)
Clutch friction plate materiai: DON 112, fibre clutch — sintered bronze, metal clutch
Clutch centre bearing specification : Deep grove ball bearing — one dot
OD 62 mm, ID 35 mm, Width 14 mm
Corner rad 1:5 mm
Clutch adjuster dia. and thread : + in. x 20 UNF 2A
Clutch adjuster length: 0-904 in. x 0-894 in. (22:962/22-708 mm)
CAPACITIES
Fastback fuel tank capacity : 31 Imp. galls (15 litres)
L.R. Fastback fuel tank capacity : 4 galls. (18 litres) |
Roadster fuel tank capacity: GRP 21 Imp. galis (10 litres) : Steel 2% Imp. galls (11 litres)
S.S. Hi-rider fuel tank capacity: 2 Imp. galls (9 litres)
Interstate fuel tank capacity: GRP 57 Imp. galls. (24 litres) : Steel 5% Imp galls. (25 litres)
Interpol fuel tank cep&eacute;&amp;ity : No radio : 4 Imp. galls. (18 litres)
De ‘Radio insert: 31 Imp. galls. (16 litres)
Oil tank: 5 Imp./6 UY pints, 2-8 litres
Gearbox: 0:75 Imp./0:9 U.S. pints, 0-42 litres
Front forks: 160 cc (5 fl. oz.) each leg
Primary chaincase : 200 cc &oacute;n oz.)
-” Technical Data
MISCELLANEOUS DATA
Height : Fastback etc. — 40-75 (103-5 cm)
Hi-Rider only — 50% in. (127-6 cm)
Length: 27:5 in. (222 cm)
Wheelbase: 56:75 in. (144 cm)
Total weight (with oil and 1 gal. fuel) :
Roadster 422 Ib. (191:440 Kg) (Dry): 3954 Ib. (179-3 Kg)
Interstate 436 Ib. (197-749 Kg) (Dry): 410 Ib. (186:1 Kg)
Weight on front tyre (dry) : 179-7 Ib. (84-37 Kg).( [Weights for Roadster and
Interstate model similar
Weight on rear tyre (dry): 215-7 Ib. (97-5 Kg)
(For motorcycle equipped with 4:10 in. x 19 in. tyres front and rear)
Ground clearance: 6 in. (15 cm)
Width: 26 in. (66 cm)
Front brake drum diameter: 7-95 in. (20-32 cm)
Rear brake drum diameter: 7 in. (17-78 cm)
Total braking area (front) : 18-69 sq. in. (120 sq. cm.)
Total braking area (rear) : 13-60 sq. in. (88 sq. cm.) drum brake
Overall length of exhaust system (from flange at exhaust port end of pipe to tip of
muffler: 60 in. (152:4 cm) |
Exhaust system maximum diameter: 3-5 in. (8-92 cm)
Maximum theoretical road speed : 112-6 m.p.h. (181-111 K.p.h.) Standard 750 engine
122 m.p.h. (196-336 K.p.h.) 850 engine
Road speed at 1000 r.p.m. in gears (19t sprocket)
Bottom: 6:28 m.p.h. (10-106 K.p.h.)
Second : 9-46 m.p.h. (15-220 Kph)
Third: 13-18 m.p.h. (21-211 Kph)
Top: 16:09 m.p.h. (25-894 Kph)
Total movement of front forks: 6 in. (15-2 cm)
Turning circle (full circle): 17 ft. 10 in. (518:16 cm)
Gross vehicle rating : 859 Ib. (389-6 Kg) *
Centre of gravity: 193 in. (601-65 mm) above ground unladen
Seat height (nominal) : 33 — 34 in. (5384 — 863-6 mm) dependent on model
Technical Data
SPECIAL WORKSHOP TOOLS
060941 Engine sprocket (clutch hub and cam sprocket) puller
060949 Auto advance unit lock washer (for static timing)
060999 Clutch diaphragm spring tool
061015 Clutch lock tool (locks clutch body with plates removed)
064298 Rocker spindle and auto advance slide hammer
ET2003 Crankshaft timing pinion extractor
063964 Valve guide screw-type extractor and inserter
063965 Peg spanner (wrench) for wheel bearings and disc caliper
064292 Contact breaker seal and crankshaft-to-timing cover seal drift set
063968 Exhaust lockring “C&quot;” spanner
063969 Valve seat cutting tool complete
063970 Roller bearing race extractor
063971 Front Isolastic bush insertion tool complete
060942 Steering head adjustment spanner (Pre 1971)
061359 Contact breaker oil seal guide
NM12093 7% in. box spanner | (
064622 Strap wrench
Note: A separate illustrated tool list will be available shortly. ‘
NOTES
- Conversion Tables
Conversion
Tables
Conversion Tables
U.N.E.F.
Dia. No of thds.
1/4 in. 32
5/16 in. 32
3/8 in. 32
7/16 in. 28
1/2 in. 28
9/16 in. 24
5/8 in. 24
11/16 in. 24
3/4 in. 20
13/16 in. 20
7/8 in. 20
15/16 in. 20
Tin. 20
1-1/16 in. 18
1-1/8 in. 18
1-3/16 in. 18
1-1/4 in. 18
1-5/16 in. 18
1-3/8 in. 18
1-7/16 in. 18
1-1/2 in. 18
1-9/16 ins. 18
1-5/8 in. 18
1-11/16 in. 18
U.N.F.
Dia. No. of thds.
1/4 in. 28
5/16 in. 24
3/8 in. 24
7/16 in. 20
1/2 in. 20
9/16 in. 18
5/8 in. 18
3/4 in. 16
7/8 in. 14
1 in. 12
1-1/8 in. 12
1-1/4 in. 12
1-3/8 in. 12
1-1/2 in. 12
B.A.
Dia. of | Thds.
No. bolt | per inch
о | 2362 | 254
1 | 2087 | 282
2 | 1850 | 314
3 | 1614 | 34-8
4 | 1417 | 385
5 | 1260 | 43:0
6 | 1102 | 479
7 | 0984 | 52-9
8 | -0866 | 59-1
9 | -0748 | 65-1
10 | -0669 | 72-6
11 | -0591 | 81-9
12 | -0511 | 90-9
13 | -0472 | 102-0
14 | -0394 | 109-9
15 | -0354 | 120-5
16 | -0311 | 133-3
U.N.C.
Dia. No. of thds.
1/4 in. 20
5/16 in. 18
3/8 in. 16
7/16 in. 14
1/2 in. 13
9/16 in. 12
5/8 in. 11
3/4 in. 10
7/8 in. 9
1 in. 8
1-1/8 in. 7
1-1/4 in. 7
1-3/3 in. 6
1-1/2 in. 6
1-3/4 in. 5
2 in. 4-1/2
B.S.W.
Dia. of | Threads
bolt per
(inch) inch
1/4 20
5/16 18
3/8 16
7/16 14
1/2 12
9/16 12
5/8 11
11/16 11
3/4 10
13/16 10
7/8 9
15/16 9
1 8
THREADS
B.S.F.
Dia. of | Threads
bolt per
(inch) inch
7/32 28
1/4 26
9/32 26
5/16 22
3/8 20
7/16 18
1/2 16
9/16 16
5/8 14
11/16 14
3/4 12
13/16 12
7/8 11
1 10
1-1/8 9
1-1/4 9
1-3/8 8
1-1/2 8
1-5/8 8
Conversion Tables
WIRE GAUGES
No. of Imperial Standard
Gauge Wire Gauge
Inches Millimetres
1 &quot;300 7-620
2. '276 7:010
3 ‘252 6-400
4 ‘232 5-892
5 ‘212 5-384
6 192 4-676
7 176 4-470
8 160 4-064
9 144 3-657
10 :128 3-251
11 116 2:946
12 104 2-641
13 092 - 2:336
14 -080 2-032
15 ‘072 1-828
16 &cent; ‘064 1-625
17 056 1:422
18 048 1-219
19 ‘040 1-016
20 -036 ‘914
21 032 812
22 028 711
23 -024 -609
24 ‘022 -558
25 -020 508
26 -018 457
27 -0164 -416
28 -0148 375
29 -0136 345
30 ‘0124 -314
No. of Brown and Sharpe's
Gauge American Wire Gauge
Inches Millimetres
1 -289 1-348
2 258 6-543
3 229 5:827
4 ‘204 5-189
5 ‘182 4-621
6 162 4:115
7 144 3-664
8 -128 3:263
9 114 2-906
10 102 2-588
11 091 2-304
12 081 2:052
13 -072 1:827
14 ‘064 1-627
15 ‘057 1-449
16 -051 1-290
17 ‘045 1-149
18 040 1-009
19 ‘035 +911
20 -032 811
21 ‘028 ‘722
22 &quot;025 643
23 ‘023 ‘573
24 &quot;020 511
25 -018 454
26 ‘016 -404
27 -014 360
28 012 ‘321
29 011 235
30 -010 ‘254
Number | Size
| 1 -2280
2 |-2210
3 -2130
4 -2090
5 ‘2055
6 ‘2040
7 2010
8 ‘1990
9 ‘1960
10 1935
11 1910
12 1890
13 1850
| 14 |.1820
15 -1800
16 1770
17 1730
18 1695
19 1660
20 1610
21 -1590
22 -1570
23 -1540
24 ‘1520
25 1495
26 1470
DRILL SIZES (INCHES)
Letter
Size
A
‘234
‘238
‘242
&quot;246
‘250
&quot;257
‘261
| O|T|\T|UV|O| D
‘266
‘272
‘277
‘281
&quot;290
‘295
302
316
323
332
-339
348
&quot;358
'368
377
-386
-397
Number | Size
27 1440
28 1405
29 1360
30 1285
31 1200
32 1160
33 1130
34 1110
35 “1100
36 1065
37 ‘1040
38 ‘1015
39 &quot;0995
40 &quot;0980
41 -0960
42 -0935
43 -0890
44 0860
45 0820
46 ‘0810
47 -0785
48 0760
49 0730
50 ‘0700
51 ‘0670
52 ‘0635
404
N|&lt;|x|s|&lt;|c|4||2|0|v|0|2 = r|a|&lt;
413
7
- Conversion Tables
PINTS (IMPERIAL) TO LITRES
0 1 2 3 5 6 7 8
— — -568 1-136 1.705 2:273 2-841 3-841 3-978 4-546
1 142 710 1-279 1-846 2-415 2-983 3-552 4-120 4-688
1 -284 -852 1-420 1-989 2-557 3-125 3-125 4-262 4-830
3 426 -994 1-563 2-131 2-699 3-267 3-836 4-404 4-972
GALLONS (IMPERIAL) TO LITRES
| 0 1 2 3 4 5 6 7 8 9
——_mD—.&gt;
— 4-546 9.092 | 13638 | 18-184 | 22-730 | 27-276 | 31-822 | 36-368 | 40-914 | —
10 | 45-460 | 50-005 | 54-551 | 59-097 | 63-643 | 63-189 | 72-735 | 77-281 | 81-827 | 86-373 | 10
20 | 90-919 | 95-465 | 100-011 | 104-557 | 109-103 | 113-649 | 118-195 | 122-741 | 127-287 | 131-833 | 20
30 | 136-379 | 140-924 | 145-470 | 150-016 | 154-562 | 159-108 | 163-645 | 168-200 | 172-746 | 177-292 | 30
40 | 181-838 | 186-384 | 190-930 | 195-476 | 200-022 | 204-568 | 209-114 | 213-660 | 218-206 | 222-752 | 40
50 | 227-298 | 231-843 | 236-389 | 240-935 | 245-481 | 250-027 | 254-473 | 259-119 | 263-605 | 268-211 | 50
60 | 272-757 | 277-303 | 281-849 | 286-395 | 290-941 | 295-487 | 300-033 | 304-579 | 309-125 | 313-671 | 60
70 | 318-217 | 322-762 | 327-308 | 331-854 | 336-400 | 340-946 | 345-492 | 350-038 | 354-584 | 359-130 | 70
80 | 363-676 | 368-222 | 372-768 | 377-314 | 381-860 | 386-406 | 390-952 | 395-498 | 400-044 | 404-590 | 80
90 | 409-136 | 413-681 | 418-227 | 422-773 | 427-319 | 431-865 | 436-411 | 440-957 | 445-503 | 450-049 | 90
MILES TO KILOMETRES
0 1 2 3 4 _ 5 6 7 8 9
— 1-609 3-219 4-828 6-437 8-047| 9-656| 11-265 | 12-875 | 14-484 | —
10 | 16-093 | 17-703 | 19-312 | 20-922 | 22-531 | 24-140| 25-750 | 27-359.| 28-968 | 30-578 | 10
| 20 | 32:187 | 33-796 | 35-406 | 37-015 | 38-624 | 40:234 | 41-843 | 43-452 | 45-062 | 46-671 | 20
A 30 | 48-280 | 49-890 | 51-499 | 53-108 | 54-718 | 56-327 | 57-936 | 59-546 | 61:155 | 62-765 | 30
40 | 64374 | 65983 | 67-593 | 69-202 | 70-811 | 72-421 | 74-030 | 75-639 | 77-249 | 78-858 | 40
50 | 80-467 | 82-077 | 83-686 | 85-295 | 86-905 | 88-514 | 90-123| 91-733 | 93-342 | 94-951 | 50
60 | 96-561 | 98-170 | 99-780 | 101-389 | 102-998 | 104-608 | 106-217 | 107-826 | 109-436 | 111-045 | 60
70 | 112-654 | 114-264 | 115-873 | 117-482 | 119-092 | 120-701 | 122-310 | 123-920 | 125-529 | 127-138. | 70
80 | 128-748 | 130-357 | 131-967 | 133-576 | 135-185 | 136-795 | 138-404 | 140-013 | 141-623 | 143-232 | 80
90 | 144-841 | 146-451 | 148-060 | 149-669 | 151-279 | 152-888 | 154-497 | 156-107 | 157-716 | 159-325 | 90
MILES PER GALLON
(IMPERIAL) TO LITRES PER 100 KILOMETRES
AAA
BE BS&gt;WWNNI-550
ю- ю|- NI NI
LS
28:25
26:30
25-68
24-56
23-54
22:60
21:73
20:92
20:18
19-48
—— — — o —] il —e
ю|-
RI
== в — == === &laquo;а
NDP No
DION
OSPINONO
O CO) 00 CO 1 0 С) Сл Сл
ю-- [XE
—
al
N
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—
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A
o
N
N
NI
= ей == == == == == o] —
мою
сл ое &copy; N Сл 00 — 5 =) —&gt;
QU JD 00 Сл ФФ Сл 00
25 11-30 [30 9-42
251 11-08 | 304 9-26
26 10-87 [31 9-11
261 10-66 | 31: 8-97
27 10-46|32 8-83
274 10-27 | 321 8-69
28 10-09|33 8-56
281 9-91 |331 8-43
29 974/34 8-31
291 9-58 | 344 8-19
35
35%
36
367
37
37%
38
38%
39
39%
NS NN NN NO
+ N % &AElig; Сл С) AJ 00 OO
Сл + ББ 0 0 0 5 OO A
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A
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O1
TNOPDPDDD PD
“JOO=NR&Egrave;0AJ0C
“10 = $5 60 К —1 0 &copy; &copy;)
PEACE
100 &copy; &copy; = 0 &copy; БО)
OV 0 &Agrave; &agrave; &agrave; &agrave; &copy; &Agrave; O1
o
A
4:71 | 70 4:04
4:53 | 71 3:98
4:55 | 72 3-92
4:48 | 73 3:87
4:41 | 74 3-82
4:35 | 75 3:77
4:28 | 76 3:72
4:22 | 77 3:67
4:16 | 78 3-62
4:10 | 79 3:57
Conversion Tables
POUNDS PER SQUARE INCH TO
KILOGRAMS PER SQUARE CENTIMETRE
0 1 2 3 4 5 6 7 8 9
— 0:070 0:141 0-211 0-281 0-352 0-422 0-492 0-562 0-633 —
10 0-703 0-773 0-844 0-914 0-984 1-065 1-125 1-195 1-266 1-336 | 10
20 1-406 1-476 1-547 1-617 1-687 1-758 1-828 1-898 1-969 2:039 | 20
30 2-109 2-179 2:250 2:320 2-390 2-461 2-531 2-601 2:672 2:742 | 30
40 2:812 2-883 2-953 3-023 3-093 3-164 3-234 3-304 3-375 3:445 | 40
50 3:515 3:586 3-656 3:726 3:797 3-867 3-937 4-007 4-078 4-148 | 50
60 4-218 4-289 4-359 4-429 4-500 4-570 4-640 4-711 4-781 4-851 60
70 4-921 4-992 5-062 5-132 5:203 5:273 5:343 5:414 5:484 5:554 | 70
80 5:624 5-695 5-765 5-835 5-906 5-976 6-046 6-117 6-187 6-257 | 80
90 6-328 6-398 6-468 6-538 6-609 6-679 6-749 6-820 6-890 6:960 | 90
POUNDS TO KILOGRAMS
0 1 2 3 4 5 6 7 8 9
— 0-454 0-907 1-361 1-814 2-268 2:722 3-175 3:629 4-082 | —
10 4-536 4-990 5-443 5-987 6-350 6-804 7-257 7-711 8:165 8:618 | 10
20 9-072 9-525 9-079 10-433 10-886 11-340 | 11-793 | 12-247 | 12-701 13-154 | 20
30 | 13-608 14-061 14-515 14-968 15-422 15-876 | 16-329 | 16-783 | 17-237 | 17-690 | 30
40 | 18-144 18-597 19-051 19-504 19-953 20-412 | 20-865 | 21-319 | 21-772 | 22-226 | 40
50 | 22-680 23-133 23-587 24-040 24-494 24-948 | 25-401 | 25-855 | 26-308 | 26-762 | 50
60 | 27-216 27-669 28-123 28-576 29-030 29-484 | 29-937 | 30-391 | 30-844 | 31-298 | 60
70 | 31-751 32-205 32-659 33-112 33-566 34-019 | 34-473 | 34-927 | 35-380 | 35-834 | 70
80 | 36-287 36-741 37-195 37-648 38-102 38-855 | 39-009 | 39-463 | 39-916 | 40-370 | 80
90 | 40-823 41-277 41-731 42-184 42-638 43-091 | 43-545 | 43-998 | 44-452 | 44-906 | 90
FOOT POUNDS TO KILOGRAMETRES
0 1 2 3 4 5 6 7 8 9
— 0-138 0-277 0-415 0-553 0-691 0-830 0-968 1-106 1-244 | —
10 1-383 1-521 1-659 1-797 1-936 2:074 2:212 2:350 2:489 2:627 | 10
20 2:765 2-903 3-042 3:180 3-318 3:456 3-595 3-733 3-871 4-009 | 20
30 4-148 4-286 4-424 4-562 4-701 4-839 4-977 5116 5-254 5-392 | 30
40 5:530 5-668 5-807 5-945 6-083 6-221 6-360 6-498 6-636 6-774 | 40
50 6-913 7-051 7-189 7-328 7-466 7-604 7-742 7-881 8:019 8:157 | 50
60 8:295 8:434 8:572 8:710 8:848 8:987 9-125 9-263 9:401 9:540 | 60
70 9-678 9:816 9-954 10:093 10-231 10-369 | 10-507 | 10-646 | 10-784 | 10-922 | 70
80 | 11-060 11-199 11-337 11-475 11-613 11-752 {| 11-890 | 12-028 | 12-166 | 12-305 | 80
90 | 12-443 12-581 12-719 12-858 12-996 13-134 | 13-272 | 13-411 13-549 | 13-687 | 90
“e
Conversion Tables
MILLIMETRES TO INCHES
= &quot;REP
mm. 0 10 20 30 40 50 60 70 80 30
0 -39370 78740 | 1:18110 | 1-57480 | 1-96851 | 2-36221 | 2-75591 | 3-14961 | 3-5433
1 ‘03937 | -43307 82677 | 1:22047 | 1-61417 | 2-00788 | 2-40158 | 2-79528 | 3-18891 | 3-5826
2 ‘07874 | -47244 86614 | 1-25984 | 1-65354 | 2-04725 | 2-44095 | 2-83465 | 3-22835 | 3-6220
3 11811 | -51181 90551 | 1-29921 | 1-69291 | 2-08662 | 2-48032 | 2-87402 | 3-26772 | 3-6614
4 16748 | -55118 -94488 | 1-33858 | 1-73228 | 212599 | 2:51969 | 2-91339 | 3-30709 | 3-7007
5 -19685 | 59055 -98425 | 137795 | 1-77165 | 2-16536 | 2-55906 | 2-95276 | 3-34646 | 3-7401
6 -23622 | -62992 | 1-02362 | 1-41732 | 1-81103 | 2-20473 259843 | 2.99213 | 3-38583 | 3-7795
7 27559 | -66929 | 1-06299 | 1-45669 | 1-85040 | 2-24410 | 2-63780 | 3-03150 | 3-42520 | 3-8189
8 -31496 | -70866 | 1-10236 | 1-49606 | 1-88977 | 2-28347 | 2-67717 | 3-07087 | 3-46457 | 3-8582
9 35433 | :74803 | 1:14173 | 1-53543 | 1-92914 | 2-32284 | 2-71654 | 3-11024 | 3-50394 | 3-8976
MILLIMETRES TO INCHES (DECIMALS OF)
1/1000 1/100 1/10
mm. inches mm inches mm. inches
0-001 -000039 0:01 -00039 0-1 ‘00394
0-002 &quot;000079 0:02 &quot;00079 0-2 ‘00787
0-003 &quot;000118 0-03 ‘00118 0-3 ‘01181
0-004 ‘000157 0-04 &quot;00157 0-4 ‘015675
0-005 000197 0-05 &quot;00197 0-5 ‘01969
0-006 ‘000236 0:06 00236 0-6 ‘02362
0-007 ‘000276 0-07 &quot;00276 0-7 &quot;02756
0-008 ‘000315 0-08 ‘00315 0-8 ‘03150
0-009 ‘000354 0-09 &quot;00354 0:9 &quot;03543
INCHES TO MILLIMETRES (DECIMALS OF)
Tnches 0 TO 20 30 40 171000 17100 1710
0 254:0 | 5080 | 762-0 { 1016-0 inches mm, inches mm. inches mm.
1 25:4 | 279-4 | 533-4 | 787-4 | 1041-4 -001 | 0254 01 -254 1 2-54
2 50-8 | 304-8 | 558-8 | 812-8 | 1066-8 -002 | -0508 -02 -508 2 5-08
3 76-2 | 330-2 | 584-2 | 838-2 | 1092-2 -003 | -0762 03 ‘762 3 7-62
4 101-6 | 355-6 | 609-6 | 863-6 | 1117-6 -004 | -1016 04 | 1-016 4 | 10-16
5 127-0 | 381-0 | 635-0 | 889:0 | 1143-0 -005 | 1270 -05 | 1-270 5 | 12-70
6 152-4 | 406-4 | 660-4 | 914-4 | 1168-4 .006 | ‚1524 -06 | 1-524 6 | 15-24
7 177-3 | 431-8 | 685-8 | 939-8 | 1193-8 -007 | -1778 07 | 1-778 7 | 17-79
8 203-2 | 457-2 | 711-2 | 965-2 | 1219-2 -008 | 2032 -08 | 2-032 8 | 20-32
9 228-6 | 482-6 | 736-6 | 990-6 | 1244-6 -009 | -2286 -09 | 2-286 9 | 22.86
Fractions Decimals mm. Fractions Decimals mm.
1/64 | -015625 -3969 33/64 | 515625 13-0969
1/32 -03125 7937 17/32 53125 13-4937
3/64 | -046875 1-1906 AL 35/64 | 546675 13-8906
1/16 :0625 1:5875 &gt; 9/16 -5625 14-2875
5/64 | 078125 1.9844 | = 37/64 | -578125 14-6844
3/32 .09375 2-3812 9 19/32 -59375 15-0812
7/64 | -109375 2.7781 &copy; 39/64 | -609375 15-4781
1/8 125 3-1750 о 5/8 ‘625 15-875
9/64 | 140625 35719 | y 41/64 | -640625 16-2719
5/32 15625 3-9687 o 21/32 -65685 16-6687
11/64 | -171875 4-3656 = 43/64 | -671875 17-0656
3/16 1875 4-7625 D | 11/16 -6375 17-4625
13/64 | 203125 5.1594 &copy; 45/64 | 703125 17-8594
7/32 ‘21875 5.5562 | 23/32 ‘71875 18-2562
15/64 | 234375 5-9531 &copy; 47/64 | -734375 18-6531
1/4 25 63500 | &copy; | 3/4 75 19-05
17/64 | -265625 6-7469 &gt; 49/64 | -765625 19-4469
9/32 -28125 71437 | E 25/32 -78125 19-8437
19/64 | -296875 75406 | &copy; 51/64 | -796875 20-2406
5/16 ‘3125 7-9375 | &quot;M | 13/16 -8125 20-6375
21/64 | 328125 83344 | = 53/64 | -828125 | 21-0344
11/32 -34375 8-7312 &copy; 27/32 -84375 21:4312
23/64 | -359375 9-1281 ml 55/64 | -859375 21-8281
3/8 375 9.5250 | &copy; | 7/8 875 22-225
25/64 | -390625 9-9219 = 57/64 | -890625 22-6219
13/32 -40625 10-3187 | E 29-32 -90625 23-0187
27/64 | -421875 10-7156 2 59/64 | -921875 23-4156
7/16 4375 11-1125 m 15/16 -9375 23-8125
29/64 | 453125 11-5094 a 61/64 | -953125 24-2094
15/32 46875 11-9062 31/32 -96875 24-6062
31/64 | -484375 12-3031 63/64 | -984375 25-0031
1/2 5 12-700 1 25-4
_ Engine/Primary Transmission &Ccedil;
Engine
and
Primary
u
Transmission
и
— Engine/Primary Drive
i
—
ENGINE/PRIMARY DRIVE
SECTION C
The engine/gearbox/primary transmission can be
removed from the main frame as an assembly, bolted up
in the engine plates as in Section F1. Alternately, either
the engine or gearbox can be removed from the frame
as complete assemblies after dismantling the primary
transmission. For engine removal see Section C15 andfor
gearbox removal see Section D7. Unless it is specifically
required to remove the engine complete, the simplest
method is to dismantle to crankcase level for removal as
in Section C11.
SECTION C1
REMOVING CYLINDER HEAD
Commence dismantling by removing surrounding parts
as follows:
1 Release the two large knurled knobs and lift clear
4 the seat — on Fastback models lift straight up — on
“other models lift up and rearwards. Remove the
fuse from the battery negative lead.
eras
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Fig. C1 Coil Cluster lifted clear of cylinder head
2 Remove the fuel tank (see Section F9).
3 Remove the exhaust system (see Section F19).
4 Remove the carburetors with spacers {see Section
E2.
5 Lift off the spark plug caps and remove the coil
cluster complete from the frame. On * 970 models
it is secured by 2 x z in. bolts and nuts and on
1971/72 models either by 4 x ; ir. boits with
separate nuts and washers with the bolts passing
uphill or by 4 set screws with washers screwing
into captive nuts on the underside of the bracket.
The more complicated 1971/72 cluster is best tied
up to the handiebar with wire or string to keep it
clear for work on the cylinder. (See F/g. C1)
TIGHTENING SEQUENCE
Cylinder head; order of slackening and tightening
Fig. C2
6 Dismantle the cylinder head steady. Remove the
nuts from the rubber mountings first, for otherwise
the mountings will tend to revolve in the frame.
7 Remove the three + in. A.F. socket headed screws
securing the head steady to the cylinder head.
It is not necessary to remove the rocker covers at this
stage since they may be removed with the cylinder head.
During removal of the head securing bolts and nuts,
leave the front centre bolt (shown in Fig. C2) till last.
Fig. C3
5
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Engine/Primary Drive
Tilting cylinder head with pushrods held into
cylinder head.
Remove the rocker feed pipe banjo unions from
both sides of the rocker boxes and collect the cop-
per washers from both sides of the banjos. Leave
the rocker feed pipe connected to the timing case.
Remove both sparking plugs.
Remove the cylinder head securing bolts and nuts
(excepting the front centre bdlt), in opposite order
as shown in Fig. C2.
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To achieve the minimum valve lift position and
allow maximum space for removing the cylinder
head, turn the engine by revolving the rear wheel
with top gear engaged until the pistons are as near
as possible to top dead centre.
Remove the cylinder head front centre bolt and the
head sAbuld lift slightly against valve spring pres- I
sure.
|5&raquo;
Er
Technique at this stage is to lift the cylinder head and
recess the pushrods into the head as far as possible so
that the head can be slid out between the cylinder barrel
and frame tubes. Do this as follows:
13 Lift the cylinder head from either side of the motor-
cycle, support with one hand and slide the push-
rods as far as possible into the cylinder head. Fig.
C3 shows the cylinder head tilted to the rear to
facilitate the operation.
14 Withdraw the cylinder head.
=
The cylinder ‘head gasket may adhere either to the
cylinder or cylinder head. The gasket should be
removed and protected from damage since, if remaining
in undamaged condition, it may be put into further
service.
la
SECTION C2
REMOVAL OF ROCKERS
In order to gain access to the inlet valve guides, the inlet
rockers and spindles may have to be removed as follows:
1 Remove the two set screws retaining each rocker
spindle cover plate (see Fig. C4).
2 Collect the cover plate, retaining plate and gaskets
as a set. In all probability these items will adhere
to one another and need not be disturbed.
3 Use service tool 064298 to extract the rocker
spindles as shown in Fig. Cb. Heat the
cylinder head gently to ease removal and avoid
damage to head or spindles. Ensure the shaft of
the slide hammer is threaded well into the rocker
spindles then slide the weight back against the
nut sharply several times and the spindle will be
drawn out.
_ Engine/Primary Drive
4 Lift out the rockers and collect the plain and double
spring thrust washers. On each rocker the plain
thrust washer is outboard of the rocker and the
double spring washer inboard (see Fig. C4).
SECTION C3
VALVE REMOVAL AND REASSEMBLY
— The valves need to be removed during decarbonising
(as described in Section C4) or when changing valve
springs or inlet guide to stem seals. Removal of the
cylinder head (Section C1) and inlet rocker cover stud
is necessary to gain access to the valves.
DOUBLE SPRING PLAIN (THIN)
THRUST WASHERS THRUST JVASHER
Fig. C4 Rocker thrust washers and securing plates.
Proceed as follows:
1 Using a suitable overhead valve spring compressor,
(proprietary spring compressors are readily avail-
able) place the fixed jaw against the valve head
and the movable jaw against the valve collar.
Tighten down the movable jaw to compress the
valve spring and remove the split collets. Collet
removal may be facilitated by the use of a small
screwdriver or long nose pliers. +
1d
Fig. C5 Extracting rocker spindles using slide hammer 064298
Release the pressure from the compressor and
collect the valve, springs, collars and where
necessary, the inlet guide seals.
As each valve is removed, mark it in some way so
that it can be replaced in the original position.
Examine the valves for burning or damage and
grind in the cleaned up or new valves as described
in Section C7. The seats should not need to be
recut unless new valve guides have been fitted.
Check the valve springs for collapse. This can most
easily be done by comparison with new springs or
by checking free length to the dimension given in
Technical Data.
Clean all parts very thoroughly in gasoline (petrol)
and allow to dry.
Ensure that heat insulators are fitted between the
exhaust valve spring seat and cylinder head on all
engines and that insulators are also fitted at the
inlet positions on pre 1972 cylinder heads.
at
— Engine/Primary Drive
же
o
TAE
8 On all engines fitted with guides having a locating
groove adjacent to the inlet valve guide shoulder,
ensure that the inlet guide to stem seals are fitted
and located correctly.
9 With the valve spring seat in position, loose
assemble the valve (with lightly lubricated stem)
inner and outer valve spring and top valve collar.
10 Using the valve spring compressor, compress the
collar and springs and insert the split valve cotters.
11 When the collets are firmly in position in the valve
stem groove, remove the compressor. The cylinder
head is now ready to refit.
SECTION C4
DECARBONISING
After the motorcycle has been in use for some time,
carbon deposits accumulate within the combustion
chamber and exhaust ports and also the valves cease to
seal completely due to wear and a certain amount of
burning on the valve seatings. These conditions
result in a lack of compression and an increase in the
compression ratio, giving symptoms of a gradual loss of
power, poor compression and difficult starting. To
remedy these conditions, itis necessary to remove the
carbon deposits and grind the valves to their seatings
to obtain a gas-tight seal. To do so, remove the cylinder
head (Section C1) and remove the valves (Section
C3).
Unless a carbon dispersant vat is available, the carbon
must be scraped from the combustion chambers,
exhaust ports and piston crowns. Since the cylinder
head and pistons are produced from an aluminium alloy
material which is scratched easily, the carbon must only
be removed by a soft metal or hard wood scraper which
will not damage the surface. A steel scraper or screw-
driver blade must not be used. DO NOT remove the
thin ring of carbon round the top of each cylinder bore
and leave also a ring of carbon around the edge of each
piston crown. Removal of this carbon will tend to
increase the oil consumption.
The valve stems and heads should be scraped clear of
carbon but take care not to scratch the facings. Examine
the facings for deep pitting which would render the
valves unfit for re-use.
When all parts are perfectly clean and in good condition
grind in the valves and reassemble.
SECTION C5
VALVE GUIDE RENEWAL
The cast iron valve guides are a tight interference fit
in the cylinder head and can be removed and refitted
only after heating the cylinder head to a temperature of
150&deg; to 200&deg;C. A special Service Tool 063964 is avail-
able for removing and refitting the valve guides.
Proceed as follows:
1 Place the tool adaptor marked “Remover” hollow
end down over the valve guide.
‚2 Place the cranked and threaded stem through the
valve guide from the hemisphere.
3 Hold the cranked stem to prevent it turning and
screw on the handle (see Fig. C6). As the handle is
tightened the guide and cranked stem will be
pulled through into the remover body.
Caution: If guides seem difficult to remove, ensure
head is heated evenly. Do not force guides in or out of
their bores.
New valve guides are available in oversizes of +—-002 in.
+005 in, +010 in. and +-015 in. for the long-stroke
750 and +-002 in. and -010 in for the 850 engine. The
A
———1 7 afin * -: — leas -— ——————1 {pire ———. (&copy;. n
- Engine/Primary Drive
valve guide to cylinder head interference should be
‘0015 in. — :0025 in. and if there is ovality and over-
size guides are to be fitted the valve guide bores in the
head must be reamed to suit. As a matter of course use
the improved inlet guides with valve guide-to-stem
seals during re-assembly.
Fit new valve guides as follows :
4 Place the new guide in line with the bore in the
cylinder and place the adaptor marked “Replacer”
from Service Tool 063964 over the guide.
5 Place the replacer stem through the cylinder head
and bore of the valve guide and locate the abut-
ment to the valve seat.
Fit the handle and turn to pull the guide fully home
into the head. If necessary the abutment can be
prevented from turning by the use of a suitable key
in the socket provided. Be careful not to crush
the circlips on 850 guides, just pull down tightly
enough to seat.
Recut the valve seats at the points where new
guides have been fitted. This operation is des-
cribed in Section C6.
EXTRACT
GUIDE PULLED INTO
EXTRACTOR BODY
REPLACE
INSERT'BODY PUSHES
GUIDE INTO HEAD
N116
`` Fig. C6 Using valve guide tool 063964 to remove a valve guide
dl
| Engine/Primary Transmission C _
SECTION C6
RESEATING THE VALVES
After renewal of valve guides (as in Section C5) or
where the valve seats are in badly pitted condition, it is
necessary to recut the valve seats. During decarbonising
or after recutting the valve seats, the valves must be
reground.
Cutting the valve seats — Valve seat cutters, a suit-
able arbor and pilot are available under the following
Part Number: 063969
Arbor and pilot.
Valve seat cutter (45&deg;).
Blending cutter .
Before commencing to cut the seats we stress that the
essence of cutting valve seats satisfactorily is to remove
the minimum of metal and to use the cutters in such a
way as to prevent possible “chatter” in the cutting pat-
tern. Proceed as follows:
1 Assemble the cutter and pilot to the arbor.
2 Enter the pilot into the valve guide from inside the
combustion chamber hemisphere.
—
3 Applying sufficient pressure on the arbor to give a
clean cut without “chatter”, take the first 120&deg; |
cut.
4 Repeat the operation, 120&deg; at a time until the seats
are cleaned up free of any pitting.
5 Wash with gasoline (petrol) and blow clear any
displaced material.
6 Cut the other valve seats which are affected by
pitting.
SECTION C7
Grinding-in the valves — Examine the valve heads
for cleanliness and the valve stems for cleanliness,
excessive wear or pronounced scuffing. Excessive
wear or scuffing would necessitate renewal of a valve.
If the valve head facings are pitted, they can be cleaned
up on a valve facing machine though excessive
removal of material is not recommended since it would
affect the performance of the valve.
Grind the valve facings to the seats as follows :
7 Use a good quality fine grade grinding compound
and smear a little compound all round the valve
facing.
8 Drop the valve into position and using a backward
and forwards rotary motion by holding either the
valve head or valve stem with a suitable grinding
tool, lap the valve facing to the seat.
9 Lift the valve off the seat and rotate the head 180&deg;,
10 Repeat the lapping and rotating operations until
there is a uniform dull grey bedding-in pattern on
both surfaces.
11 Wash the affected areas free of grinding compound,
then assemble the valves and springs to the head
- as in Section C3.
Fig. C7
Aligning rocker spindle
Re,
12 Test the seating of the valves by supporting the
cylinder head with valves assembled, hemispheres
upwards. Pour gasoline or kerosene (petrol or
paraffin) into each inlet port and allow 20 seconds
to elapse. If the liquid has not passed the seatings
into the combustion chambers in this time, the
lapping operation has been successful. Repeat the
operation at the exhaust valves.
— Engine/Primary Transmission
SECTION C8
REFITTING ROCKERS
The rocker spindles must be positioned correctly to
allow satisfactory lubrication. It is recommended that the
cylinder head be heated to 150&deg;-200&deg;C. prior to offering
the rocker spindles, to facilitate entry and alignment.
Assembly is as follows:
1 Heat the cylinder head gently.
2 Engage a rocker spindle into the cylinder head with
flat facing rearwards on the inlet side and forwards
on the exhaust and tap it through very gently with
a soft drift until it protudes approximately - in.
(1:59 mm) through the outer boss into the rocker
cavity.
Fit the plain washer then the rocker in position.
Drive the rocker spindie part way through the
rocker and fit the double spring washer between
the other end of the rocker and the boss in the
rocker box. a
5 Centralise the spring washer and drive the
spindle through until it protrudes no more than
3 in. (9-52 mm).
6 Align the rocker spindle as shown in Fig. C7.
Note: Flat on spindle faces away-from centre of
head, towards rocker cover.
7 Drive the spindle home taking care tRat the rocker
spindle does not turn during this operation. The
spindle should be flush or fractionally below the
joint facing on the rocker box.
SECTION C9
REFITTING CYLINDER HEAD
The cylinder head should be cleaned, inspected and
overhauled as described in previous sections, and the
valves and rockers assembled. As with dismantling, the
cylinder head and pushrods should be offered as a set.
The operation is described fully below :
1 Place the cylinder head gasket in position on top
of the cylinder.
2 Turn the engine until the pistons are at top dead
centre so that there is minimum valve lift and on
assembly one pair of pushrods is fractionally
higher than the other.
3 Place the pushrods in the pushrod tunnels in the
~~ cylinder head with the inlet pushrods (that is the
longer pair) inboard and the shorter exhaust ones,
outboard.
The cupped end of each pushrod is uppermost.
4 Take the cylinder head firmly in one hand and feed
the pushrods as far into the cylinder head as
possible, holding them with the other hand. See
Fig. C3.
5 Place the cylinder head over the cylinder, forward
end downwards and allow the pushrods to drop
down the cylinder barrel pushrod tunnels.
Note that the pushrods cannot do other than locate
on the cam followers at the lower end.
6 Starting with the pair of pushrods which are
slightly higher, engage the tops of the pushrods to
the rocker ball ends as the cylinder head is
lowered. Use an implement such as a thin screw-
driver through the exhaust rocker box to guide the
~ pushrods into position as shownin Fig. C8. Having
engaged the first pair of pushrods engage the
second pair in a similar manner.
The cylinder head is ready to be secured. The tightening
sequence is shown in Fig. C2.
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a
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10
11
12
13
-&raquo; ru
14
15
?
Fit and tighten down the short cylinder head boit
with its washer — this bolt should be inserted
down through the cylinder head fins to the centre
front position. The cylinder head should be pulled
down to the gasket against valve spring pressure
using this bolt.
Check that all four pushrods are correctly engaged
to the ball ends of the rocker arms. (
If pushrod engagement is correct, fit the four bolts
. with washers on either side of the sparking plugs,
followed by a long sleeve nut under each exhaust
port and a short nut under the inlet ports, (these
are without washers) and 2 +&amp;% in. nuts and
washers on the studs (no's 9 and 10 in Fig. C2)
which seal the joint by the pushrod tunnel. There
are no washers on the nuts fitted from beneath the
cylinder head.
Finally tighten the cylinder head bolts and nuts in
the order shown in Fig. C2. The torque settingsare :
Cylinder head bolts and nuts $ in: 30 Ibs./ft.
(3-68 Kg/m).
Cylinder head bolts +; in. :20 165. fit (2:75 Kg/m)
Adjust “ rocker cle&aacute;rances &aacute;s described in
Section C10. |
Using new sealing gaskets only if the originals are
‘unfit for further use, refit the inlet and exhaust
rocker covers and” secure with the blind nuts.
There is a washer only at the inlet rocker cover
nut. -
Refit the carburettors with spacers as described in
Section ES, and refit the sparking plugs to avoid
‘washers being dropped into the engine during the
next operation.
Refit the cylinder head steady as a reversal of the
| dismantling procedure.
Reconnect the rocker feed pipe banjos at the
cylinder head using copper washers at each side
of the banjos. Take care that the plastic part of the
rocker pipe is clear of the rocker boxes, cylinder
head and head steady.
16 Refit the coil cluster to the frame as a reversal of
the dismantling procedure and connect the spark
plug caps.
17 - Reconnect the low tension leads from the contact
breaker to the main harness. These leads are
coloured white/black and yellow/black and should
be connected colour to colour. The standard
assembly procedure is white/black to right cylinder
and yellow/black to left cylinder.
18 Refit the exhaust system (Section F1 9).
19 Refit the fuel tank (Section F9) and connect the
fuel lines. |
&deg; 20 Refit the seat and secure with the knurled side
nuts.
21 Refit the fuse.
SECTION C10
ROCKER CLEARANCES
It is essential for the correct valve to rocker clearances
to be maintained to prevent excessively noisy operation
and subsequent wear or conversely to prevent insuffi-
cient clearances, a loss of compression and burning of
the valves and seats. After checking clearances at the
time of the first free service, the clearances should be
checked and corrected as necessary at 2500 mile
(4009 Km) intervals. To provide sufficient room&quot;at the
rocker boxes for satisfactory checking, the fuel tank
should be removed as in Section F9.
The correct rocker clearances are as below, checked
with the engine cold:
Standard Com- Inlet
‘mando Engine Exhaust
(750 and 850) .
Combat Engine | Inlet
| Exhaust
0-006 in. (0-15 mm)
0-008 in. (0-2 mm)
0-008 in. (0:2 mm)
0-010 in. (0-25 mm)
Engine/Primary Transmission C e
—
TN A
. г ' !
1
Engine/Primary Transmission C
Proceed to check rocker clearances as below :
1 Remove the two exhaust and one inlet rocker
covers.
2 To facilitate rdtating the engine, remove both
sparking plugs. |
ROCKER
ADJUSTER B
“LOCKNUT A e 7
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+
Fig. C9 Checking valve clearances’: Es
3 Rotate the engine, either by the kickstart or by
turning the rear wheel forwards with fourth gear
engaged, until the left side inlet valve is fully
open. |
4 Using the correct feeler gauge (see table above for
thickness) check the rocker clearance of the right
side inlet valve. Fig. C9 shows the point where
the feeler gauge is inserted. | &amp;
5 If the clearance is correct i.e. the feeler gauge just
nips, proceed to check the next valve as in (7). If
gauge will not enter or if it does not nip, adjust as
in (6).
6 Referring to Fig. C9, slacken the adjuster locknut
(A) and screw out the adjuster (B) two turns.
Place the feeler gauge between the adjuster and
end of the valve stem and screw the adjuster in
until it just nips the feeler gauge. Tighten the lock-
nut and withdraw the gauge which should not be
gripped tightly but should slide relatively easily
-from the gap. This clearance is now correct.
— Fig. C10
%
7 Rotate the engine until the right side inlet valve is
fully &oacute;pen and adjust the left side inlet valve in a
similar manner. |
8 Adjust the right side and left side exhaust valves: Ru В
in the same sequence but using a feeler gauge i
accardance with the table of clearances.
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SECTION C11 10%
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of
REMOVING CYLINDER AND PISTONS
Remove the cylinder head as detailed in Section C1.
The cylinder is then removed as follows:
1 For the 850, remove the four through-bolts and
release the five cylinder base nuts. The 750 engine
has nine base nuts that should be removed. It will
be necessary to raise the cylinder so that the nuts
will clear the fins. All nuts have washers except
the front centre one. Be very careful that all nuts
and washers are removed before the cylinder is
lifted off.
-
At this stage the engine may be decarbonized as in
Section C4 or the cylinder, pistons and piston rings
given attention. В Ш Во
Support connecting rods to prevent damage against
crankcases
2 Commence lifting the cylinder off the base studs
and prepare to support the connecting rods as the
cylinder is lifted clear of the pistons. In Fig. C10 a
suitable implement has been inserted between the
refitted cylinder through bolts (or studs other
than on 850 models) to prevent the connecting
rods and pistons falling against the crankcase
mouth. Any damage to the connecting rods could
result in failure of the rods at a later stage of use.
3 . Place a piece of clean non-fluffy cioth over the
crankcase mouth to prevent foreign matter entering
the crankcase mouth.
4 Remove one circlip from each wrist pin (gudgeon
pin). |
5 Before removing the piston, support the body
(Fig. C11) shows the piston body being supported
by a second operative) and push out the first wrist
(gudgeon) pin, then the second, using a suitable
sized implement such as an aluminium drift.
Supporting piston body whilst pushing out
Fig. C11
gudgeon pin
SECTION C12
CYLINDER REBORING AND OVERSIZE
PISTONS
After considerable mileages, or on engines where air
filtering has been inefficient or oil changes neglected,
wear may be expected on the cylinder bores or pistons.
The maximum degree of wear may be expected to occur
at the top front and rear areas of the cylinder bores.
Similariy, the maximum wear will take place on the front
and rear faces of the pistons. Measure the cylinder bore
diameter front and rear within + in. (12:70 mm) of the
top of each bore and again front and rear at a point in
the bore below the piston ring swept area. If the bores
are in acceptable condition, the difference between the
measurements should not exceed 0:005 in. (+1270
mm).
An alternative (but less accurate) method of measure-
ment is to place one compression ring in the bore,
approximately 1 in. (12:70 mm) from the top and
measure the ring gap wit feeler gauges. Place the ring
lower in the bore below the piston ring swept area and
again measure the gap. Subtract the second reading
from the first and divide by three to arrive at the
diameter wear. The amount of wear should not exceed
0-C05 in. (+1270 mm).
Excessive wear will necessitate reboring and the fitting
of oversize pistons which are available in oversizes of
+ 0-010 in. + 0-020 in. (and + 0-030 and + 0:040 in.
for the long-stroke 750 only). Bore measurements are
listed below :
750
STANDARD:
+-010 in. oversize
2-875 in. (73-025 mm)
2:885 in. (73-279 mm)
2:895 in. (73-533 mm)
2-905 in. (73-787 mm)
2:915 in. (74-041 mm)
4-020 in. oversize
+030 in. oversize
+-040 in. oversize .
850
STANDARD:
+-010 in. oversize
3:032 in. (77-013 mm)
3-042 in. (77-267 mm)
+020 in. oversize 3-052 in. (77-521 mm)
Engine/Primary Transmission &Ccedil; _
— Engine/Primary Transmission C
SECTION C13
REMOVING PRIMARY CHAINCASE
To remove the engine or gearbox from the mounting
plates or from the frame it is necessary to dismantle the
primary transmission completely but the engine/gearbox
transmission assembly can be removed from the
frame as a single unit.
Dismantle the outer primary chaincase as follows :
——
1
2
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Remove the three nuts and plain washers securing
the left hand foot rest complete with brake pedai
and stop switch. It is unnecessary to disconnect
either the stop lamp leads or the rear brake cable
and the pedal assembly may be allowed to hang
down clear of the primary chaincase.
Place a sufficiently large drain tray beneath the
chaincase to receive all the chaincase lubricant.
There is no drain plug to the chaincase thus as the
chaincase joint is parted, the chaincase will drain
very quickly.
Remove the centre sleeve nut which secures the
outer chaincase and by rocking the chaincase
slightly to clear the locating dowels top and
bottom, lift the outer chaincase ciear.
Na
Fig. C12 Removing rotor nut wh:lst applving rear brake to
prevent movement
SECTION C14
DISMANTLING PRIMARY TRANSMISSION
AND CLUTCH
Whilst removing either the clutch or the engine sprocket,
the transmission should be prevented from turning by
placing the rear brake pedal and left hand foot rest
assembly loosely in position and applying the rear brake
fully. Proceed with dismantling as follows:
1
Using a suitable sized socket wrench in. Whit. &cent;n
the alternator rotor nut, remove the rotor nut as
shown in Fig. C12.
As the rotor nut is removed, collect the fan disc
washer from behind. -
Remove the alternator stator. This is secured by
three nuts and plain washers. As the stator is
removed, it may be left hanging on the stator lead
whilst the two snap connector terminals are dis-
connected beneath the air box.
At this stage remove the alternator rotor which is
keyed to the.engine crankshaft: If the rotor should
prove to be extremely tight on the engine crank-
shaft, slight pressure may be applied from behind
equally, Using twc flat section tyre levers Remove
the rotor key, packing collar and shims from the
engine shaft.
Remove the three stator spacers from the stator
mounting studs on the chaincase.
Slacken the clutch push rod adjuster nut and
remove the adjuster and nut altogether.
In order to dismantle the clutch, a compressor tool
part number 060999 is needed for the diaphragm
spring of the clutch. The tooi is shown in use in
Fig. C13. Note that the tool has been screwed into
the adjuster hole in the spring centre. The centre
bolt must be lightly tightened and must be at least
+ in. engaged into the diaphragm spring centre.
Now place a spanner on the withdrawal nut as
shown in Fig. C13. Turning clockwise will tighten
the withdrawal nut until pressure has been
released from the diaphragm spring and the soaring
Is completely free to rotate.
'Engine/Primary Transmission C.
8 When the spring is compressed and free to rotate 11
and using ascrewdriver blade as shown in Fig. C14,
lift the first end of the diaphragm spring clear of
the circlip groove in the housing and commence
to peel the circlip away from the groove.
9 The compressor tool and diaphragm spring should
now be lifted clear as a pair.
It is not necessary to remove the tool from the dia-
phragm spring. If it is desired to remove the tool from the
diaphragm spring, support the centre bolt to prevent it
turning and slacken off the withdrawal nut to relieve all
spring pressure. If this is not done there is a grave risk
of the spring being released suddenly from the tool
with possible injury.
12
13
14
Fig. C13 Diaphragm spring compressor too! 060999 in use
10 Fit clutch tool 061015 over hub and remove the
clutch centre nut and washer (and tab washer
fitted on later models. Note that the tab washer
can be fitted to advantage on all Commando).
Alternatively the clutch can be held by fitting the
rear brake pedal loosely into position and applied
while the nut is slackened.
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Prepare to remove the engine sprocket, primary
chain and remainder of the clutch as a set. This
necessitates the use of engine sprocket puller,
part number 064297 assembled to the sprocket
and engine crankshaft as shown in Fig. C15.
It is essential that the side bolts are screwed into
the sprocket at least 1 in. prior to tightening of the
centre bolt for extraction purposes for otherwise
the thread may be stripped. Now tighten the
centre bolt of the puller against the crankshaft and
shock the side of the sprocket using a soft metal
‘drift and hammer, whereupon the taper joint
between the sprocket and shaft should be broken.
For convenience, remove the engine sprocket
puller from the sprocket and lift away the remainder
of the clutch, the engine sprocket and primary chain
as a set as shown in Fig. C16, feeding the stator
between the runs of the primary chain.
It will be noted that clutch and engine sprocket
alignment has beenensured by the use of a collar
and spacers over the gearbox mainshaft and these
items should be collected and stored carefully for
use during re-assembly. Note that if the crank-
shaft, engine sprocket, mainshaft or clutch have
been renewed, re-alignment may be necessary.
In order to remove the inner primary chaincase the
three set screws with tab washers should be
removed. Before attempting removal, tap the tabs
clear of the set screw heads, remove the set
screws then the tab washers and lift clear the
inner primary chaincase. The chaincase may be
“removed with or without the stator, whichever is
desired. The stator is secured to the-chaincase at
this stage only by the main cable passing through |
the grommet in the back of the chaincase.
— Engine/Primary Transmission C
15 Collect the spacer washer or washers used on the
centre stud. Note that if a sufficient quantity of oil
has drained into the crankcase prior to stripping,
oil will tend to run from the chaincase securing
holes in the crankcase, thus it is recommended that
the bolts be replaced finger tight in the lower holes.
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Fig. C16 + Removing engine sprocket clutch and primary chain
as a set
ve
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SECTION C15
REMOVING CRANKCASE ASSEMBLY FROM |
FRAME |
В “ Removal of the crankcase assembiy from the frame is |
&raquo; most easily achieved by removing the remaining |
— ancillary equipment then taking out the front mounting !
Fig. C14 Using a screwdriver blade to peel circlip away from complete and draining all remaining oil from the
housin
9 | crankcase.
La : The full routine is as follows :
| 1 Disconnect the tachometer cable at the front of
1 я crankcase.
2 Remove the rocker feed pipe from the back of the
crankcases and collect the copper washers.
3 Remove the gear indicator:and set screw. i
Remove also the gear-pedal which is secured by
one bolt. EN
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‘pipe clear of the oil i
Im
4 Push the crankcase breath
tank. 3
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5 Place a large capacity “drain tray beneath the
crankcases. 5
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(5 | 6 Remove the oil pipe junction block from the rear
= Fig. C15 Use of engine sprocket puller 064297 of the crankcase, N
Engine/Primary Transmission C
7 Slacken the large hexagon sump filter on the
bottom of the crankcases. This filter requires the
use of a Z in. Whit. (or 1% in. AF) spanner.
Service tool NM 12093 is suitable. (A smaller
drain plug was fitted to 1972 and '73 750's only.
Similar instructions apply.)
8 Remove the large diameter centre bolt of the front
mounting from the timing side. This will necessi-
tate aligning the flats on the bolt head to clear the
timing case. To facilitate removal of the front
mountings from between the frame down tube
brackets, slide back the gaiter at the left hand side
so that the spacer, end cap and shims can be
withdrawn. Remove the two nuts from the timing
side of the engine mounting studs, then pull out
the studs complete with remaining nuts from the
drive side. The front mounting can then be pulled
“free away from the crankcases.
9 Remove the bottom rear crankcase-to-engine-
plate bolt and the bottom centre stud. Extract the
bottom stud by lifting the crankcase assembly
slightly so that the stud clears the frame rails.
10 The sump filter can now be removed completely
and the engine lifted vertically to enable the
crankcase to be drained. Fig. C17 shows the
crankcases supported by a bar from below whilst
the sump filter is removed with the fingers after
slackening at an earlier stage.
F
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| | { ( }
LARGE DRAIN PLUG UP TO 197
SMALL DRAIN PLUG POST - 1972
LARGE DRAIN PLUG REINTRODUCED 1973 *850”
Fig. C17
Showing crankcases supported by a bar to remove
sump filter
11 Remove the top rear engine to engine plate nut,
supporting the weight of the crankcase as the stud
is pulled out.
12 The crankcase assembly is now free to be removed
from the mounting plates as shown in Fig. C18.
Further dismantling of the engine can proceed
more conveniently on the bench after removal.
Removal of the crankcase assembly from mounting
plates
SECTION C16
DISMANTLING THE CRANKCASES
The majority of the work on the crankcases can be
carried out best with the crankcase mounted in a plain |
jaw vice as shown in Fig. C19.
Fig. C18
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Fig. C19 Showing crankcases mounted in a plain jaw vice for
ease of handling _
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. Engine/Primary Transmission €
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The basic order of dismantling is to remove the timing
cover and dismantle the camshaft chain and sprockets,
then the oil pump. At this stage the crankcases should
be removed from the vice to be parted for removal of
the crankshaft. The full routine is described below :
1 If the remaining crankcase bottom bolt is still
fitted, this should be removed to allow the crank-
case to be mounted securely in a vice.
2 Remove the two contact breaker cover screws and
lift away the C.B. cover.
3 Remove the contact breaker cam centre bolt,
serrated washer and plain washer.
A
4 Using service tool 064298 as shown in Fig. C20,
screw the shaft into the contact breaker cam then
slide the weight back sharply several times until
the cam is lifted off the camshaft taper. It is
unnecessary to remove the contact breaker plate
from the timing cover at this stage unless so
desired.
5 Remove the timing cover screws and part the
joint between the timing cover and crankcase by
a careful tap from behind the pressure release
valve body using a hide hammer.
Fig. C20 Removing contact breaker cam using slide hammer
064298.
6 Lift the timing cover away, withdrawing the
contact breaker lead from the timing case. It may
be necessary to turn one of the snap connector
bullets backwards so that the lead feeds through
the case, one snap connector bullet at a time.
Remove the two nuts securing the oil pump. The
oil pump may be quite tight on its studs and in
these circumstances it is advantageous to turn the
oil pump drive wheel nut so that the oil pump
will pull itself away along the worm drive. This
operation is shown in Fig. C217.
Fig. C21 Using a spanner to turn the:0il pump drive wheel nut
and remove the pump
Remove the oil pump driving worm from the
crankshaft with its integral left hand threaded nut.
To achieve this it is necessary to stop the crank-
shaft turning in the cases either by passing a round
bar through the small ends and supporting on
clean wooden blocks across the crankcase mouth
or by placing a suitable bar into the“deepest
balance hole and allowing the bar to abut against
the crankcase mouth in a similar manner to that
shown in Fig. C22.
Special Note: There is a risk of breaking the oil
shroud portion of the crankcase over the camshaft
if the bar is allowed to abut to this.
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Engine/Primary Transmission C
Fig. C22 Preventing flywheel turning by use of a bar lodged in
a flywheel balance hole
9 With the flywheel still prevented from turning,
remove the nut securing the camshaft sprocket.
Under no circumstances must anything but firm
steady pressure be applied to unscrew the cam-
shaft sprocket nut — normal right hand thread —
unless a dummy cut away timing cover is fitted and
secured with screws at extreme front rear and
bottom. If a hammer or mallet is used without such
a cover to support the end of the intermediate gear
spindle, there is risk of the latter being pulied out
of the crankcase.
The size of the sprocket nut is % in. Whitworth.
Lift the sprocket, idler gear, and timing chain away
as a set. iT the camshaft sprocket should prove to
be tight on the camshaft, it may be removed by
using the special jaws supplied with the 064297
engine sprocket extractor.
Do not remove camshaft key from camshaft
except for replacement.
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Fig. C23 Releasing a tight camshaft using sprocket service tool 064297
11
12
Providing the timing cover joint gasket is not
damaged during dismantling, there is no reason
why it should be removed from the crankcase
facing as it will be perfectly suitable for re-use.
Using Service Tool ET.2003 asshown in Fig. C24,
extract the crankshaft pinion. It should be noted
that the jaws of the service tool locate to the
spaces provided in the pinion backing washer.
Fig. C24 Extracting crankshaft pinion using tool ET 2003
—
ии
-” Engine/Primary Transmission
13
14
15
16
17
18
19
Lift away the pinion key which is of the Woodruff
type. Remove also the backing washer.
Remove the oil sealing disc which is lipped. This
disc tends to cling to the main bearing due to the
presence of oil and the use of two small magnets
or some other means is recommended to lift the
disc clear.
If desired, the timing chain tensioner, clamping
plates, nuts and fan disc washers can be removed
from the crankcase at this stage. |
Dismount the crankcases from the vice so that
they may be parted and the crankshaft assembly
extracted.
Remove the crankcase breather pipe complete
with elbow by slackening the locking nut at the
crankcase or on 850 models by sliding the pipe off
the crankcase breather stub. On 750 models after
engine number 200000 remove the breather and
breather pipe as an assembly, after removing the
locking wire, or flattening the tab washer and
taking out the two securing bolts.
Remove the two studs, one bolt and two set
screws, holding the crankcases together. Unless
the additional bottom stud has been removed to
mount the crankcases in a vice, the stud should be
removed at this stage.
Part the crankcases, releasing the crankcase joint
by the use of bar of wood against the drive side
crankcase as shown in Fig. C25.
Fig. C25 Parting the crankcases using a wood block against the
20
21
22
inner drive side
On Commando engines before engine number
200000, the rotary engine breather disc and spring
should be collected from the drive side cam bush
as the drive side crankcase is lifted away.
Withdraw the camshaft from the timing crankcase
and collect the chamfered thrust washer. Note
that on engines between engine number 200000
and 300000 there is an additional flat thrust
washer that must be collected.
Part the timing side crankcase from the crankshaft.
This practice is preferred to removal of the
crankshaft from the crankcase. Removal is
accomplished without striking the end of the
crankshaft by the use of a tubular drift driven
against the crankshaft shoulder. Fig. C26 illustrates
a suitable tube fitted over the crankshaft, the tube
standing on the bench and a hammer driving a
lump of soft wood against the crankcase facing,
permitting this to be jarred free of the crankshaft.
If removal should prove difficult by this means,
the crankcase in the area surrounding the main
bearing should be heated by a soft flame and the
same removal procedure followed so that the main
bearing and crankshaft together are displaced
from the crankcase. The bearing can then be
removed at a later stage. On engines after number
200000 a roller timing side bearing is used and on
such units there should be no difficulty in
crankshaft removal.
Engine/Primary Transmission C _
Fig. C26 Showing suitable tube to abutt to crankshaft shoulder
yet pass through crankcase
Fig. C27 Supporting the crankcase shoulder on a tube whilst
separating the crankcase from the crankshaft
SECTION C17
CRANKCASE OVERHAUL
The following text covers the renewal of main bearings
only. In our experience the camshaft bushes have an
extremely long life and renewal cannot be accom-
plished without extensive machining facilities. To
remove the main bearings, it is necessary to heat the area
surrounding each main bearing with a soft flame such
as a gasoline or kerosene (petrol or paraffin) blow
lamp or butane or propane. Once the cases have been
heated, in the case of a timing side crankcase equipped
with the ball type of main bearing, use a suitable soft
drift against the inner race of the main bearing and the
bearing can be drifted out. In the case of a timing side
crankcase equipped with the roller type of main bear-
ing, heat the area of the crankcase surrounding the main
bearing and by bumping the joint facing of the cankcase
hard against a flat wooden surface, the main bearing
outer race shouid be dislodged. In the case of drive side
crankcases, the complete crankcase will need to be
appreciably hotter since the only method of removing
the main bearing outer race will be to bump the crank-
case sharply against a flat wooden surface.
To refit the main bearings, the cases must be similarly
heated and the main bearings, whether of the ball or
roller variety should drop, completely freely, into their
housings. The main bearings must be fully home into
the housings both at the drive side and timing side
cases.
SECTION C18
REMOVING CONNECTING RODS
Remove the connecting rods by releasing the two self
locking nuts when it should be possible to pull the
connecting rod away from the cap by hand pressure.
The bearing shells remain in position at this stage but if
they are to be re-used, they must be protected from dirt
and possible damage. It is vitally important that at no
stage are the connecting rod end caps interchanged
between rods and it is equally important that the end
caps should not be reversed on their own connecting
rods.
A scribe marking is used on the connecting rod and end
cap to show the correct direction of fitting. The locating
tabs on both of the bearing shells fit to the same side
of each connecting rod.
SECTION C19
DISMANTLING THE CRANKSHAFT
It is to be expected that the crankshait assembly which
is now to be stripped will contain approximately one
teacup full of oil and provision should be made for
collecting this oil in a suitable receptacle.
Before parting the crank cheeks from the flywheel, it is
recommended that the flywheel be marked e.g. “'T.S.”
for timing side so that it is not reversed during re-
assembly. Proceed as follows:
1 Slacken the fixed nuts on the timing side securing
the crank cheek to the flywheel, noting that the
nuts have been centre punched during assembly
and may be expected to be extremely tight.
2 Jar the crank cheeks free from the flywheel using
a hammer and soft drift. The drive side crankshaft
will come away complete with the two studs, tab
washer and nuts which can now be removed if
desired.
Dependent upon mileage there is likely to be a con-
siderable build up of sludge and foreign matter in both
the crank cheeks and the recess in the flywheel. This
. foreign matter must be cleaned out most thoroughly.
Tool No. 063970 is available to remove roller bearing
races from the crankshaft, as shown in Fig. C28.
SECTION C20
CRANKSHAFT INSPECTION AND
REGRINDING
Wash each crank cheek in clean petrol and blow dry
with an air line. Examine the big end journals for scoring
and remove light score marks by the use of smooth
emery tape. If there is excessive scoring or ovality
and it exceeds 0:0015 in. (-0381 mm) on the big
end journals, regrinding is necessary.
The regrind sizes are shown overleaf. The revised big
end journal sizes necessitate the use of connecting rod
shell bearings of the correct undersize. The steel backed
big end shells are finished to provide the correct
diametrical clearance and must not, under any cir-
cumstances, be scraped. Shell bearings are available
in undersizes of minus 0:010 in., minus 0:020 in.
minus 0-030 in. and minus 0:040 in.
.. Engine/Primary Transmission
Fig. C28 Removing roller bearing inner race using extractor
063970.
SECTION C21
ENGINE LUBRICATION SYSTEM
The Commando lubrication system as shown in Fig. C29
is of the dry sump type, oil contained in the separate oil
tank being fed through a wire strainer by gravity and by
suction through the feed side of the gear type oil pump
to the crankshaft. The oil pump delivers lubricant under
pressure to the oil pressure relief valve and a bleed off
the main feed supplies lubricant to the rocker gear. The
main oil supply is delivered through the end of the
~ crankshaft, (which is sealed by a garter type seal in the
timing cover) to both big ends and escapes between the
big end shells and crank journals to lubricate the
cylinder walls, main bearings, camshaft and cam
followers by splash. Qil collects in the crankcase sump,
the inlet rocker box draining through a drill way in the
cylinder barrel, and the exhaust rocker box draining
through a drill way into the push rod tunnel and
providing additional lubrication whilst returning to the
crankcase between the cam followers to the camshaft.
The return side of the oil pump draws oil from the
sump via the sump filter (or collecting area in later
crankcases) and returns it through the full flow oil filter
to the oil tank. A bleed from the oil tank return pipe at
the tank lubricates the rear chain via a regulator comp-
rising a plastic tube and felt insert.
— a ~~
Engine/Primary Transmission C _..
17405
1 7406 DIA
и |
|
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2
.090 RAD.
u IMPORTANT
1.7305&quot;
I. 73000 A
о
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a
'О9О RAD.
IMPORTANT.
N
1-7205&deg;
1.7200&deg;%
AT AN
i
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-O 90 RAD.
IMPORTANT.
—- ——— a&quot; oY
FIRST RE- GRIND
GRIND, THE CRANKPIN TO
1-7405/1- 7400 DIA. WITH
‚090 FACE RADIUS,
STAMP -.OIO&quot; HERE.
SECOND RE-GRIND
GRIND THE CRANKPIN TO
|-7305/1-7300'DIA. WITH
.O90&quot;FACE RADIUS,
STAMP -.020 HERE.
THIRD RE - GRIND
GRIND THE CRANKPIN TO
1-7205/1- 7200 DIA WITH
.O90 FACE RADIUS.
STAMP -- 030&quot; HERE.
N106
Fig. C29
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Engine lubrication system 850 models
(excepting oil filter and breather,
similar for previous models)
Engine/Primary Transmission C -
SECTION C22
OIL PRESSURE RELIEF VALVE
The relief valve is fitted to prevent oil pressure rising
above 45/55 lbs. sq. inch. It is fitted to the rear of the
timing cover below the rocker oil feed pipe banjo. The
valve consists of a spring loaded steel sleeve pre-set at
the factory using shims to regulate the blow off
pressure and the valve requires no attention. Oil
escaping from the valve returns to the feed side of the
pump. |
SECTION C23
CRANKCASE BREATHER
A timed and ported mechanical crankcase breather is
used prior to 1972. In this design, a rotary disc with
cut-away segment driven by the camshaft and backed
with a light spring mates with a similar stationary disc
fitted behind the left camshaft bush in the crankcase.
An elbow with flexible pipe from the left crankcase leads
to the oil tank. The oil tank breather is connected to
the air filter back plate. 1972 and 1973 750 models have
a non-mechanical breather which is located on the
back of the left crankcase. The 850 engine has a
breather located at the top rear of the timing chest. As
with earlier models, the breather is vented through the
oil tank to the air filter back plate.
SECTION C24
OIL PUMP
The oil pump is of the gear type and is shown in detail
in Fig. C29. The return side of the pump, which is of
twice the capacity of the feed side to provide sufficient
capacity to keep the crankcases clear of surplus oil, is
identified by the wider gears. The oil pump is sealed to
the timing cover bore with a conical rubber oil seal
located on the pump body by a steel ferrule and com-
pressed by the timing cover. Removal of the oil pump
is included in Section C16 and the servicing routine
covered in Section C25.
Fig. C30 Comprising parts of oil pump
SECTION C25
SERVICING THE OIL PUMP
Removal of the oil pumpisdescribedin Section C76. The
criterion of oil pump condition is the degree of end float
on the oil pump pinions, most easily felt by movement
of the oil pump driving gear relative to the pump body.
After some period of use, the tendency is for the
pinions to wear into the pump end covers and such
wear can only be removed by taking off the covers and
flattening down the actual pump body.
1 Detach the pump top covers and drive gear with
drive spindle by tapping the spindles through the
keyed pinion with a pin point drift. The remaining
parts can be lifted from the pump body at this
stage.
2 Wash all the components thoroughly in clean
gasoline (petrol) and allow to dry.
It is most important to correct end float on the feed
gears (the narrow ones) first.
_ Engine/Primary Transmission C
3 Remove the feed gears and rub down the back
plate end of the pump body surface against a high
grade quality emery cloth on a perfectly flat
surfacesuch asasmallsurfaceplate. Flattening ofthe
surface should continue a little at a time until the
stage is reached where, on re-assembly of the oil
pump, there is barely discernible stiffness on the
oil pump driving spindle. This barely discernible
stiffness will indicate that there is just sufficient
freedom of movement and that there is no
excess clearance between the feed gears and
housing. |
4 Remove the feed gears and repeat the flattening
down process on the return side of the pump
body until with the return gears only in the pump
body and the screws tight there is similar slight
stiffness.
5 Strip the pump body again and wash with very
great care. Reassemble the pump and tighten the
screws completely. At this stage there should be
some degree of stiffness in the complete pump.
6 Introduce oil into the feed hole then, holding the
oil pump with one hand, place a ring spanner over
the driving spindle nut, and revolve the oil pump
a number of times to allow oil to circulate com-
pletely. The oil pump should now have freed off
considerably. Slight stiffness remaining should
decrease, if not disappear completely.
SECTION C26
TIMING COVER
There are two garter type seals in the timing cover, one
at the contact breaker housing and one to seal the
crankshaft to the cover.
Contact Breaker Seal — Failure of this seal is indi-
cated by the presence of oil in the contact breaker
housing. To remove the old seal it is necessary to prise
out with a screwdriver or similar implement thus
rendering the seal scrap. A new seal should be fitted,
pressure side, that is spring side, towards the engine and
the seal should be tapped fully home into the housing
using Service Tool 064292.
Crankshaft Seal — This seal is retained in the housing
with a circlip. After removing the circlip, the seal can
be prised out of its housing but will be damaged beyond
further use. Care must be taken to avoid damage to the
‘housing. Fit the new seal pressure side towards the
timing cover and drive fully home using Service Tool
064292. Refit the circlip “sharp” side towards the
crankcase and make sure that it is fully seated all-
round. |
Fig. C3t Showing blanking plug in position in timing cover
Fig. C32 Positions and lengths of odd timing cover screws
Where a new timing cover is being prepared for fitting,
check that the blanking plug shown in Fig. C31 is in
position. The timing cover odd screw lengths are
shown in Fig. C32.
Engine/Primary Transmission C
SECTION C27
RE-ASSEMBLY OF THE CRANKSHAFT
Prior to assembly, it is vital to polish the crank journals
using a fine grade emery tape then make absolutely
sure that all parts are washed very thoroughly in
gasoline (petrol) until clean.- Ensure also that the oil
ways are clean and blown through with an air line.
Re-assembly proceeds as below:
1 Fit the drive side crank cheek to the flywheel, mat-
ing the markings previously made.
2 Fit the two inner studs through from drive side to
timing side. Position the locking tab over both of
the studs from the drive side and fit nuts.
3 Assemble the timing side crank cheek over the
studs and the dowel in the flywheel.
4 Assemble the four remaining studs, driving side to
timing side, noting that the studs are a good fit
into the crank cheeks and will in all probability
need to be tapped home with a drift.
5 Fit the second tab washer over the inner studs,
followed by the timing side nuts.
6 Tighten the remaining nuts, commencing with the
two washers and then proceeding diagonally,
tighten the others.
7 Tap over the tab washers or use vice grips to bend
the tabs over.
8 Ensure that the oil way blanking plug is fitted in
the timing side crank cheek, particularly if a new
timing side crank cheek is in use.
LONG
STUDS
SHORT
STUDS
TAB WASHER
Fig. C33 Showing crankcheek to flywheel securing hardware
SECTION C28
RE-ASSEMBLING CONNECTING RODS
TO CRANKSHAFT
As a matter of practice always use new bearing shells
and at the time of fitting the shells, smear them with
clean engine oil. Proceed as follows:
1 Press the drilled shell into the connecting rod big
end eye and rotate into position, locating with the
tab.
2 Fit the plain shell into the connecting rod cap and
again locate the tab. The tab positions are shown
in Fig. C33.
3 Fit the connecting rods but before doing so, note
that it is unnecessary to renew the connecting rod
bolts though new nuts should always be used.
The connecting rods must be fitted with the oil
holes from the big end eye outwards in each case.
Fit the end caps with shells, ensuring that the
mating marks align, and tighten the nuts evenly
by hand.
4 Tighten the connecting rod nuts to a torque read-
ing of 25 Ibs./ft. (3-456 Kg/m). +
Fig. C34 Connecting rods showing both sides of big end eye
and bearing shell tab locations
a
_ Engine/Primary Transmission C
—
SECTION C29
RE-ASSEMBLING CRANKSHAFT
TO CRANKCASES
Since it is simpler to slide the drive side crankcase with
the outer main bearing race over the complete assembly
of the other crankcase with crankshaft than vice versa,
we recommend the following routine:
1 Push the timing side crankcase over the crankshaf.
which must be supported upright on the bencht
See Fig. C35. At this time check that the connecting
rods clear the crankcase mouth of the crankshaft
end of the bearing. If the bearing is too tight to
push home over the crank, place a scrap main
bearing inner race and a large washer over the
crankshaft, outboard of the timing side crankcase
then, using the oil pump driving worm on the
crankshaft, pull it home through the bearing.
2 Position the camshaft thrust washer over the
timing side camshaft bush and locate this, flat
side towards the crankcase and bush, locating
with a blob of grease. On engines between
numbers 200000 and 300000, a flat thrust washer
is fitted between this chamfered washer and the
crankcase. Ensure that this flat washer is properly
located with its tab in the hole provided below the
bush.
[]
—— 4
+
Ц
N32
Fig. C35 Pushing timing side crankcase over crankshaft
с
Smear the timing side crankcase joint facing with a
non-setting sealing compound. A little may be
applied to the timing side case facing where there
IS NO spigot.
Into the drive side camshaft bush fit the rotary disc
followed by the spring on engines before
200000 and camshaft, oiling the bearing surface
slightiy.
Engage the camshaft with the driving dogs on the
disc on engines before 200000.
Offer the drive side crankcase to the timing side
after oiling the camshaft bearing area and the drive
side roller main bearing. The operation of mating
the crankcases is shown in Fig. C35. It will be noted
that the camshaft is held in position against the
breather disc and spring with one finger during
this operation before 200000. Ensure that washer
tabs are seated throughout this operation until
cases are mated. It is most important that the drive
side connecting rod does not come into contact
with the crankcase mouth and at the final stage of
mating the crankcases, it may well be necessary to
turn the tachometer drive to locate into the cam-
shaft worm drive.
Now tap the crankcases together with a% ide
hammer until the joint faces meet all-round. =~
3
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uno
Fig. C36 Mating crankcases. Note the camshaft is held against
the spring and disc with the finger
Engine/Primary Transmission C _
8
10
11
12
Before tightening the crankcase securing nuts,
ensure that there is end float on the camshaft,
indicating its freedom.
Fit the crankcase front and rear screws, studs, nuts
and washers.
Fit the short front crankcase mating bolt from drive
side to timing side then fit the front bottom stud
unless the crankcase is to be mounted in the vice
in which case this front bottom stud should be
omitted until a later stage.
Fit the two slot headed set screws from the timing
Tighten the mating nuts and screws evenly in
rotation and wipe away surplus jointing compound
remaining on the outside of the crankcase joint
facing.
SECTION C30
ASSEMBLING RIGHT (TIMING SIDE)
OF ENGINE
Having assembled the crankcases as detailed in Section
C29, mount the crankcases in a plain jaw vice to
facilitate handling. Re-assembly of the cam chain,
sprockets and oil pump may now be undertaken as
follows :
1 Fit the oil sealing disc over the timing side crank-
shaft, lip outwards.
2 Fit the cut-away backing washer.
3 Fit the woodruff key into the crankshaft then
place on the crankshaft pinion, chamfered teeth
and timing mark outwards. It may be necessary to
tap the pinion fully home using a suitable tube as
a drift.
4 Turn the crankshaft to top dead centre so that the
timing pinion marking is uppermost.
5 Take the intermediate gear sprocket, the camshaft
sprocket and cam chain, assembling as shown in
Fig. C37. For correct timing the timing marks must
be 10 rollers apart on the chain as shown in the
illustration.
Fig. C37 Assembly of timing chain and sprockets. Note arrows
6 Locate the camshaft sprocket and intermediate
gear and sprocket in position, mating up the
marked space between the teeth on the inter-
mediate gear with the marked tooth on the timing
pinion. On all engines it will be found that there is
a paint marking to illustrate more clearly the timing
position on the intermediate timing gear.
Assemble the chain tensioner as shown in Fig. C38,
noting that the clamping plates differ, the inner
one being thinner than the outer and the inner
being fitted long end down whilst the outer clamp-
ing plate is fitted long end up.
Fit the chain tensioner, fan disc washers and nuts
moving the tensioner blade up to give a maximum
fin. (48 mm) up and down movement at the
tightest point of the chain and nip up the tensioner
securing nut. Before finally locking up these nuts,
rotate the crankshaft a little at a time, checking at
each stage the chain tension lest there should be
a tight spot on some point of the chain. When
chain tension is correct, finally lock up the ten—
sioner securing nuts.
_ Engine/Primary Transmission C
Fig. C38 Chain tensioner showing thin inner plate long end
downwards
9 Fit the oil pump driving worm which is left hand
threaded.
10 Fit the camshaft sprocket nut which is normal
right hand threaded.
11 In order to tighten both the oil pump driving worm
nut and camshaft sprocket nut securely it is
necessary to sprag the crankshaft with a suitable
bar placed in the deepest of the flywheel balance
holes as shown earlier in Fig. C22.
Under no circumstances tighten the camshaft
sprocket nut by shocking using a box spanner,
tommy bar and hammer since an even pressure is
required specifically for tightening this nut.
Tighten securely the timing pinion nut.
Prior to fitting the oil pump it is desirable, if the pump
has been stripped or parts renewed, to prime this. The
pump should be turned by hand and oil fed into the gears
by the use of an oil gun. Very late engines use a joint
gasket between the oil pump and crankcase joint faces
and where a joint washer is used at this point, under no
circumstances should the conical rubber seal between
the oil pump and timing cover be equipped with packing
shims. Proceed as follows:
12 Fit the oil pump and secure with two nuts without
washers. A torque figure of 10/12 ft. Ibs. (1-383
to 1-659 Kg/m) is required.
13 Fit a new conical rubber oil seal part number
NMT272 on the oil pump outlet stub and dispense
with any shims which may have been fitted
between the seal and pump body at the time of
dismantling. Over compression of the seal will
render it unfit for further use.
14 After the oil pump is secured, recheck the security
of the driving gear nut.
? Y
+
SECTION C31
REFITTING THE TIMING COVER 7
The timing cover should be prepared by washing very
thoroughly in clean gasoline (petrol) and if necessary
by renewing the oil seals as described in Section C26.
If a new timing cover is to be fitted, check that the
blanking plug is fitted into the boss for the pressure
relief valve. These features are shown in Fig. C317.
1 Fit the contact breaker oil seal protection tool
061359 into the camshaft and tighten. This will
allow the contact breaker seal to pass over the
camshaft without damage as the timing cover is
placed in position. Lightly oil the tapered surface
of this tool.
2 Pass the contact breaker lead through the hole in
the timing case, then locate the cover in position.
3 Fit the timing cover screws. The odd screw
lengths are shown in Fig. C32 but the remaining
screws are all of the same length. Secure the sat
of screws.
4 Remove the contact breaker seal tool 061359.
5 Prepare the auto advance mechanism by cleaning
very thoroughly and lubricating sparingly with
clean engine oil. Ensure that the taper for the auto
advance cam is clean and dry then offer the auto
advance unit loosely into position.
6 Fit the contact breaker plate, yellow lead rear-
wards and secure with the pillar studs central in
the adjustment slots. For ease of handling at a
later stage, centralise both contact breaker plate
adjusters. These are indicated in Fig. C50.
— Engine/Primary Transmission C _
SECTION C32
RE-ASSEMBLY OF CRANKCASE
ASSEMBLY TO FRAME
Re-assembly of the crankcase into the frame is virtually
a reversal of the dismantling procedure though the
operation of fitting the front mounting is given com-
plete as below:
1 With the crankcase attached to the rear engine
mounting plates, lift the crankcase assembly and
gearbox, pivoting on the rear mounting to insert
the bottom studs from right to left. The direction
of fitting this stud is important only on 197
models. |
It is necessary to fit the front mounting at this stage
before final tightening of all the engine plate to crank-
case bolts and before fitting the inner chaincase.
Attention to the front mounting and shimming has
already been carried out on the bench asin Section F15.
Fig. C39 Lifting front mounting into position using bottom bolt
as pivot
2 Take the front mounting and slide the bottom
mounting to crankcase stud into position.
nea ow ak
-
3 Using the bottom stud as the pivot, lift the mount-
ing into position on the crankcase bosses as in
Fig. C39.
Fig. C40
Inserting front left gaiter mounting cap group
4 Grease the mounting cap and shims and assemble
each group of plastic washers, spacers and
gaiters ready for insertion in sets between the front
mounting tube and frame.
D Insert the right set first, then place the washer for
the mounting front bolt against the frame, aligning
the mounting centre bolt head with the timing
case and inserting the centre bolt through to the
left hand side just short of the isolastic bush. Note
that it may be necessary to lift the crankcases a
little to ease fitting of this bolt.
6 Asin Fig. C40 insert the left set of gaiter, mounting
cap, shims, etc., and again, by lifting the crankcase
for improved hole alignment, slide the centre bolt
fully home.
7 Use a small screwdriver with care to feed the lip
of the gaiter over the shim cap at both ends of the
mounting, revolving the gaiter a little to facilitate
this operation.
&quot;E
2 Engine/Primary Transmission C )
8 Fit and secure the centre bolt nut and washer and
tighten to 25 Ibs./ft. (3-456 Kg/m).
9 Fit the top bolt to the assembly.
The remaining items of the engine plates which have
been assembled as a reversal of the dismantling
. procedure should now be tightened to the recom-
mended torque settings. The i in. diameter engine to
frame stud nuts require a torque figure of 25 to 30
Ibs./ft. (3-456 to 4:148 Kg/m) and the +; in. nuts to
15 Ibs./ft. (2-074 Kg/m). ` #6
Fig. C41
Priming crankshaft with oil
Prior to fitting the bottom connection for the rocker
feed pipe it is most desirable to prime the crankshaft
with approximately a teacup full of oil. This is most
easily achieved by the use of an oil syringe, short length
of flexible pipe, and a spare rocker feed pipe banjo
which can be connected at the rear of the timing case
The priming operation is shown in Fig. C41 .
SECTION C33
REFITTING PISTONS AND CYLINDER
Throughout the fitting of the pistons and cylinder,
take care to protect the connecting rods and pistons
from damage caused by these parts coming into contact
with the crankcase mouth or cylinder base studs.
Proceed as follows:
1 Grease the crankcase studs lightly and apply a coat
of Loctite “plastic gasket” material to cylinder base
flange.
2 Fit one circlip to each piston, sharp edge out-
wards.
3 Heat the pistons in hot water to ease entry of the
wrist pins (gudgeon pins).
4 Take special note that 750 pistons are handed and
marked “LH” and “RH” respectively and “EX” at
forward side. -
If the marks are illegible the pistons may be recog-
nised by the fact that the inlet valve cutaway is
away from the edge of the crown in each case.
*5 Oil the small end eye and wrist pin bosses and
push each wrist pin home by hand.
6 As each piston is fitted, fit the second circlip sharp
end outwards.
7 Turn the engine crankshaft backwards to lower the
pistons, then support the pistons as in Fig. C41 on
two suitable bars which must not overlap the
timing case.
8 Position the piston rings with the top compression
ring gap central at the front of the piston body and
the second taper ring gap central at the rear of
the piston body.
9 Position the scraper ring expander to the side of
the piston body with the rail gap 1 in. to the left
and right of the expander gap to prevent the rail
ends spragging in the connecting rod clearance
cutaways in the cylinders.
10 Smear both piston bodies with clean engine oil.
Fit piston ring clamps (also shown in Fig. C41)
to keep the piston rings closed. Do not over-
tighten the ring clamps which would tend to
prevent the ring clamps sliding as the cylinder is
offered. |
Engine/Primary Transmission C
A 7 Pi
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— IT &copy; A
| In — ;
EC | &copy; _ й ( A | er
7
Fig. C42 Fitting cylinder over pistons. Note piston supporting
bars and ring clamps in use
11 Offer the cylinder over the pistons as shown in
12
13
14
Fig. C42, pushing the cylinder down to slide the
ring clamps down quickly. The pistons are now
entered in the cylinder bores.
Remove the support bars and both rings clamps.
Partially lower the cylinder but start cylinder base
nuts before lowering the barrel completely. Only
the large centre nut lacks a washer.
Tighten the cylinder base nuts in sequence.
Tighten the $ in. nuts to a torque setting of 25 Ibs.
/ft. (3-456 Kg/m) and + in. nuts to 20 Ibs./ft.
(2765 Kg/m). See Fig. C43 for 850 torque
settings.
S 240 in 16/20 ft Ib (2:75 Kg/m)
360 in 1b/30 fe 1b (4-15 Kg/m)
@ 300 in 16/25 fe 1b (3,75 Kg/m)
Fig. C43 850 cylinder base securing torque.
SECTION C34
ASSEMBLING PRIMARY TRANSMISSION
The primary transmission is assembled in the order:
inner primary chaincase, engine sprocket, clutch and
primary chain, rotor and stator and finally the outer
primary chaincase. The full routine is detailed below :
1 Check that the engine sprocket key will pass freely
through the keyway in the sprocket and if neces-
sary relieve any roughness.
2 Fit the engine sprocket key into the crankshaft.
3 Fittheinnerchaincase to crankcase gasket, holding
in position with grease or a non-setting jointing
compound.
4 Check that the plain washer is on the chaincase
support stud (on some units an additional thinner
large diameter washer is used at this point).
5 Ensure that the inner and outer joint faces of the
inner chaincase are clean.
6 Fit the inner chaincase, ensuring that the gearbox
mainshaft seal passes over the mainshaft without
damage and that the chaincase forward end is
fully home.
- Engine/Primary Transmission C
——
vio EA
SL
Fig. C44 Using grip wrench to squeeze over tab washers at
inner chaincase
Fit the inner chaincase securing tab washers and
set screws and squeeze over the locking tabs
using a grip wrench as shown in Fig. C44.
Assemble the clutch location spacer, recessed
portion towards the gearbox, followed by the
spacing washer. The purpose of the spacing
washers is to align accurately the clutch sprocket
with the engine sprocket.
Assemble the engine sprocket and clutch sprocket
to the triple row chain ready for fitting.
Fig. C45 Winding diaphragm spring circlip into position
10
11
12
13
14
16
16
17
Offer the engine sprocket, clutch sprocket and
primary chain as a set, feeding the stator through
between the chain runs. The stator is still attached
to the inner chaincase by the lead passing through
the chaincase grommet.
At this stage push the engine sprocket fully home
over the woodruff key, if necessary using a tubular
drift to push the sprocket fully home. At the same
time the clutch will need to be pushed home firmly
over the splines of the mainshaft.
Fit the clutch centre securing nut and single spring
washer (early) or nut and tab washer (late
models) in the case of the tab washer engaging
the ends, in the 2 holes in the clutch centre.
Loosely position the rear brake pedal and footrest,
apply the rear brake fully and tighten the clutch
centre nut. The correct torque for the clutch
centre nut is 70 lbs./ft. (9-678 Kg/m). Squeeze
the centre portion of the tab washer to 2 flats on
the nut (late models). Proceed to assemble the
clutch.
If for any reason the clutch plates have been
removed from the housing, re-assemble these, an
inner splined friction plate first into the housing,
followed by a plain steel alternately, finishing with
the robust iron pressure plate.
The clutch diaphragm spring should be assembled
to the spring tool and tensioned as shown earlier
in Fig. C13 until the diaphragm spring is flat.
Offer the diaphragm spring on the tool to the clutch
housing and push home as far as possible.
Enter one end of the clutch spring circlip and con-
tinue to wind the remainder of the spring into the
housing as shown in Fig. C45.
&gt;
-
Engine/Primary Transmission C
Fig. C46 Clutch operating lever in correct position
18 When the spring circlip is well bedded into the
housing all-round, remove the spring tool by
slackening the centre bolt.
19 Fit the clutch push rod adjuster screw and lock
nut.
20 Adjust the clutch push rod with the handlebar
adjustment slackened off completely. Screw in the
adjuster until there is just perceptible lift on the
diaphragm spring and slacken back one full turn,
holding in this position whilst the lock nut is
tightened completely.
&raquo;
It is possible for the clutch operating lever in the
kickstart case to have dropped down between the
thrust ball and roller against which the lever lifts
and if this has eccurred, it will be found that the
clutch is inoperative, and it will be necessary to
remove the inspection cover which is secured by
two screws to the gearbox outer cover, slacken
batk fully the push rod adjuster and lift the lever
back into position before adjusting. In Figs. C46
and C47 we show the lever in its correct position
and the lever as it may be found if it has dropped
21 Assemble the shims on the crankshaft over the
engine sprocket, followed by the spacing collar
with the recess outwards. |
22 Fit the rotor key, the inner end of which passes
into the recess in the collar.
23 Ensure that the rotor is free of any magnetic
particles Xt may have attracted whilst dismantled
and fit the rotor to the shaft and key, name and
у timing marks outboards.
24
25
26
27
Assemble the rotor nut and fan disc washer and
with top gear engaged and the rear brake applied
fully, tighten the rotor nut fully to 70 to 80
Ibs./ft. (9-678 to 11-060 Kg/m).
Fit the three stator spacers on to the stator mount-
ing studs followed by the stator on which the lead
must be outboard at the 5 o-clock position.
Assemble the plain washers and stator securing
nuts and tighten to a torque setting of 15 Ibs./ft.
(2:074 Kg/m). Check the gap between the stator
and rotor which must give a minimum air gap of
0-008 in. to 0-010 in. (0-2032 to 0:254 mm).
Any misalignment of the stator mounting studs
would account for reduced air gap at any one
given point and can only be corrected by very
careful slight re-alignment of the studs.
Check that the chaincase sealing band is snugly
in position in the recess in the outer face of the
inner chaincase with the join in the band at the
top then place the outer chaincase in position.
Fig. C47 Clutch operating lever in wrong position where lever
has dropped down
28 Secure the outer chaincase using the single centre
sleeve nut and washer.
29 In order that the point is not overlooked it is
recommended that lubricant is added to the
chaincase at this stage.
30 Refit the left hand foot-rest and brake pedal
. - assembly, securing with three nuts, two washers
and the stop lamp lead support bracket acting as
the third washer on the bottom stud.
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—
- Engine/Primary Transmission C
SECTION C35
CLUTCH OPERATING MECHANISM
The clutch is connected from the left handlebar control
to the clutch operating lever within the gearbox cover.
As the lever is withdrawn, the clutch operating lever is
lifted, exerting pressure on a ball bearing against the end
of the clutch push rod. The push rod forces outwards
the centre of the diaphragm spring, relieving the pres-
sure and allowing the clutch plates to separate. For the
clutch to operate correctly, the degree of free movement
on the cable and clutch push rod must be controlled.
Excessive slack may prevent the clutch freeing com-
pletely and excessively tight adjustment will result in
the clutch plates being held apart. Adjustment is pro-
vided on the cable and push rod.
Clutch Adjustment
1 Slacken cable adjustment at the handlebar control
as far as possible.
2 Remove the clutch adjuster inspection cap from
the chaincase.
3 Remove the inspection cap from the gearbox end
cover.
4 With the index finger, move the clutch operating
lever to and fro inside the gearbox cover to estab-
lish whether or not there is slight movement. If
there is, clutch push rod adjustment is correct. If
there is not, rectify as follows.
5 Release nut (B) in Fig. C48 then turn the screw (C)
gently anti-clockwise until movement is felt on the
right side operating lever.
6 Turn screw (C) in a clockwise direction until it is
felt that the screw just touches the push rod.
7 Unscrew adjustment screw (C) one full turn and,
holding in this position retighten locknut (B). This
ensures the correct free movement on the clutch
push rod.
8 Adjust the clutch cable at the control to provide
+ in. to Tin. (4:76 to 6-35 mm) free movement
between the cable outer casing and adjuster.
CLUTCH PLATES
The clutch dismantling procedure is covered as part of
Section C13 &quot;Dismantling Primary Transmission and
Clutch.” However, it is sometimes considered necessary
to remove the plates separately for inspection.
To gain access to the clutch plates, follow Section
C13 &amp; C14 items 1109. Next remove the clutch pressure
plate followed alternately by the internal splined
friction plates and external splined plain steel plates.
After removal, wash all the clutch plates and the
pressure plate in gasoline (petrol) until perfectly clean,
then allow to dry.
Reassembly is a reversal of the foregoing but full
instructions are given in Section C33.
7
Fig. C48 Clutch adjustment
Plate Inspection
Examine the friction plates for obvious wear to the
splines and for “charring” of the surface such as would
occur during prolonged clutch slip. Examine the plain
steel driven plates for deep scoring or grooving. Check
the external splines for obvious wear, and check each
plate in turn on a surface plate for flatness. Any badly
worn or distorted plates must be renewed before
reassembly.
EN
|
SECTION C36
TACHOMETER DRIVE
The tachometer drive is taken from the worm drive at
e right end of the camshaft. The cable has an adaptor .
for the cable between the lower end of the cable and
tachometer driven gear. The driven gear is removable
after removing two screws and lifting clear the housing
and ‘O’ sealing ring but damage to the drive gear can
‘only be corrected’by replacing the camshaft.
~ SECTION C37
REMOVING AND REFITTING ENGINE
COMPLETE
For ease of handling the engine unit may be removed
from the mounting plates as a unit so that it can be
dealt with on the bench. Proceed as follows:
1 Remove the left footrest and brake pedal and
allow these to hang on the cable.
2 Drain and remove the outer primary chaincase,
alternator rotor nut and alternator stator. The
stator can be left attached to the inner chaincase
by the lead but disconnect the two connectors
beneath the airbox and lever off the rotor.
3 Slacken off clutch adjustment, compress the clutch
diaphragm spring (this requires tool 060999) and
remove circlip.
4 Fit clutch hub too! 061015 and remove clutch
centre nut and fit engine sprocket extractor tool
064297. Remove engine sprocket and lift entire
engine sprocket — primary chain — clutch assembly
— away.
5 Flatten tab washers” *locking three bolts around
crankshaft stub, remove the three bolts and lift off
inner chaincase.
6 Remove rubber breather hose (near primary cover
on early models ; under rear of engine on 1972 and
later; at rear of timing chest on 850).
7 Detach engine ground wire attached to lower left
crankcase stud.
8 Remove fuel tank, ignition coils, carburettor top
caps and withdraw slide assemblies: Remove
exhaust pipes and upper Isolastic head steady.
=
a
-
9 Drain oil from oil tank and remove oil fot lines
from boss beneath timing cover. Remove rocker oil
feed pipe.
10 Disconnect the contact breaker lead wires and
tachometer drive cable.
11 Slip a sturdy support (wood block or metal rod)
between engine and lower frame tubes.
12 Remove bolts holding rear of engine to engine
cradle so engine hinges on front Isolastic mount.
13 Loosen small bolts holding front engine mount.
STEADY ENGINE and remove large lsolastic
mount bolt, then the small bolts and lift out front
Isolastic mount.
14 Engine is now free and can be lifted clear of frame
to right side on to work bench.
Refifting is a direct reversal of the foregoing.
SECTION C38
IGNITION TIMING
Ignition timing can be checked and if necessary reset
either with the engine stationary or, using a strobo-
scope, with the engine running. The stationary method
is quite satisfactory where a stroboscope is not avail-
able. However, for greater accuracy, the stroboscope
method is preferable, since it also checks auto
advance function. A timing indicator plate is
attached to the outer primary chaincase to align with
the corresponding mark on the rotor, the marks being
visible after removal of the chaincase inspection cap
(see Fig. C49). The latest Lucas rotor has two timing
markings opposite each other. Note that the presence
of the surplus marking will not affect timing, either
static or with a stroboscope.
To explain — the engine must be running for a strobo-
scope to be used. Setting the timing by the wrong
marking would mean the spark was timed at bottom
dead centre and the engine would not fun. If the engine
is timed on the correct stroke, the stroboscope will not
pick up the wrong marking. Similarly with static timing,
only the correct marking will align with the calibrated
scale in the primary case with the piston near top dead.
centre on the firing stroke for the cylinder being timed.
Engine/Primary Transmission C _
i
&gt;
,
%
*
TIMING MARK
ON ROTOR
Timing plate visible after removal of inspection cap
from chaincase
Fig. C49
Ignition Timing Basic Procedure Prior to
Checking j
Straightforward assembly of the auto-advance mechan-
ism and contact breaker assembly is covered in Section
C31 as part of the Timing Cover reassembly procedure.
It is however, necessary to locate the auto-advance
cam approximately prior to timing, It is assumed that
the auto-advance mechanism is lose assembled to
the taper in the camshaft and that the contact breaker
backplate screws are central in the adjustment slots.
Remove the inlet rocker cover and the right hand
exhaust rocker cover and both sparking plugs then
turn the engine forwards on the kickstart until T.D.C.
is located on the right cylinder with both valves
closed at the firing position. Identify by wire colouring
the contact breaker points for the right cylinder then
turn the auto-advance cam until it just starts to open
this set of points. Secure the cam with washer and
centre bolt. The engine is now ready for accurate
timing.
Engine/Primary Transmission C
Te
Fae
Ce У,
Ignition Timing Procedure — Engine Static &gt;” той
1 Remove both spark plugs.
7
2 Remove the inspection cap on the chaincase.
+
3 Remove the contact breaker cover.
4 Clean and adjust the contact breaker points as
described in Section C40. | |
Note that if, at any later time, contact breaker
adjustment is disturbed or allowed to vary,
ignition timing will be altered. This necessitates
retiming of the engine.
5 Remove the auto advance cam centre bolt.
6 Replace the washer from this bolt with the special
: washer 06-0949 having a hole large enough to
_ clear the central portion of the unit and thus abut
to the cam.
&gt;
7 Replace the auto advance cam bolt with special
rotate the auto advance to the full
washer,
advance position (it will rotate only one way),
hold and tighten the bolt. The washer bearing
against the cam will hold this in the full advance
position. |
8 Establish that the cylinder on which the timing is
being checked has both valves closed at Top Dead
Centre (T.D.C.) and rotate the engine forwards by
engaging top gear and turning the rear wheel,
until this is the case.
The contact breaker points leads are black and yeliow
or black and white and this feature allows the operator
to check which set of points ars feeding which coil and
cylinder. The factory standard arrangement is for the
left coil ant+cylinder to be fed by the yellow/black rear
set of points.
9 Rotate the engine backwards gently until the
machined mark on the rotor registers with 28&deg; on
the indicator plate. At this precise moment the
contact breaker points should start to open in
which case timing is correct.
Engine/Primary Transmission C _
The -exact point of separation can be determined by
inserting a strip of very thin paper between the points.
The points will grip the paper when closed. By moving
the engine s/owly, a light pull on the paper will dislodge
this at the exact point of separation. Take care not to
leave a shred of paper between the points when using this
method. A preferable method is to use a low wattage
bulb and holder with a short length of wire attached to
the bulb body with a second length of wire attached to
the bulb connection. Crocodile clips should be
attached to the loose end of both wires. Connect one
wire to the contact breaker spring of the set of points
being checked and the gecond wire to a suitable earth
point on the engine. буи оп the ignition and as the
engine is turned, the bulb will light at the exact point of
separation.
10 If the timing is incorrect, i.e. the points do not open
at 28” before T.D.C., release the two screws in
elongated holes which secure the main backplate
and rotate it in the housing. To advance the timing,
move the baseplate clockwise and to retard, move
the baseplate anti-clockwise. When the timing is
correct, secure the backplate screws.
11 Using the same technique, check that the contact
breaker points open at 28&deg; B.T.D.C. on the firing
stroke for the second cylinder. If incorrect, make
adjustment by movement of the secondary back-
plate. To do so, slacken screws (A) in Fig. C50 and
use the eccentric headed adjusting screws (B) to
move the mounting plate. When timing is correct,
re-secure the screws (A).
Ignition Timing Procedure — Engine Running
(Stroboscope Method)
This method is greatly preferred for extreme accuracy
in setting. Prior to checking timing, clean and set both
sets of contact breaker points to the figure given in
“General Data.” |
Note that late models have two marks on the rotor but
that if the ignition timing is sufficiently correct for the
engine to run at all, the stroboscope will only detect the
correct marking. If the engine has been rebuilt and
ignition timing is being set from scratch, firstly follow
the basic procedure in the preceding text. Commence
stroboscopic timing as follows:
&gt; Remove the inspection cap on the chaincase to
reveal the degree indicator plate and timing mark
on the rotor.
Connect the stroboscope to the H.T. lead on the
right cylinder and use a battery separate to that on
the motorcycle to power the lamp, thus eliminating
possible incorrect readings. For the full method of
connection follow the stroboscope lamp manu-
facturer's instructions.
Identify by lead colours the set of contact breaker
points on which timing is being set by the colour
of the wiring at the points and the ignition coil.
Start the engine and run at a steady 3000 r.p.m.
indicated on the tachometer.
Shine the stroboscope lamp on the indicator plate.
If timing is correct, the rotor marking will register
with the 28&deg; marking on the indicator plate. If the
marks do not align, the timing must be adjusted.
To adjust the timing at the first set of points,
release the two screws in elongated holes which
secure the backplate and rotate it in the housing.
To advance the timing, move the baseplate clock-
wise and to retard, move the baseplate anti-
clockwise. Move the backplate on its slots until
the rotor mark and 28&deg; marks align when checked
with the stroboscope then secure the backplate
screws.
Reconnect the stroboscope for the left cylinder
and again check for rotor mark alignment at 28&deg;.
If timing is incorrect for the left cylinder, correct by
slackening off the clamping screw for the
secondary backplate for this set of points then use
the eccentric headed adjusting screw to move the
secondary backplate (see Fig. C50-secondary
backplate screws are marked “A” and eccentric
screws are marked “B&quot;’). Recheck timing with the
stroboscope and when correct, secure the screws
A.
_Engine/Primary Transmission С
SECTION C39
AUTO ADVANCE UNIT
The auto advance unit fitted behind the contact breaker
plate in the timing cover automatically and progressively
advances the ignition timing as the engine speed
increases, and returns it to the fully retarded or static
position when the engine stops.
To expose the mechanism, it is necessary to remove the
contact breaker plate complete, but before doing so
mark the exact position of the plate so that when it is
refitted the timing is not disturbed.
Remove the contact breaker plate fixing screws and
take off the plate complete with the contact sets.
Ensure that the springs of the auto advance unit are
intact with the taper loops attached to the pins. Check
the automatic action by turning the cam by hand to the
fully advanced position in which the bob weights will
be fully extended. When the cam is released, the
springs should return the bob weights to the static
position.
Lubricate the mechanism sparingly. Do not over lubri-
cate as an excess of oil may reach the contact breaker
points. If the contact breaker plate has been removed
from its original position without being marked, the
ignition timing should be checked and reset as in
Section C38 when the plate has been refitted.
~~ Fig. C50 Lucas contact breaker
SECTION C40
CONTACT BREAKER ASSEMBLY
Commandos have been fitted with two different Lucas
contact breaker assembly systems. These systems are
similar, but each requires a different contact point set
and has its own peculiar adjustment procedure.
The Lucas 6 CA contact breaker was fitted to Com-
mandos produced prior to 1973. All 1973 750's and all
850's have the Lucas 10 CA contact breaker assembly.
Both systems have a separate and independently
adjustable contact set for each cylinder, see Fig. C50.
Each contact set is mounted on its own crescent-shaped
assembly plate that is fixed to the circular base plate by
two screws (A). When these screws are loosened, the
assembly plate can be moved in relation to the ignition
cam (and the base plate) by the eccentric screw (B).
This permits a very accurate setting of ignition timing
for each cylinder.
The difference in the two systems is in the fixing of the
contact points set. The earlier 6 CA used only one
fixing screw and an eccentric adjusting screw (C). The
10 CA uses two fixing screws to secure the contact set
to the assembly plate. This system requires that the
plate be moved by a screwdriver blade or similar tool
to secure adjustment.
The circular base plate is secured by two screws (the
tapped screws securing the outer cover). To
advance the timing on both cylinders an equal amount,
move the baseplate clockwise. To retard, move the
baseplate anticlockwise.
Adjusting Contact Breaker Points Gap
Remove the spark plugs so that the engine can be
rotated easily. A small mark located near the lubrication
slot on the cam marks the highest lift position on the
ignition cam. Rotate the engine until this mark aligns
exactly with the nylon heel of the contact breaker: at
this position the points will be fully open. Check the
gap with a 0-015 in. (-38 mm) feeler gauge. If adjust-
ment is necessary, slacken the contact breaker fixing
screw(s), according to type of system fitted. Move the
contact set by the method applicable to your assembly
until the correct gap is obtained. Tighten the securing
screws. Recheck the gap to ensure that the adjustment
was not disturbed by the fixing screws. Adjust the other
contact set in a similar manner.
Engine/Primary Transmission _
Maintenance of the Contact Breaker
Every 5,000 miles (8,000 kilometres) the contact
breaker points should be examined to determine their
condition. Remove the nut securing the contact breaker
spring to the anchor post and lift off the spring heel,
together with the terminals, insulating bush and the
insulating washer. Remove the fixed contact plate
locking screw and take off the fixed contact plate.
Points which are slightly burnt or pitted can be smoothed
with a fine carborundum stone and afterwards cleaned
with a brush moistened in petrol or white spirit; if they
are badly affected they should be renewed.
Before reassembly, smear the contact breaker pivot post
and the cam very sparingly with Retinax “A” grease and
add three drops of engine oil to each lubricating felt.
When reassembling ensure that the insulating washer,
contact breaker spring, terminal and insulating bush are
fitted in the order shown in Fig. C47 and that the
terminal tags are inside the curve of the spring. Finally
retime the ignition as described in Section C38.
SECTION C41
CHAINS
It is important to maintain the correct chain tension
since if the chain is too tight the engine and gearbox
bearings will be pre-loaded in the case of the primary
chain and the gearbox and rear wheel bearings will be
pre-loaded in the case of the rear chain. Pre-loading
will inevitably cause premature bearing failure. Con-
versely, if the chains are too slack then premature wear is
inevitable on the sprocket teeth.
The primary chain operates in an oil bath formed by the
primary chaincase and requires no lubrication from an
outside source providing the chaincase level is main-
tained. The rear chain is lubricated automatically from
the oil tank via a restrictor located to the rear of the tank.
However, the rear chain is not fully enclosed and from
time to time requires cleaning and lubricating manually.
Chain Serviceability
Both in the case of single row (rear) chain and triple
row (primary) chain, chain length extention of 2% is
permissible before the chain is considered to have
reached the end of its usefulness. This figure presumes
that extension is checked only when the chain has been
cleaned thoroughly and that any chain showing
evidence of broken rollers has been discarded.
Primary Chain Adjustment
The separate gearbox design of the Commando permits
adjustment by the medium of pivoting the gearbox on
the bottom bolt and there is no necessity for a slipper
type tensioner. Due to the high power output of the
Commando and Combat engines the correct adjust-
ment procedure must be followed to prevent subse-
quent gearbox movement in service. Proceed as
follows :
1 Check the total up and down movement on the
primary chain top run. This is felt by the finger
when the upper centre inspection cap is removed
from the chaincase. If incorrect, proceed to (2).
2 Slacken the gearbox top fixing bolt “B” (see
Fig. C51). Note that nut on left is captive and
must not be turned.
3 Slacken the nut on the gearbox bottom bolt.
4 Slacken the front nut on the adjuster eyebolt, two
or three turns.
5 Tighten the rear nut on the adjuster eyeboit until,
with the finger, the chain can be felt dead tight.
6 Now slacken off the rear nut and carefully tighten
the forward nut until there is total up and down
movement of 3 in. (9-5 mm).
7 Tighten securely the rear nut to lock the assembly
and recheck the adjustment in at least three
places. Should there prove to be a tight spot,
readjust to total up and down movement of # in.
(9-5 mm) at this point.
8 Tighten the gearbox bottom bolt nut. Lubricate
the thread of the gearbox top mounting bolt, fit
the nut and secure to 70 Ib. ft. (87 in. Ib.,
9.678 kgms.) torque from the right side. Note:
On 1972 and later models, do not attempt to turn
the nut at the left side of the top bolt — this is
spigotted to prevent movement.
_ Engine/Primary Transmission €
A PRIMARY CHAIN
ADJUSTER
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Fig. C51 Primary chain adjustment points
Rear Chain Adjustment
This adjustment is made by movement of the rear wheel.
ON Fig. C49 shows the adjustment points. Proceed as
= follows :
1 Slacken the rear wheel spindle nuts (A).
2 Release the chain adjuster locknuts (B).
3 Pull downwards on the bottom run of the chain
to bring the spindle hard up against the adjusters
(C).
4 Turn each adjuster an equal amount until, with
the rider seated, there is a total up and down
movement, measured in the centre of the bottom
— chain run of i in. to 1 in. (19-05 to 25-4 mm).
5 Tighten securely the adjuster locknuts (B).
6 Tighten the wheel spindle nuts and recheck the
adjustment in at least three places. Should there
prove to be a tight spot, readjust to give the correct
up and down movement at this point.
7 Finally, recheck rear brake adjustment as in
Section H13.
E BRAKE CAM GREASE
NE NIPPLE A
REAR CHAIN
ADJUSTER(C)
WHEEL SPINDLE
NUT (A)
ADJUSTER м
Fig. C52 Rear chain adjustment
|
Gearbox
ha
-
+
=.
+5
ик
7
Gearbox
Gearbox
SECTION D1
GEARBOX DESCRIPTION
The transmission (gearbox) is a self contained 4 speed
unit, completely separate from the engine crankcase and
thus simple and inexpensive for servicing. A robust
aluminium alloy casing with separate inner and outer
covers contains a gear cluster of extra tough nickel
chrome steel. Selection is foot controlled through a
positive stop mechanism to a rotating cam plate.
Hardened steel selector forks operated by the camplate
position the gear pinions.
The kickstart drives through an internal ratchet on the
layshaft first gear which in turn drives the mainshaft
and clutch.
SECTION D2
GEARBOX DISMANTLING
It is not necessary to remove the exhaust system whilst
giving attention to the gearbox, providing the gearbox
is not to be removed from the engine plates.
SECTION D3
REMOVING GEARBOX OUTER COVER
Prior to gearbox dismantling it is recommended that the
gearbox should be drained into a suitable sized drain
tray using the drain plug at the bottom rear of the gear-
box casing. Proceed then as follows:
1 Remove the kickstart by releasing the single
securing bolt. The bolt locates into a groove in the
kickstart spindle and thus it is necessary to remove
this bolt completely. …_
pr
2 If the battery is still, connected, disconnect by
removing the fuse before proceeding to the next
operation.
3 Remove the two nuts and one- bolt securing the
right hand footrest and note that the bolt also
secures the red earth lead tag. from behind the
footrest mounting plate. — *” 4
A nut without washer is used on the footrest
securing bolt. It is vitally important during
re-assembly not to overlook the refitting of this
earth lead or otherwise a short circuit may result
in the fuse being blown, or damage # the Zener
diode. |
MN Ea.
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4 Remove the gear indicator pointer from the gear
shift spindle. This is secured by a set screw and
plain washer.
Do not remove the gear shift lever at this time.
Remove the five cheese headed set screws from
the gearbox outer cover.
7 Remove the two screws securing the outer cover
inspection cap which may then be lifted away
complete with gasket.
8 Disconnect the clutch cable from the fork within
the gearbox outer cover.
9 Place the oil drain tray under the gearbox, and,
using the shift lever as a handle, pull the outer
cover off. It may be necessary to tap the cover
gently to free it.
10 Withdraw the shift ratchet plate and spindle.
SECTION D4
REMOVING GEARBOX INNER COVER
Prior to removing the gearbox inner cover it is necessary
to mark clearly the position of the clutch operating body
by two punch marks which are shown in Fig. D7. This
is due to the fact that the clutch operating body has no
positive rotational location. Proceed as follows:
1 Remove the small lever, screw and nut securing .
the clutch operating arm and collect the arm,
roller and bush.
2 Remove the clutch operating body locking ring as
in Fig. D1 and lift away the clutch operating body
and the ball.
Fig. D1 Removal of clutch body lockring. Note alignment
marks on lock ring and cover
Gearbox
3 Prevent the gearbox from turning by engaging top
gear as follows and applying the back brake fully.
Top gear can be engaged by levering the end of
the quadrant carefully to the top of the window in
the gearbox inner cover whilst rocking the rear
wheel. At this stage the mainshaft nut can be
removed.
4 In order to remove the gearbox inner cover it will
be found simpler to revert to the neutral position,
again by moving the end of the quadrant down the
window.
5 Remove the seven securing nuts to the gearbox
inner cover. These nuts are all of equal size, five
within the case and two outside.
6 Remove the gearbox inner cover, if necessary
tapping the end of the mainshaft to ease separa-
tion.
The inner cover should then be lifted away, com-
plete with kickstart spindle, with the pawl
assembled and also the return spring.
SECTION D5
DISMANTLING GEAR
PLATE
CLUSTER AND CAM
To dismantle the gearbox further it is necessary to
remove the clutch from the gearbox mainshaft and if the
sleeve gear is to be removed from the gearbox, the
countershaft sprocket must also be removed. Clutch
removal is covered in items 1 to 9 of Section C13 and
C14 and countershaft sprocket removal in Section D8.
4 Remove the clutch locating shims, the clutch
locating spacer, and circlip from the mainshaft end.
Remove the low gear pinions from the shafts.
Unscrew the selector fork spindle and remove.
Remove selector forks and withdraw mainshaft
with gears.
8 Withdraw the layshaft with gears. If the shaft is a
tight fit in the bearing heat the case and withdraw
the shaft complete with bearing. The bearing can
then be removed to complete disassembly.
Remove countershaft sprocket (Section D8).
10 Remove sleeve gear by tapping gently through the
bearing into the gearbox.
11 Remove the acorn shaped detent plunger spring
bolt. This will release the camplate detent plunger
and spring.
D _
12 Remove the two bolts and washers securing the
camplate and quadrant to the gearbox shell.
13 Remove camplate and quadrant and collect
“0” -rings.
14 Withdraw the sprocket spacer from inside the
countershaft oil seal.
15 The bearings can be withdrawn for inspection &quot;E
replacement by gently heating the case and
tapping the open end on a soft wooden surface.
16 Prise out the countershaft oil seal.
SECTION D6
INSPECTION OF GEARBOX PARTS
After cleaning all components very thoroughly such as
in gasoline (petrol) or kerosene (paraffin) check all
items thoroughly as below :
1 Inspect the two mainshaft and one layshaft ball
journal bearings for roughness indicating ball or
ball track damage on either the inner or outer
races. Feel for side play between the inner and
outer races. If the bearings are in good condition,
such play should be negligible.
2 Inspect both the layshaft and mainshaft for wear
on the splines, damage to the threads, out of truth
and severe wear and grooving on the bearing
diameters.
3 Inspect all pinions for chipping or obvious wear
to the teeth. Ensure that the dogs are not badly
rounded and that the inner splines are a satisfactory
fit to the shafts. Bushed pinions should be
offered to the shafts and checked for excessive
wear by aftempting to rock them on the shafts.
“o a
4 Inspect the gearbox shell and gearbox inner cover 040480 Sprocket 19 teeth
bushes for obvious wear. Note that wear on the
bushes in the shell supporting the camplate and 060931 Sprocket 20 teeth
quadrant can result in bad gear indexing and a
tendency to jump out of gear engagement. 060721 Sprocket, 21 teeth
5 Inspect the selector forks and mating grooves in 060759 Sprocket 22 teeth
the sliding pinions for sei . |
9 pinions tar selzure or wear 063420 Sprocket — 23 teeth
6 Especially in cases of bad selection, inspect the
Sprocket 24 teeth
camplate tracks for wear or distortion and ensure
that the camplate spindle is a good fit in the bush
in the gearbox shell.
063421
Changing the countershaft sprocket
~~
~~ -* SECTION D7 | 1 Remove the outer primary chaincase, clutch and
&gt; | primary transmission and inner primary chaincase
&agrave;, &quot;REMOVAL OF GEARBOX COMPLETE as in Section C14 to gain access to the sprocket.
-
Though not normally necessary during overhaul, we 2 Remove set screw and lockplate from sprocket.
recognise that circumstances may arise which make it
desirable to remove the complete gearbox without dis- |
turbing the engine although the primary transmission 3 The sprocket must be prevented from turning
must be dismantled fully. In these circumstances remove
the rear three crankcase to engine plate bolts (or studs,
depending on year), the rear wheel and on 1971 and
later models, support the motorcycle by the lower frame
rails on a strong box and remove the centre stand.
Remove completely the gearbox top and bottom mount-
whilst the left hand nut is released. If the gearbox
is in the frame, leave the rear chain connected and
apply the rear brake fully. If the gearbox is out of
the frame, pass a length of chain round the
sprocket, holding the ends securely in a vice.
ing bolt and stud and remove the drawbolt assembly 4 Noting that the sprocket nut is /eft hand threaded,
from the right hand side of the rear engine mounting and remove the nut and lift the sprocket clear.
turn the gearbox anti-clockwise in the engine plates
viewed from right side. Force the rear engine mounting |
rearwards until the cutaway part at the bottom right 5 Before refitting the sprocket, ensure that the
hand side is clear of the crankcase. The gearbox can sprocket spacer is in place on the sleeve gear
then be turned further and withdrawn horizontally from bearing sleeve.
the right hand side. Only in isolated cases will it be | | |
necessary to take out the front mounting main bolt to 6 Place the sprocket in position and if necessary tap |
provide still further working space. fully home with a tube drift. E.
иж |
7 if the original lockplate has been scrapped in
SECTION D8 removal, have a new one available. |
COUNTERSHAFT (GEARBOX FINAL DRIVE) | |
SPROCKET 8 Fit and tighten the left-hand nut fully, whilst
preventing the sprocket from turning. 7
| F
The countershaft sprocket is mounted on the mainshaft .
sleeve (high) gear and secured by a tab washer and 9 Secure the lockplate with the locating screw.
L.H. threaded nut. The Commando overall gearing
should be varied by changing the sprocket size. For the 10 Refit the inner chaincase, primary transmission
road going editions of the Commando, the following
sprockets are available: a&raquo;,
and. outer chaincase as in Section C34 and fit and
connect the rear chain.
Gearbox
SECTION D9
REFITTING GEAR CLUSTER AND
SELECTORS
After inspection of components as in Section D6 com-
mence reassembly as follows:
1 Heat the gearbox shell and press the sleeve gear
and layshaft bearings fully into position.
2 Fit the sleeve gear bearing seal squarely into the
housing, lipped side first.
Fit detent plunger, spring, and acorn nut loosely.
4 Fit the quadrant with “O -ring and secure with
bolt and washer.
a
Says
# = @ &gt;
Fig. D2 Location of camplate to index plunger. Knuckle end
of quadrant is aligned to top front cover stud
5 Lift the knuckle end of the quadrant until the top
inside radius is directly in line with the top front
cover stud (see Fig. D2), fit the camplate and
sealing ring, engaging the teeth of the quadrant
and camplate so that the notched edge of the
camplate is towards the gearbox sprocket and the
smooth edge towards the gearbox inner cover, the
last notch at the bottom engaging with the cam-
plate index plunger (see Fig. D2).
6 Secure the camplate with “O-ring, washer and
bolt.
Fig. D3
10
11
12
13
14
15
16
17
18
19
20
Tighten detent plunger acorn nut.
Fit the countershaft (sleeve gear) through bearing
and seal. Fit sprocket spacer in place inside seal.
Fit countershaft sprocket (Section D8).
Fit mainshaft through sleeve gear.
Fit the 3rd gear free pinion and bush to the layshaft
(dog side first to face out of assembled gearbox).
Fit the fixed high gear pinion to the layshaft, flat
side first (toward 3rd gear pinion). The shoulder is
to fit against the bearing.
Push the layshaft into the bearing in the gearbox
shell.
Assemble the mainshaft 3rd gear with selector
fork to the mainshaft (selector fork groove side
outwards) and engage the pin with the inboard
cam track (see Fig. D4).
Assemble the main shaft 2nd gear with bush to
the mainshaft, dogs inwards.
Assemble the layshaft 2nd gear with selector fork
(selector fork groove side inwards) and engage
the pin with the outboard cam track.
Fit the selector fork spindle through the selector
forks and screw home into the gearbox shell.
Fit the layshaft 1st gear.
Fit the mainshaft 1st gear with shoulder outwards.
Since the quadrant roller cannot be fitted after the
inner cover is fitted, it is imperative that the roller
is fitted into the quadrant knuckle at this time.
_ Gearbox — CD
CREO
A
Ze о а
; &gt; y Bad pa dan us ;
Fig. D4 Gear layout
SECTION D10 | | : ВЕ
REFITTING GEARBOX INNER COVER &raquo;
Ensure that the gearbox inner cover is clean on both y
inner and outer joint faces prior to assembly. Proceed as
follows:
1 Fit the inner cover gasket.
2 If the kickstart spindle has been removed from the
gearbox inner cover, it must be refitted at this stage.
Assemble the kickstarter spindle to the inner Fig. D5 Showing kickstart pawl stop on inner cover
cover, ensuring that the pawl is behind the stop on
the inner cover as shown in Fig. D5.
E:
я &deg;
3 Assemble the kickstart return spring, aligning the 4 Fit theiinner cover gasket and hold in place with
outboard end of the spring with the mating hole grease.
in the spindle and sliding the spring down until the
spring engages in the hole. Wind the spring as “5 Ensure that the two shafts are fully home prior to
illustrated in Fig. D6 to tension and engage on the attempting to assemble the inner cover to the
spring anchor pin. gearbox shell. -
A x
Gearbox
10
Assemble the inner cover, ensuring that it enters
over the location dowels, and fit snugly home dur-
ing assembly, at the same time guiding the cover
over the unsupported outboard end of the selector
fork spindle.
Fit the seven nuts securing the inner cover, noting
that two of these fit outside the casings. The seven
nuts should be tightened to a torque setting of 10
to 15 ibs./ft. (1-383 to 2:074 Kg/m).
Engage top gear, apply the footbrake, and tighten
the gearbox mainshaft nut to a torque reading of
70 Ibs./ft. (9:678 Kg/m).
Assemble the clutch operating lever body com-
plete with lock ring and ball to the gearbox inner
cover.
Tighten the operating lever body ring until the
body is fully engaged and finally tighten the lock
ring to bring the body slot directly into line with
‘the marks previously applied to the boss in the
cover. Fig. DG illustrates the alignment procedure
during tightening of the lock ring. If a new cover
is being fitted and no alignment marks are present,
hold the body in the position where the clutch
cable can exert a straight pull, as the lockring is
tightened.
; , TES N
Fig. D6 Kickstart spring located. Note alignment of clutch body
| to permit straight pull on clutch cable and operating le ver:
‘11 Assemble the withdrawal lever, roller, bush and
pivot screw and secure the lock nut. Assembly
should be in accordance with Fig. D7.
12 Assemble the ratchet plate and spindle, locating
the peg into the knuckle pin roller. Ensure that the
‘O’ ring is fitted to the ratchet plate spindle.
Fig. D7 Order of assembly of clutch withdrawal lever
SECTION D11
DISMANTLING AND RE-ASSEMBLING
GEARBOX OUTER COVER
To dismantle the outer cover, remove the paw! carrier
assembly and press the pedal spindle from the outside
of the cover to disengage the spring peg from the legs
of the pedal return spring. The pedal stop plate set
screws can now be removed and the stop plate lifted
away, complete with spring.
Xx
De A
Gearbox
Fig. DE Pawl carrier, spring and ratchet plate assembled
During re-assembly ensure that the spring retaining
washer is fitted over the main spindle of the pawl
carrier and that the spring has been assembled over the
tatchet plate as illustrated in Fig. D8. Tighten the stop
.aNate set screws and assemble the splined end of the
pawl carrier past the ‘0’ ring in the cover. Locate the
spring peg between the legs of the spring and push the
pawl carrier fully home, engaging between the legs of
the spring. Check the carrier action and that the spring is
correctly located. The set screws should be tightened
- only when the action of the pawl carrier has been
checked for full freedom of movement. Now fit the
pawl spring with its double cranked leg downwards,
ensuring a minimum but perceptible clearance, between
the two legs of the spring and the pawl. &copy;
SECTION D12 7
REFITTING THE GEARBOX OUTER COVER
Having dealt with the outer cover as described in Sec-
tion D11, ensure that the joint facing is perfectly clean
and proceed with assembly as detailed below :
o - po
a PALIAR 7 5
ai Tan Fer LR ВЫ .
Fit the inner cover to outer cover gasket, retaining
in place during assembly with a smear of grease.
Ensure that the gasket engages satisfactorily over
the cover dowels.
To ensure cover alignment during assembly, retain
the ratchet spring in the central position with the
index finger of the right hand and guide the case
over the kickstart shaft with the thumb of the left
hand engaged through the filler cap hole.
Drive the outer cover fully home and assemble the
five screws of equal length to retain the outer
cover in position. If the cover is very difficult to
push into position, check whether the pawl! has
rotated due to the pawl scissor spring not having
been held securely in position, during final as-
sembly. The cover should be removed, the ratchet
pawl reset and re-assembly undertaken.
Fit the gearshift pedal and kickstart crank, then -*
check the action of the gearbox, rotating the rear
wheel as the gear pedal is moved to the various
gear positions.
If all is well, assemble the gear position indicator
pointer and replenish the gearbox with oil.
Connect the clutch cable through the inspection
hole in the gearbox outer cover, engaging and
locating the nipple in the operating lever. oo
/
Finally assemble the gasket, inspection cover and
screws to the gearbox outer cover, and check the
security of the drain and level plugs.
— Carburetor
Carburetor
Carburetor
SECTION E1
DESCRIPTION
The Amal concentric float carburetor proportions and
atomises the correct amount of fuel, mixing it with the
air drawn in through the air intake. The jet sizes, choke
bore, throttle needle, and throttle slide cut away ensure
that the correct fuel/air mixture is maintained at all
throttle openings. Initial opening of the throttle brings
into operation the mixture supply from the pilot jet
system which controls the idling speed. As the throttle
is progressively opened the mixture supply is aug-
mented from the main jet which discharges through the
~CABLE ADJUSTER
CABLE ADJUSTER LOCKNUT
SECURING SCREWS,
MIXING CHAMBER TOP
AIR VALVE GUIDE
THROTTLE VALVE SPRING
AIR VALVE SPRING -
NEEDLE CLIP
THROTTLE NEEDLE
AIR VALVE
THROTTLE VALVE
TICKLER
AIR INTAKE TUBE — Ml
PILOT JFT ~— =
(CAPTIVE)
oy
PILOT AIR ADJUSTING SCREW
SPRAY TUBE
NEEDLE er 7&quot;)
&quot;THROTTLE STOP ADJUSTING SCREW
JET HOLDER
MAIN JET
pa
FLOAT u A y
€ N FLOAT SPINDLE
&Agrave;
Tm
т | HLoar
— FLOAT CHAMBER WASHER
SECURING SCREWS ——— FLOAT CHAMBER BODY
FILTER — - 1
N98
Fig. ET Amal concentric float carburetor
needle jet into the primary air chamber and goes from
there as a rich fuel/air mixture through the primary air
choke into the main choke. The earlier stages of the
throttle opening are controlled by the throttle cut away
and the taper needle which passes through the needle
jet, the taper allowing more fuel to pass through the
needle jet as the throttle is opened.
Type 930 Amal concentric carburetors are fitted to early
750's. Type 932 Amal concentrics of 32 mm bore size
are fitted to Combat engine 750's, other late 750's, and
850's. An exploded layout (illustrating both types) with
part descriptions is shown in Fig. E1. A common airbox
serves both carburetors, this being covered in detail in
Section E9.
SECTION E2
CARBURETOR REMOVAL
For ease of handling it is recommended that the car-
buretors are removed attached to the spacers as a pair
as follows:
1 Disconnect the fuel lines from both fuel taps.
2 Remove four socket screws and washers securing
. the spacers to the head — a shortened socket key
is needed for ease of access.
3 With the balance pipe and cables still connected,
lift the carburetors and manifolds away from the
cylinder head, disengaging the flexible air hoses at
the same time. To service the carburetors indi-
vidually :
4 Disconnect the balance pipe at one end.
5 Remove the two cross head screws and washers
securing the carburetor top.
6 Lift off the carburetor top. throttle and air slides
with cables attached.
The top and slides can be left hanging from the
cables but the exposed parts should be protected
from damage by wrapping in clean cloth.
7 If required, remove the second carburetor in
similar fashion, removing the fuel line by taking off
the banjo bolts.
Carburetor
SECTION E3
CARBURETOR DISMANTLING
The carburetor as detached from the motorcycle is par-
tially dismantled, in that the mixing chamber top and
both throttle and air slides have been removed. If the top
and slides are to be removed from the cables, proceed
as follows:
1 Lift the throttle return spring, note the groove in
the needle to which the clip is engaged then remove
the clip. Collect the needle.
2 Disengage the throttle cable nipple and collect the
throttle valve.
3 Lift the air valve cable and spring, disengage the
cable nipple and collect the air valve.
4 The top is now free to be lifted clear. Dismantling
of parts from the mixing chamber should proceed
as follows:
5 Remove the two screws securing the float
chamber to the carburetor body and collect the
float chamber complete with float and float needle,
also the joint washers.
6 The float and float needle are manufactured from
white nylon. Lift the float, float needle and float
spindle clear for later examination and drain the
float chamber.
7 Remove the main jet, needle jet.
SECTION E4
EXAMINATION OF CARBURETOR PARTS
The following parts should be examined and replace-
ments made where necessary:
Float: Check for leakage — fuel can be seen in the float
if this condition exists. Check also that the float
needle fits securely.
Float Needle: Check for wear on the seating taper.
Main, Needle and Pilot Jets: Examine for damage
and blockage — never use wire to clear a blockage but
instead use compressed air.
E
Throttle Valve: Remove any burrs and burnish care-
fully any scores. Deep scoring renders the valve unfit
for re-use.
Throttle Needle: Ensure the needle is not bent or
worn badly on the taper. Check that the clip grooves
are clear and “sharp.”
Carburetor Body: Blow out all internal galleries with
compressed air. Check that all threads are sound.
Examine for excess wear on the throttle valve bore.
Pilot Air Screw: Check for wear on the taper.
SECTION E5
CARBURETTOR REASSEMBLY
Assuming all parts are clean and in sound condition
commence reassembly as follows:
7 Using new friction ‘O’ rings on both screws if the
originals have deteriorated, refit the pilot air screw
and throttle stop screw.
8 Fit the needle jet to the jet holder and jet holder to
the carburetor body.
9 Fit the main jet.
10 Position the float, with float needle and spindle, in
the float bowl. |
11 If the original is damaged, fit a new float bowl
joint washer ensuring it is the correct way round
with the holes aligned to the jet passages in the
bowl.
12 Fit the complete float bowl and secure with the
two screws and washers.
Where the originals have deteriorated, replace the ‘O&deg;
ring in the mounting flange of both carburettors and
couple the carburetors to the manifolds, securing with
two nuts and plain washers for each instrument. Con-
nect the balance pipe to both manifolds. If the air and
throttle valves and mixing chamber.tops have been
detached from the control cables, they should be
re-connected as follows:
Carburetor
13
14
15
16
17
18
19
20
21
22
23
24
25
Place the air valve guide tube and spring over the
air cable (the brass guide assembles with the
flanged end towards the cap).
Compress the spring to expose the maximum of
inner cable then pass the nipple through the air
valve to engage at the bottom.
Place the throttle valve spring over the throttle
cable and compress it.
Feed the throttle cable nipple through the throttle
valve centre hole then engage the nipple in the
adjacent hole.
Fit the needle clip to the correct groove.
Compress the throttle spring to clear the throttle
valve then place the needle and clip into the
throttle valve from the top with the needle in the
centre hole of the slide. Release the throttle
spring and ensure that the spring fits over the
needle clip.
Locate the air valve into the channel of the throttle
valve. The carburetors with manifolds are ready
to refit to the cylinder head. Proceed as follows:
Offer the throttle and air valves, assembled to the
cables and tops to both instruments. Ensure that
the throttle needle passes easily through centre
hole of the body and that the key on the throttle
valve mates with the keyway in the carburetor
body. Ensure that the return spring fits over the
abutment in the top.
Secure each carburetor top with two cross headed
screws and washers.
Mount the carburetors on the cylinder head using
the heat insulators between the manifolds and
cylinder head. Secure with socket screws and
washers.
Reconnect the fuel pipes to both petrol taps.
Fit both carburetors to the airbox flexible connec-
tors and take great care that these locate bothin the
airbox front plate and over the carburetor intakes.
Reassembly is now complete and slack should be
taken up in the control cables and the carburation
adjusted as in Section E7.
SECTION E6
FUEL TAPS
Twin taps are fitted. The one on the right side provides
the reserve supply and is recognised by the lack of a
stand pipe inside the tank. Fibre washers seal the taps
to the tank and must be checked that they are un-
damaged before being re-used.
SECTION E7
CARBURETOR ADJUSTMENT
Adjustment should be carried out in the sequence des-
cribed below with the engine at operating temperature.
The exhaust system to be used must be fitted and
preferably the test should be carried out on a slight up
grade so that the engine is pulling. The air lever must be
fully to the tight wire position before adjustment takes
place.
1. Main Jet — Throttle threequarters to full open.
If at full throttle, the engine runs “heavily” the main jet
is set too large. If by slightly closing the throttle valve,
the engine power seems to improve, the main jet is too
small. With a main jet of the correct size the engine
should run evenly, and be delivering maximum power at
full throttle.
The appearance of the sparking plug is one of the
best indications of mixture strength. To check, set the
carburetors to shut off completely on closing or false
readings will be obtained, then run the machine at full
throttle over the test course, declutching and stopping
the engine quickly. Then examine the spark plugs. If
the plugs have a cool appearance with the central
insulator free from loose black carbon and a light
chocolate colour on the insulator, the mixture is correct.
A rich mixture will be indicated by a black, wet oily
appearance with deposits on the central insulator. Weak
mixture will be indicated by a dry whitish deposit and
the points may appear to have been overheated.
2. The Pilot Jet — Throttle up to one-eighth open.
Set the engine to run at a fast idling speed with the
throttle shut by using the throttle adjusting screw. Turn
this screw outwards until the engine runs slower and
begins to falter, then screw the pilot air adjusting screw
in or out to make the engine run more evenly and faster.
If the idling speed is still too fast reduce it by means of
Carburetor
the throttle adjusting screw and again adjust the pilot
air adjusting screw until the idling is satisfactory.
Note: When new or re-assembled carburetors are used
start with pilot screw 14 turns out from the fully-in
position.
3. Throttle Cutaway -— Throttle one-eight to one-
quarter open.
If, as the machine pulls away from the idling position,
there is spitting back from the carburetors, slightly
richen the mixture by screwing in the pilot air adjustirg
screw slightly. If this is not effective, return-the screw
to its former position and fit a throttle slide with a smaller
cutaway. If, with the throttle in this position, the engine
jerks under load and there is no spitting, either the jet
needle is much too high or a throttie slide with a larger
cutaway is required to cure richness.
4. Throttle Needle — Throttle one-quarter to three-
quarters open.
The needle controls a wide range of throttle opening
and therefore the acceleration. Placing the needle in
the lower position, that is, with the clip in the top
groove gives a weaker mixture. Placing the needle in
the higher position, that is, with the clip in the bottom
groove, richens the mixture. If the mixture is too rich
with the needle in the lower position, the needle jet
should be replaced and if the needle itself has had a great
deal of use, replace it also.
5. Pilot Jet
Check again pilot adjustment as the last operation.
SECTION E8
ADJUSTMENT FOR ALTITUDE
It is necessary to adjust carburation on a motorcycle
operated continuously in altitudes greater than 3,000
feet approximately. Motorcycles as supplied from the
factory are already equipped for correct carburation up
to 3,000 feet. |
The main jet requires a reduction in size of 5 per cent
at altitudes between 3,000 and 6,000 feet. Beyond
6,000 feet further reductions of 4 per cent should be
made. я
Altitude adjustments should only be made if the
motorcycle is used permanently at high altitudes. It is
not necessary to adjust merely for a journey through
mountainous areas.
SECTION E9
TWIN CARBURETOR ADJUSTMENT
It is necessary periodically to synchronise the car-
buretors so that they open and close simultaneously.
Start with the handlebars in the centre position so that
there is no “pull” on the throttle cable which will inter-
fere with adjustment. Proceed as follows:
1 Take up any slack in the throttle cables using the
adjuster on the top of each mixing chamber, then
tighten the adjuster locknuts.
2 Start the engine — this must be thoroughly
warmed up before adjustment commences.
3 Follow the main adjustment sequence in Section
E7 before setting slow running. It is all-important
to have both throttle valves opening simulta-
neously. To ensure that this is the case, the twist-
grip should be set to allow the engine to run
fractionally over idling speed. Gently screw in
the throttle stops in that position. Return the twist-
grip to the closed position so that the engine runs
on the throttle stops. Now proceed as follows:
4 Lift off one spark plug lead and commence setting
the carburetor on the other cylinder as a single unit.
5 Adjust the pilot air screw and stop screw on the
cylinder which is firing.
6 Reverse the process by replacing one plug lead and
removing the other.
7 Adjust the pilot air screw and stop screw on the
second cylinder.
8 Replace the plug lead — at this stage tickover may
be too fast. If so, lower both throttle stop screws by
an equal amount until idling is correct. Ensure there
is about $” (3 mm) slack in throttle cable. This
slack must be equalized so that throttles open
together.
Carburetor E
SECTION E10 5 The element should be cleaned as described below
or replaced.
Reassembly is a reversal of the dismantling
AIR FILTER procedure,
The airbox comprises a detachable front plate, per-
forated metal band and replaceable automobile type air
filter element, the backplate being mounted directly on
to the front of the battery tray.
Removing and Refitting the Element:
в 1% 0
НН
REN НН uy
HO
se
E
1 Take out the two bolts securing the air filter front SN
plate. |
Fig. E2 Removing air filter element and gauze band
2 On Fastback only, remove the accessory cover to 9 9 9
provide clearance
3 Lever the front filter plate outwards at the bottom
and clear of the perforated band and element. Cleaning the Air Filter Element:
Models with the power socket attached to the
front plate need not have the socket disconnected. 2.
Р Whilst stressing that the pleated, resin impregnated
paper element is replaceable and should therefore be
changed for a new one and when it is badly clogged,
the life of the element can be prolonged by superficial
cleaning. After removal, taking care not to deform the
4 As shown in Fig. &pound;2, remove the gauze band element, tap it on a bench to dislodge as much foreign
together with the element. matter as possible, then blow clear with compressed air.
Frame and Ancillaries
Frame
and
Ancillaries
Frame and Ancillaries F
SECTION F1
REMOVAL OF POWER UNIT
In some types of repair, for example, during an accident
repair, where the frame must be changed, it is desirable
to remove the engine/gearbox/primary drive and engine
plates as a group. To remove this assembly, proceed as
below :
1
Release the large side knobs and lift the seat off
upwards and to the rear (Fastback seats lift
straight upwards).
Turn the ring of the twist fastener to release the
forward end of the accessory cover and lift the
cover forward off the rear mounting pegs.
Disconnect the battery by removing the fuse from
the fuseholder adjacent to the battery.
Remove the right side panel which is secured by
two screws at the top and a peg and rubber at the
bottom.
Remove the fuel tank (Section F9).
Remove both exhaust pipes with mufflers by
releasing the tab washers at the finned lockrings
and unscrewing the lockrings using service tool
063968. Remove the nuts and washers holding
the muffler bracket to the two mounting rubber
studs and lift each system away in turn.
Disconnect the rear chain at the split link and
remove the chain completely.
Disconnect the rear brake cable from the expander
lever by removing the adjuster nut completely and
depressing the rear brake pedal so that the end of
the cable clears the trunnion. Collect the trunnion.
The swinging arm must now be removed. The pivot is
lubricated by SAE 140 oil and provision must be made
to collect the oil released as the end cap is removed.
Proceed as follows:
9
10
Unscrew the pivot end cap screw and lift the end
cap, washers and long screw away together.
Whilst allowing oil to drain from the pivot, remove
the rear wheel (see Section H1). Pre 1971 models
may have the wheel removed complete with
sprocket and brake. On 1971 and later models
remove the wheel only, leaving the sprocket and
brake assembled to the swinging arm.
11
12
13
14
15
16
Fig. F1
Lift away the right footrest complete after removing
two set screws or nuts of the same length, and one
bolt, the nut for which secures also the ground
(earth) tag for the Zener diode.
Disconnect the flexible rear chain oiler tube from
the metal oiler pipe at the swinging arm.
Remove the suspension unit bottom bolts.
Take out the swinging arm pivot spindle. This is an
easy sliding fit but is secured by a lock screw on
top of the pivot tube which must be removed. It
will be noted that the pivot spindle is threaded
internally to aid removal. Screw a bolt with locking
nut into the thread (the main front mounting bolt
will be ideal) tighten the nut and twist and pull
the spindle gently out.
Lift away the swinging arm complete with chain-
guard. Collect the left end plate and ‘O’ rings.
Disconnect the tachometer cable (at the top front
of the crankcase).
Removing oil junction block securing bolt
Frame and Ancillaries
17
18
19
20
7
Fig. F2
Dismantle the engine steady (see C1) by
removing the nuts and washers from the rubber
mountings first, to prevent them turning in the
frame. Release the two studs and lift away with the
side plates. Remove the main engine steady plate
by taking out the three socket screws and
washers. Note that the centre screw secures the
ground (earth) lead tag.
Remove the rocker feed pipe after taking out the
three banjo bolts. Collect the copper washers for
re-use.
Release the coil cluster from the frame as an
assembly (on pre 1971 models two bolts are
used: on 1971 and later models, four bolts are
used). Disconnect the H.T. leads at the sparking
plugs then tie the cluster clear of the engine unit
with all other leads still attached.
Detach the carburetors from the cylinder head
complete with manifolds and balance pipe. Either
removal or refitting of the securing screws is
facilitated by the use of a shortened socket screw
key. Lay the carburetors and manifold assembly
still attached to the throttle and air cables over the
headlamp clear of the engine unit.
Lifting out power unit to right side
21
22
23
24
25
26
27
28
F
Disconnect the contact breaker leads from the main
harness in the area of the frame top rails.
Disconnect the oil tank end of the engine breather
pipe.
Place a receptacle of sufficient size to contain the
contents of the oil tank below the rear of the
crankcases, remove the bolt securing the oil junc-
tion block to the crankcases, pull the block and
pipes away from the crankcases and allow the oil
to drain. Alternatively after parting the junction
block from the crankcases, raise the junction block
and tie with wire to the airbox to prevent oil
draining from the tank, or protect the feed pipe
with cardboard and compress the pipe with grips
to prevent oil draining (see Fig. F1).
Slacken clutch cable adjustment and lift the cable
nipple from the handlebar control.
Remove the front engine mounting by taking out
the centre bolt, sliding back the left gaiter and
removing the mounting collar, plastic washer and
gaiter as a set. Remove the right gaiter etc. in
similar manner. Remove the two mounting-to-
crankcase studs (bolts on later models) and lift
away the mounting.
On 1971 and later models, remove the centre stand.
This is secured by bolts fitted from inboard. Lift
the spring clear as the stand is removed.
On pre 1971 models, remove the earth lead from
the side stand bracket to bottom crankcase stud.
Disconnect the two alternator leads at the snap
connectors.
The power unit assembly is now secured to the frame
only by the rear mounting. Before removing the rear
mounting stud, coil the clutch cable by the gearbox.
Unclip the C.B. leads from the frame and coil them by
the timing case. Protect the lower frame rails against
damage using-cardboard or thick cloth.
29 Support the weight of the power unit and use a
soft drift to drive out the rear mounting stud.
30 Collect the gaiters, collars, end caps and footrest
plate spacers.
31 As shown in Fig. F2, lift the power unit bodily
from the frame to the right hand side. Raise the
front of the power unit and lower the rear to clear
the airbox.
SECTION F2
ISOLASTIC ENGINE MOUNTINGS
The Norton Isolastic principle built into the Commando
couples together the engine, transmission, swinging
fork and rear wheel. This assembly, parted from the main
frame is seen clearly in Fig. F3.
Isolation of the engine transmission swinging fork
and rear wheel is achieved by the use of resilient mount-
ings shown as A, B and C. Unlike earlier attempts at
rubber mounting, the Commando is unique in that the
swinging fork is mounted on the engine cradle and thus
isolated from the main frame. This prevents twisting
between the engine and rear wheel sprockets under
load which would otherwise cause premature chain
wear or displacement of the chain.
- Frame and Ancillaries
The power unit in its mounting plates oscillates on
the rear mounting (B) which has three bonded and two
buffer rubbers. This arrangement provides maximum
support, particularly to the swinging arm and rear
wheel, whilst isolating the power unit from the frame.
The front mounting (C) controls the degree of move-
ment of the power unit on the rear mounting and the two
bonded and two buffer rubbers allow more flexibility
than does the rear mounting.
Both the front and rear mountings incorporate
plastic thrust washers to permit side play to be kept
within very restricted limits without transmitting engine
and transmission vibrations to the rider. The degree of
side play is controlled by shims to enable the figure to
be kept within design limits even after considerable , ii
mileages. 5,3
The engine head steady (A) completes the triangular
formation of the resilient mountings and controls lateral
movement of the engine unit in the frame. The insulating
rubbers are fitted between the side plates and frame
tube.
ZA
Фр [o
te 4
ZN
Fig. F3 Commando parted to show isolastic mounting points
ea
2
FE
чё
Frame and Ancillaries
604-77 -- 248-92 тт,
—
FO Tee
- E — ое — a)
VE | 7 | Е Е
363-47mm oi &gt;
N со x
LT &iuml; OL
e
a
1152-27mm Ÿ |
152-52mm | 1
He 214-32 тт =
(
221-99mm \ =
La 222-50mm |
BETWEEN REAR
PLATES
FRAME CHECKING DATA 850 MODELS
| | FRAME CHECKING DATA 750 MODELS
Fig F4 Frame checking charts 7
Frame and Ancillaries
SECTION F3
FRAME CHECKING DIMENSIONS
During the course of an accident repair, the frame must
be examined most carefully for damage to tubes, welds
and fixing lugs. It is then essential to check for distor-
tion and misalignment. Fig. F4 shows the Commando
frame measurements which should be used to establish
whether or not damage has occurred. However, before
stripping out the frame from the motorcycle, one quick
visual check can be made on vertical alignment at the
steering head tube after removal of the front fork
assembly. This is accomplished by a long tube (approxi-
mately 4 ft. (121 cm) ) inserted as a tight push fit through
the steering head races. Viewed from the front, the tube
should be seen to be perfectly aligned to the motorcycle
centre line. Severe damage will immediately be shown
up by this method and will obviate unnecessary dis-
mantling at the estimating stage.
It is recommended that the frame is checked more
accurately when removed from the motorcycle, to the
dimensions given in the checking chart.
SECTION F4
REFITTING POWER UNIT
Prior to refitting the power unit, if any major mechanical
attention has been given, wash the oil tank and oil pipes
out very thoroughly to remove dirt and foreign matter.
As with dismantling, protect the lower frame rails
against damage. Proceed as follows :
1 Pass the power unit into the frame from the right
side, raising the front slightly and lowering the rear
to clear the airbox.
2 With the power unit loosely in position, move the
rear end as far as possible to the right side of the
frame to facilitate assembly of the rear mounting.
3
Woop, LC
oli
. |‘ .. Tr.&quot;
Engin&eacute; mountings are covered in detail in Section
F12-17.
However, if the mountings have merely been dis-
mantled and are to be reassembled without varying the
shimming, proceed as follows :
3 Grease using silicone grease (such as Releasil No.
7) and place in position the shims and left side end
cap (the shims should be divided equally between
left and right).
4 Grease using a silicone grease and insert as a group
the left side gaiter, collar and plastic washer with
the gaiter held back for maximum clearance.
Note that the gaiter should be greased inside to
slide easily over the cap and mounting. The order
of assembly and method of holding the gaiter back
on the edge of the plastic washer are seen
respectively in Figs. F14 and F5.
N88
Fig. F5
Gaiter/ collar group ready to fit. Note gaiter held back
on edge of polyurethane washer
5 Position the spacer between the left hand alloy
footrest mounting plate and battery tray bracket
and slide in the mounting stud from the left side,
moving the power unit as necessary to align the
stud holes.
6 Grease using a silicone grease and fit the right side
shims and cap.
7 Grease (including inside the gaiter) and fit the
gaiter, spacer collar and plastic washer (see
Figs. F14 and F5).
8 Tap the main stud right through aligning with the
right frame bracket, insert the footrest plate
spacer, then fit the washer and nut. Tighten to
25 |bs./ft. (3-456 Kg/m).
Frame and Ancillaries
Fig. F6 Coil cluster from rear beneath
9
10
11
Fit the front engine mounting plates to the crank-
cases, sliding the long end of the mounting over
the lower crankcase bosses. With the stud or bolt
fitted, pivot the mounting up into position to insert
the second stud or bolt. Almost certainly the power
unit will need to be lifted to insert the crankcase
studs (or bolts).
Grease the components with a silicone grease and
reassemble the front mounting as in Section C32.
Tighten the centre bolt to a torque of 25 Ibs./ft.
(3-456 Kg/m).
Refit the oil pipe junction block, using a new
gasket if necessary and securing with the single
bolt which must not be overtightened.
E da 22€ -
A AA E ae
= ER LT Puta
.
IGNITION COIL
12
13
14
WARNING \
LIGHT ASSIMILATOR
IGNITION COIL.
SUPPRESSED HIGH
” TENSION LEADS
Prior to refitting the carburetors and spacers,
grease the manifold screws lightly and run them
into the cylinder holes to ensure that they can be
tightened by finger pressure only when the car-
burettors and manifolds are assembled. During this
operation and before attempting to fit the engine
to the frame block the inlet ports with clean non-
fluffy cloth to prevent a screw dropping down one
of the ports. Remember to remove the cloth before
fitting the carburetors.
Holding the Tuffnol insulating block in place
(some models use blocks with one flat edge which
must fit inboard) fit the air hose to the airbox using
a screwdriver blade to enter the lip, then assemble
the right carburetor and manifold to the head
tightening the socket screws completely.
Fit the air hose to the airbox, then offer the insulat-
ing block, carburetor and manifold to the cylinder
head, tightening the socket screws as far as possible
with the fingers. When locking up the screws an
abbreviated socket key is essential.
F
a
Frame and Ancillaries
15
16
17
18
19
20
21
Fit the main head steady plate to the cylinder head,
securing with three socket headed screws. Note
that the centre screw secures the ground (earth)
tab on the red leads.
Position the two spacer tubes in the head steady
plate and offer the side plates over the rubber
mounting studs. Pass the two studs through the
side plates and spacer tubes and secure with the
washers and nuts. Lastly, fit and tighten the nuts
at the rubber mountings.
Pass the rocker feed pipe behind the fuel line ‘T’
piece and between the manifolds. The double end
of the pipe fits to the right side of the rocker box.
Ensure copper washers are fitted to both sides of
each banjo and secure with the banjo bolts.
Refit the coil cluster, (the cluster is illustrated in
Fig. F6) and reconnect the contact breaker leads
colour to colour.
Reconnect the crankcase breather pipe at the oil
tank.
Reconnect the tachometer cable to the abutment
at the top front of the crankcase, ensuring that the
cable adaptor is fitted square upwards and that it
has engaged with the drive before the cable union
nut is tightened.
Reconnect the clutch cable at the handlebar con-
trol and adjust the cable to give # in. to + in. (4
to 6 mm) free play.
1971 and later models
22
23
Refit the centre stand with the pivot bolts passing
through the engine plates, spacers and stand,
inboard to outboard. Fit the nuts and tighten fully
on to the spacers.
Hook the long end of the centre stand spring into
the L.H. rear engine plate then use a length of
twine over the stand end of the spring to expand
it whilst locating the hook in the stand cross tube.
Е
Prior to refitting the swinging arm, ensure that the
pivot area is perfectly clean, that the sintered bushes are
oiled lightly and that the four ‘O’ sealing rings are in
position.
24
25
Fig. F7
26
27
The left side pivot end cap must be held or “stuck”
in position with a dab of grease as the swinging
arm is positioned (see Fig. F7). Push the swinging
arm forward so that the left end cap is held in
position by the inner chaincase.
Using a suitable bolt with locknut screwed into the
right end of the swinging arm pivot spindle, posi-
tion the lock screw hole upwards to align with the
pivot tube hole (see Fig. F8). Align the pivot
spindle with the swinging arm bore and push fully
home.
Swinging arm offered into position with end cap held
in place with grease
Align the lock screw hole in the pivot spindle and
mounting cross tube by movement on the bolt used
during refitting the spindle, locate and secure the
lock screw and washer. (see Fig. 9).
Remove the bolt and nut used during fitting of the
pivot spindle.
Frame and Ancillaries
28
Ensure the right side ‘O’ rings are still in position
then screw home the right end cap and extra long
thin screw with copper washer. During tightening,
position the lubrication nipple between the 11 and
1 o'clock position and check that the fibre washer
is in position beneath the nipple.
mi&raquo;
Fig. F8 Aligning swinging arm spindle with swinging arm bore
29
30
31
Refit the rear chain. This must pass over the bolts
within the chainguard and over the countershaft
(gearbox) sprocket. This is facilitated by engaging
top gear, tying the clutch lever back to the handle-
bar then cranking the kickstart to revolve the
sprocket and pull the chain over. Engage neutral
and pull the chain through sufficiently to connect
the bottom run. Release the clutch lever.
Push the rear chain oiler flexible pipe onto the
metal pipe at the swinging arm.
Refit the right footrest and secure — do not over-
look the ground (earth) tag secured to the longest
bolt from behind by a nut. |
TALLA : \ : X
Т
Fig. F9 Spindle lock bolt fitted
32 Refit the rear wheel (see Section H2).
33
34
35
36
37
38
39
Refit the exhaust system but check that the copper
sealing rings (corrugated steel rings on later
models) are in position in the ports and that lock-
ring tab washers are fitted. Tighten the lockrings
using service tool 063968 then tap the lockring
tabs as appropriate between the cylinder head and
lockring fins.
Adjust the rear brake as desired then adjust the stop
switch position (see Section J18).
Refit the fuel tank (see Section F9) and reconnect
the fuel pipes.
Refit the fuse.
Refit the accessory cover and right side cover.
Check all oil levels and top up or refill as necessary.
This includes the swinging arm pivot which
requires SAE 140 oil.
Replace the seat and secure with the knurled side
knobs.
Na
Frame and Ancillaries
SECTION F5
REMOVING AND REFITTING SUSPENSION
UNITS
In order to replace or dismantle the suspension units it
is necessary to remove them from the motorcycle as
follows:
1 Remove the nut securing the bottom of the sus-
pension unit and pull the unit clear of the swinging
arm.
2 Release both large knobs and lift the seat up and to
the rear (Fastback model straight up) clear of the
motorcycle.
3 Slacken off the knurled knob as far as possible to
gain spanner access to the integral hexagon of the
suspension unit top bolt.
4 Holding the bolt by the hexagon to prevent turning,
remove the nut and plain washer from behind.
5 Support the weight of the suspension unit and
remove the bolt.
The suspension unit is now free to lift clear of the top
frame lugs.
Refitting is a reversal of the foregoing but on re-
assembly ensure adequate clearance between the
suspension unit top collar and any carrier equipment
which may be fitted.
SECTION F6
REAR SUSPENSION UNITS (GIRLING)
The rear suspension units are of the spring controlled,
oil damped, telescopic type. Adjustment of static spring
loading is accomplished by rotating the three position
castellated cam ring at the bottom of the spring. To
adjust, support the motorcycle on the centre stand and
use a ‘C’ spanner to turn the cam ring. Turning the cam
ring to the left increases the loading to cope with
additional loads and vice versa. Both units must be on
the same loading — if in doubt, start both units from the
light load position. The damper units are factory sealed
thus cannot be serviced. The springs can however be
removed. Bonded rubber bushes are used top and
bottom for mounting the suspension units. These can be
pressed out for replacement and new ones pressed in,
smeared with a lubricant such as soap to ease entry.
SECTION F7
CHANGING THE SPRING
In order to change a spring it is recommended that the
suspension unit is gripped in a vice by the bottom
mounting. Turn the castellated cam ring to the light
load position. The help of a second operator is needed
so that as the spring is grasped firmly in both hands and
compressed down, the second operator lifts clear both
split collars. Pressure on the spring is now released and
the spring can be lifted clear. Reassembly is a reversal of
these instructions.
SECTION F8
REBUSHING THE SWINGING FORK
After long usage, where lubrication has been neglected
or where grease has been used instead of the recom-
mended SAE 140 oil, the two flanged bushes working
on the spindle may wear. After removal of the swinging
fork (Section F1(9-15) wash all parts very thoroughly in
gasoline (petrol). Insert the pivot spindle and check the
fit. Excessive working clearance will permit unaccept-
able side movement at the rear wheel and this must be
rectified by renewing the spindle, bushes and oil sealing
‘O’ rings. Renewal of these items should be dealt with
as follows: |
NE
Frame and Ancillaries
1 If not displaced during removal of the fork, lift out
the outboard ‘O’ rings (see Fig. F10).
2 Using a light press and a suitable shouldered press
tool, press out the first bush, releasing the large
‘0’ ring and dust cover.
3 Repeat for the second bush.
Fig. F10 Swinging arm bushes showing order of assembly
New bushes are pre sized and do not require reaming
after fitting. Assemble as follows:
4 Place the dust cover over the bush as in Fig. F10
and press the bush in fully.
5 Place the large ‘O’ ring in the dust plate.
6 Repeat for the second dust cover, bush and ‘O
ring.
7 Place the smaller ‘O’ rings in the bush recess of the
swinging arm. |
The swinging arm is now ready to refit to the motor-
cycle, using a new spindle if the original shows signs of
wear.
SECTION F9
REMOVING AND REPLACING FUEL TANK
Prior to removal of any fuel tank, remove the seat after
releasing the two large knurled securing knobs. This
will permit easier access to the rear tank fixings. Dis-
connect the fuel pipes from both fuel taps at the pipe
union nuts.
The various fixing methods used for glass fibre and steel
tarlks are shown in Fig. F11. Note specially the thick-
nesses and positions of the foam rubber support pads.
The front of the tank in all cases is of the stud and self-
locking nut variety. Roadster, Fastback and Interstate
types utilise rubbers of the washer type whereas all
other models use bonded rubber front mountings.
The rear of the tank prior to 1972 and excepting SS
and Hi-Rider models is secured by a single rubber band.
SS and Hi-Rider models use a resiliently padded steel
. Cross strap beneath the main frame tube to the rear of
the tank, secured by bolts and washers.
Existing glass fibre tanks continue with the same
fixings from 1972 but Roadster steel tanks and Inter-
state steel and glass fibre tanks utilise the rear cross
strap. To provide additional space and thus aid removal
on such models, removal of the side panels is desirable.
See illustrations Fig. F11
F —
_ Frame and Ancillaries F
Fig F11
Fuel tank fixings
o O &gt; CEO/
~~.
Frame and Ancillaries
SECTION F10
REMOVING AND REFITTING OIL TANK
Prior to draining the oil tank, take the motorcycle for a
short run to warm the oil which should then flow more
freely. Have available a receptacle of sufficient size to
receive the contents of the oil tank. Remove the seat
after releasing the large knurled side knobs.
Pre 1971 Roadster oil tank
Due to the lack of a drain plug the large hexagon oil
tank filter must be removed and the oil pipe union lifted
away to drain the oil. The position of the filter boss
makes it desirable to place a cardboard “chute” below
the boss, thus directing oil straight into the drain tray
and minimising mess. Proceed as follows :
1 Remove the oil-feed pipe nut and filter and drain
the tank.
Remove the fuel tank, carburetors and manifolds
EV&quot; as in Section F9 and E2.
- Dismantle the air filter and remove the element
(Section E10).
Disconnect the rear chain oiler pipe from the oil
tank. |
E Disconnect the crankcase breather from the oil
tank.
6 Detach the oil return pipe union from the tank.
7 Remove the two bolts and locking plate securing
the air filter backplate portion of the oil tank to the
battery carrier and collect the spacer.
8 Remove the nut, bolt and washer securing the oil
tank top bracket to the frame gusset. |
9 Remove the oil tank forwards, bottom end first.
10 Reassembly is a reversal of the removal procedure,
but if necessary use new oil sealing washers at
both sides of the oil pipe unions. If the motorcycle
is ready for service when the oil tank is refitted, fill
to the level indicated on the dipstick.
Pre 1971 Fastback oil tank
1 Remove the oil tank drain plug and drain the oil
into the receptacle previously obtained.
2 Remove the left side accessory cover by releasing
the Rotolok catch and lifting the cover off the rear
mounting pegs.
3 Part the rear chain oiler pipe by compressing the
spring clip and pulling the pipe clear of the felt
cartridge (in front of the battery).
4 Remove the oil tank breather pipe and air filter
breather pipe.
5 Remove the oil feed and return pipes from the oil
tank.
6 Remove the top front and top rear nuts securing
the tank to the flexible mountings.
7 Lift the oil tank upwards, clear of the bottom
rubber mounting and pull the bottom of the tank
out so that the filler cap clears the frame.
8 Reassembly is a reversal of the foregoing.
1971 and later models
&Agrave; common oil tank is used on all later models and the
following instructions apply to all editions.
1 Remove the two hexagon headed screws and
washers securing the right hand side panel.
2 Remove the drain plug and allow oil to drain into
the receptacle previously obtained.
3 Part the rear chain oiler pipe by compressing the
spring clip and pulling the pipe clear of the felt
cartridge.
4 Pull the crankcase breather pipe and oil tank
breather pipe away from the oil tank.
5 Remove the large hexagon headed oil tank filter at
the rear of the oil tank.
6 Pull off the oil return pipe from the stub at the rear
of the oil tank.
7 Remove the nut and washer securing the oil tank
to the top rear mounting.
‚8 Slacken only the nut on the top front flexible
mounting (the bracket is slotted and will then
slide clear).
9 Using an extension socket wrench, remove com-
pletely the bolt fitting through the bottom mounting
into the base of the oil tank.
10 Pull the bottom of the oil tank outwards so that the
filler neck clears the frame, slide the tank forwards
and outwards, lifting the bottom clear first.
11 Reassemble as a reversal of the foregoing. Take
care not to omit the spacer from the bottom mount-
ing rubber.
Frame and Ancillaries F
SECTION F11
L.H. ACCESSORY AND R.H. SIDE COVERS
The left hand accessory cover is retained by a Dzus
fastener at the top front of the cover. To remove, pull
and turn the ring of the fastener. The cover is then pulled
away from the frame at the front and lifted off the two
rear pegs. On all but certain Interpol models, the cover
can be lifted clear. On Interpol models with alternating
horns, the horn relays and control boxes are located
within the accessory cover and the cover cannot be
removed completely without disconnecting the horn
wiring.
Pre 1971 Fastback and Interpol models had no right
hand side cover, the oil tank itself being styled to match
the left cover. Roadster models and all 1971 and later
models have a right hand side cover secured at the top
by hexagon headed screws and washers, and supported
by an extension with rubber grommet at the bottom,
fitting inboard of the footrest support plate. Note that
the securing screws are both the same length on Fast-
back, Fastback L.R., Interpol and Interstate, but that the
rear screw is longer on other models.
SECTION F12
SHIMMING ENGINE MOUNTINGS
Prior to checking shimming note that whilst pre 1971
models can be supported on the centre stand during
this operation, 1971 and later models must be supported
by a stand or strong box placed below the main frame
tubes with the centre stand folded. This is necessary due
to the stand being mounted direct onto the engine plates
on later models. On such models the mountings would
be under tension with the centre stand in use. Proceed
as follows:
SECTION F13
CHECKING FRONT SHIMMING
1 Slide the left side gaiter back to give access to the
shims and plastic washer.
2 Push or lever the engine to the right until all slack
in the lsolastic mounting has been taken ug.
Holding the engine unit in this position, use feeler
gauges to measure the clearance between the
plastic washer and bright plated collar. (See
Fig. F12).
3 The ideal clearance is 0-010 in. (-25 mm). Make a
note of the actual clearance.
Fig. F12 Checking front mounting clearance
SECTION F14
CHECKING REAR SHIMMING
1 Slide the right side gaiter back to give access to
the shims and plastic washer.
2 Push the rear wheel to the left firmly and measure
the clearance between the plastic washer and
bright plated coliar.
3 The ideal clearance is 0-010 ix. (+25 mm).
SECTION 15
ADJUSTING FRONT SHIMMING
There are two methods of adjusting front shimming, the
quicker method (Method 1) deals with the mounting in
situ and is intended for checking as an item of routine
maintenance. Method 2 deals with removal of the
complete front mounting without removing the power
unit. This method is preferred where the mounting has
seen a great deal of service and requires a thorough
cleaning and the replacement of worn components.
Frame and Ancillaries
METHOD 1
1 Remove the self locking nut and plain washer from
the mounting bolt.
2 Align the flats on the hexagon of the mounting
bolt with the timing case casting of the engine.
3 Using a soft metal drift to avoid damaging the
threads drive the bolt through sufficiently that the
gaiter, spacer and plastic washer can be removed
together.
4 Remove the end cap and note the shim thick-
nesses.
Shims are available in 0-005 in., 0:010 in., 0-020 in.
and 0-030 in. thickness. If at the time of stripping, the
clearance was found to be, for example, 0-030 in.,
then a shim of 0-020 in. thickness should be added. It
is obviously more desirable to use one 0-020 in. shim
than a collection of shims to this thickness which tend to
deteriorate faster. Prior to reassembly, clean all the parts
including inside the gaiters, and grease lightly. Examine
the plastic washer for excessive wear producing
uneven thickness and replace if necessary. Proceed as
follows:
5 Reassemble the gaiter, spacing collar and shims
after attention, in the order shown in Fig. F14.
Note that the reassembly procedure is a reversal
of that used in dismantling but take care to fit the
cap with shims well over the actual mounting to
allow room for the gaiter, spacing washer and
plastic washer to be fitted together.
6 Secure the mounting bolt to a torque reading of
25 Ib./ft. (3-456 Kg/m).
METHOD 2
This operation involves removal of the complete front
mounting. In order to remove the mounting bolt com-
pletely, it may be necessary to remove the right exhaust
system as described in Section F19. Proceed as follows:
1 Remove the main mounting bolt nut and washer.
2 Using a soft metal drift drive the mounting bolt out
to the right side whilst supporting the weight of
the engine to prevent damage to the bolt threads.
3 Slide back the gaiter at the left side and remove the
collar, plastic washer and gaiter as a set.
4 Slide back the right hand gaiter and again remove
the parts.
5 Collect the end cap and shims from both sides.
6 Remove the two 3 in. studs securing the mounting
to the front of the crankcase and lift the mounting
away.
7 If the rubbers and buffers are to be changed in the
mounting, refer to Section F17.
At this stage clean the engine mounting, end caps and
spacing collars thoroughly to remove any corrosion, and
replace the plastic washers if this is obviously necessary
due to wear, uneven thickness or damage. Proceed as
follows:
8 Assemble the front mounting less shims in a plain
jawed vice. The order of assembly is shown in
Fig. F14 and the method of holding the mounting
in Fig. F13.
9 Fit and tighten down the mounting bolt washer
and nut. Note: Due to variations in thread length
on the bolt the nut may “bottom” on the threads.
If this occurs, add spacing washers to compensate
for the thickness of the main frame lugs. Secure
the self-locking nut to a torque setting of 25 ft./
Ibs. (3:45Kg/m) so that the spacing collars abut
to the centre spacer tube of the mounting.
10 Using feeler gauges, measure the clearance
between the end cap and plastic washer at one
side only.
If the measurement is found to be, for example,
0:050 in. then it will be necessary to add shims to a total
thickness of 0-040 in. This would best be achieved by
the insertion of a 0-020 in. shim at each side of the
mounting beneath the end cap. Having settled the
number and thickness of shims to add, remove the
mounting bolt, recheck that all parts are perfectly clean,
grease lightly using a silicone grease such as Releasil
No. 7, including inside each gaiter, and proceed as
follows :
11 Lift the gaiters, collars, etc. away from the mount-
ing to increase clearance during fitting.
12 Offer the mounting to the lower crankcase lug and
hold loosely in position with the bottom stud.
Frame and Ancillaries F
13 Pivot the mounting up to engage with the crank-
case lug and fit the top stud.
14 Secure both top and bottom stud nuts to 25 ft./Ibs.
(2:07 Kg/m) torque. |
15 Fit the right side cap shims, gaiter etc. first (the
order of assembly is shown in Fig. F14) and ensure
that the lip of the gaiter fits well over the mounting.
e
A
Fig. F13 Method 2. Holding front mounting in a vice for
checking.
16 Fit the main mounting bolt from the right side. It
will be necessary to align a flat on the hexagon
to pass the timing case and the bolt should pass
through until it is just flush with the left end of the
spacer tube.
17 Assemble the left end of the mounting — this is
facilitated by “peeling” the gaiter back and if
necessary by levering the power unit over in the
frame to the right.
18 Ensure that the gaiter lip is located properly over
the mounting, using a small screwdriver to assist
this operation.
19 Push the mounting bolt fully home, fit the washer
and nut and secure to 25 ft./Ibs. (3:456 Kg/m)
torque.
20 Although the assembly has previously been
shimmed and greased, ensure that both gaiter/end
cap assemblies can be revolved with finger pres-
sure. If this is not the case, recheck to ensure that
the gaiters have not been trapped.
SECTION F16
ADJUSTING REAR SHIMMING
Unlike the front mounting, the rear can only be dis-
mantled completely after stripping the primary trans-
mission as described in Section C13 and C14. The shims
can, however, be changed at the right side only with-
out the need for this further work. The normal method
of shimming, after the clearance has been checked |
following Section F14, is:
1 Remove the self-locking nut and washer from the
right end of the main mounting stud.
2 Using a soft metal drift drive the mounting stud
partially through, right to left until it protrudes
some 4 in. from the left hand side.
3 Slide the right gaiter lip off the mounting tube then
push down and rearwards clear of the frame the
gaiter, spacing collar and plastic washer as a
group.
4 Collect the right side shims and end cap. Examine
the plastic washer for excessive wear and replace
if necessary.
As with the front mounting, the thickness of shims
required should be determined from the measurement at -
the time of stripping as against the ideal clearance
0:010 in. (0-025 mm). For example, to correct a clear-
ance of 0:030 in., a single 0-020 in. shim would need to
be added. Reassemble as follows :
5 Clean and grease lightly the parts of the right end
cap/gaiter group, using a silicone grease such as
Releasil No. 7.
Pa am — &laquo;оон
Frame and Ancillaries
6 Fit .the shims and end cap to the mounting with
the thinest shim to the cap.
7 In order to refit the gaiter, plastic washer and
collar, the gaiter must be held back as far as
possible on the lip of the collar, as shown in Fig. F5
to gain sufficient room for fitting.
If it proves extremely difficult to insert the parts,
have a second operator push the rear wheel as far
as possible from right to left, thus providing maxi-
mum clearance at the end of the rear mounting.
8 After entering the end cap, gaiter etc. ensure that
the gaiter fits completely over the mounting and
cap without being trapped at either end. Check then
that the collar, plastic washer etc. are free to
revolve with the gaiter.
N
&gt;
ZA
|
&gt;
ENT
Service Tool (Drift)
Service Too! (Tapered Guide)
Rubber Bush &gt;
Front Isolastic Mounting Tube
9 Using a soft metal drift, tap the main mounting stud
right through from the left side and have the
assistance of a second operator to align the frame
lug with the mounting bolt, levering if necessary
between the engine plate and frame tube to aid
alignment, and inserting the spacer between the
alloy footrest mounting plate and frame bracket.
10 Fit the plain washer and self-locking nut and
tighten to a torque of 25 Ibs./ft.
After considerable usage it may be expected that the
mounting end groups have suffered wear and deteriora-
tion due to corrosion and after dismantling of the
primary transmission and removal of the mounting stud
the left end group can be removed for cleaning, greasing
and replacement of the worn parts. If the rubbers and
buffers are to receive attention as in Section F17 the
power unit must be removed from the frame as des-
cribed in Section F1. However, the need for attention
to these particular is comparatively rare.
nn
N
ZZ
Ya
N125
Fa 5 Using service too! 063971 to insert front isolastic rubber bushes
F
Frame and Ancillaries
Note: Later model Commandos have been fitted with
bronze-loaded PTFE plastic washers (brown in colour)
in place of the cream coloured polyurethane washers
fitted to earlier models. These washers resist wear and
deterioration; therefore, we recommend they be fitted
as replacements.
SECTION F17
RENEWAL OF RUBBERS AND BUFFERS
This section assumes that the end cap groups have
already been removed and that, in the case of the rear
mounting, the power unit complete has been removed
to gain access.
Renewing Isolastic Mounting Rubbers
Pre 1970 models not covered by this manual used
mounting bushes with outer steel sleeves which often
proved extremely difficult to remove. 1970 and later
models use bonded mounting bushes which are lubrica-
ted at the time of assembly and which present no such
ARNOT m=
99
Fig F15
problems. Removal does not necessitate the use of
special tools though reassembly requires the use of
special tool 063971. Proceed to remove as below but
refer to Fig. F14 for the positions ot bushes and buffers.
Front mounting
1 Place a suitable sized bar into the steel centre of
either bonded bush only sufficiently to occupy the
bush sleeve. Apply strong side pressure on the bar
and the bush will turn in the mounting tube and
can be prised out.
2 Lift out the spacer tube complete with two rubber
buffers.
3 Repeat the operation of removal by side pressure
applied by a bar through the remaining bush.
Examine all parts for deterioration and renew parts
as necessary before reassembly.
Isolastic mountings exploded view
hm LE a
Frame and Ancillaries
10
Fit the tapered guide body 063971 over the end of
the mounting tube as shown in Fig. F15.
Take the first bush and paint the edge with a
rubber lubricant.
Press the bush either way round into the tapered
guide to compress the rubber to the diameter of
the mounting tube.
Using service tool 063971 as in Fig. F15, either
press or drive with a hammer so that the bush
slides home into the mounting tube and the
shoulder of this tool abuts to the top of the tapered
guide. The first bush is now in the correct position.
Now invert the mounting and slide the two buffer
rubbers over the spacer tube until they are central,
with a gap of $ inch (12:70 mm) between the
buffers.
Place the spacer tube complete with buffers in the
mounting tube, resting on the first bush fitted.
Repeat operations 4, 5, 6, 7, for the second bush.
The front mounting is now complete with rubbers
and ready for reassembly.
=? Place a suitable sized bar into the steel centre of
either bonded bush only sufficiently to occupy the
bush sleeve. Apply strong side pressure on the bar
and the bush will turn and can be prised out.
Lift out the first short spacer tube complete with
buffer.
Remove the centre bush. Since this is recessed far
into the mounting tube, access by a bar as for the
“end bushes will be more difficult. An alternative is
to use the bar as a drift, then strike one side of the
bush on the rubber portion and the bush will turn
sideways in the tube. The bush may then be pulled
easily from the mounting tube.
Collect the second spacer complete with buffer.
Repeat the operation of removal by side pressure
applied by a bar through the remaining bush.
Examine all parts for deterioration and renew as
necessary before reassembly.
Paint the edge of the centre bush with rubber
lubricant (all the rear mountain bushes are identical
but of smaller outside diameter than the front
mounting bushes).
7 By hand pressure only and without the need for a
tapered guide, push the centre bush into the end of
the mounting tube. Then using a suitable length of
large diameter tubing push the bush into the
centre of the tube 3% inches (75-15 mm) from each
end of the tube.
8 Place one spacer tube, with buffer rubber centrally
positioned, against the centre bush.
9 On the same side of the mounting, lubricate and
press in the second bush until it abuts to the spacer
tube.
10 Invert the mounting tube and repeat operations
8 and 9 for the second side of the mounting.
The rear mounting is now complete with rubbers
and ready for reassembly.
Fig. F15. Front mounting assembly tools. “A” shows
bush in tapered guide. “B&quot;” shows bush entered in
mounting tube.
SECTION F18
REAR FENDER
Removal and refitting of the rear fender is similar for all
models excepting Fastback on which there is the addi-
tional problem of the tail section fairing. The separate
routines are given below:
Fastback:
1 Release the two large knurled knobs securing the
seat and lift the seat straight up and clear of the
frame.
2 Remove the suspension unit top bolts to release
the forward ends of the tail section.
3 Remove the clip from beneath which secures the
tail section to the rear frame loop.
4 Disconnect the tail lamp leads and direction
indicator leads where used at the snap connector
terminals inside the tail section.
5 Remove the nuts and washers at the bottom front
and lift the fender away.
F |
Frame and Ancillaries
6 Reassembly is a reversal of the foregoing but do
not omit to reconnect the tail lamp leads. Where
direction indicators are fitted, ensure that they
work correctly when reconnected.
Roadster:
1 Release the two large knurled knobs securing the
seat and lift the seat straight up and clear of the
frame.
2 Release the tail lamp with fairing and number plate
support as a group, by removal of six bolts and
plain washers.
3 Disconnect the tail lamp leads (and the direction
indicator leads where fitted) and lift away the tail
lamp and tail lamp fairing group.
4 Remove the bottom front two self-locking nuts and
plain washers securing the rear fender to the
bracket from the frame gusset.
5 Reassembly is a reversal of the foregoing but do
not omit to reconnect the tail lamp leads. Where
direction indicators are fitted, ensure that they
work correctly when reconnected.
SECTION F19
EXHAUST SYSTEM
The dismantling and reassembly routine for 750
Commando models with the various low level exhaust
systems is similar but the high level system of the “S”
model, upswept to the left side requires a different
technique. The downswept exhaust systems are shown
in Fig. F16 and the “S&quot; type system in Fig. F17.
Removing and Refitting — all 750 models except
““S&quot; type:
1 On late models with exhaust lockring tab washers,
flatten back the tabs.
2 Using service tool 063968 unscrew the finned
exhaust lockrings and allow these to hang on the
exhaust pipes.
3 Remove the nuts securing the muffler (silencer)
mounting plates to the rubber mountings, so that
at the next stage the mufflers are removed with
plate attached.
4 Lift each exhaust system clear.
5 When assembling the exhaust system, fit the
copper/asbestos sealing ring into the exhaust port,
offer the exhaust pipe to the port and, holding in
the correct position, tighten the lockring suffi-
ciently to hold the exhaust pipe in the correct
position whilst permitting it to be rotated slightly.
Now assemble the muffler to the exhaust pipe and
to the muffler mountings.
6 Tighten completely the muffler mountings, for-
ward clip and lockring.
When refitting the exhaust system, if the exhaust system
Is not assembled correctly to the frame, it can lie in the
wrong plane.The tendency is to push the system to its
lowest position during fitting so that the centre stand
and other equipment can come into contact with the
exhaust pipe and mufflers. Assembly as above will
prevent both misalignment and strain on any of the
fittings.
Removing and Refitting “S” type Exhaust:
1 Using service tool 063968 unscrew the finned
exhaust lockrings and allow to remain loosely in
place.
2 Remove nut from rubber mount block on bracket
adjacent to suspension unit.
3 Lift off pipe and muffler complete.
4 Repeat for other pipe and muffler.
5 On reassembly, the use of new type tabbed
washers to secure the lockrings is recommended.
Frame and Ancillaries
Fig. F16 750 Low level exhaust systems
Frame and Ancillaries
=
“S$” type exhaust
Fig. F18
Frame and Ancillaries F
SECTION F20
&copy;) 850 EXHAUST SYSTEMS
1 Fit L.H. exhaust pipe complete with lockring,
sealing and tab washers. Run up lockring but do
not tighten at this stage.
2 Fit L.H. muffler to exhaust pipe, align the mounting
pommels and assemble loosely to the L.H.
muffler bracket mounting rubbers.
3 Fit R.H. exhaust pipe complete with lockring
sealing and tab washers. Run up lockring but do
not tighten.
4 Fit R.H. muffler to exhaust pipe, align the mounting _
pommels and assemble loosely to the R.H.
muffler bracket mounting rubbers.
D Slide both connector sleeves to the centre of the
cross tube. Place cross tube in position and slide
both connector sleeves outwards to engage with
the exhaust pipe stubs.
6 Slacken off all footpeg support and muffler
bracket bolts in the left and right hand aluminium
support plate castings —to allow the brackets to
swivel and adjust to the exhaust pipe/muffler
alignment.
Tighten up the total exhaust system, commencing
at the cylinder head lockrings and cross tube
connector sleeves. Do not forget to bend up the
lockring tab washers.
8 Finally retighten the muffler bracket/support plate
Fig. F18 850 exhaust system bolts.
——
Front
Forks/Steering
Front Forks
and
Steering
Front Forks/Steering
AT REST (STATIC) COMPRESSING C1
Valve lifted as far as
—— peg permitting oil to
pass cutaway seat washer
[EL te a TT ES
[ETE
NOTE: All forks shown
less main spring
OIL UNDER
LOAD
ГИ 12s
Fig. G2 Fork at rest, compressing, extending, and almost fully extended
- Front Forks/Steering С.
FINAL COMPRESSION C2 EXTENDING
Oil forced out
— of damper between
rod and body
Valve closed onto seat
preventing oil passage
Oil trapped between
bushes forced back
through big hole then
small hole into stanchion
as big hole becomes
blanked off
Valve still lifted and oil
passing to top half of
damper body
—— As stanchion passes
over damper tube taper, oil E
passage progressively He
restricted to slow down fork 3
action and finally provide
hydraulic bump stop
Oil sucked into
~ damper body:
Front Forks/Steering
SECTION G1
FRONT FORK DESCRIPTION
The Commando Fork is a development of the “Road-
holder” Fork which is world famous as an extremely
strong and precise steering unit under all conditions.
The forks comprise high quality seamless chrome steel
main tubes with light aluminium sliding members for
reduced unsprung weight. Fork movement is controlled
by long single rate springs and two-way oil damping.
The sliding members are supported on oil impregnated
sintered bronze bushes at the top and steel at the bottom
to give maximum support and to minimise wear. The
fork yokes are substantial cast components which
provide great rigidity. The steering head pivot com-
prises two pre-packed and sealed ball journal bearings.
The steering head arrangement illustrated is that used on
1971 and later models with the stem captive in the upper
yoke and incorporating non-adjustable bearings.
SECTION G2
HOW FORK WORKS
Consider that as the front wheel meets a bump in the
road surface the front forks are compressed against the
main springs. As the wheel passes the bump the forks
= E are permitted to return to the static position. Should
=&quot; the motor-cycle become “front end light” such as
negotiating a hump-backed bridge, the fork extends
fully but once again on level road, returns to the static
position. The natural &laquo;tendency for a spring controlled
suspension system is to over react and oscillate before
returning to static position. Such a system would
result in a pitching motion on rough roads and a
subsequent loss of stability. To counter this condition,
oil damping is provided which in the case of
the Commando fork slows down the spring return
both on compression and extension. Each fork
slider contains 150 cc of oil which is metered by a rod
and valve damper assembly. The damping sequence is
detailed in the following text and the complete fork
assembly is shown in Fig. G5. In the latter diagram “A”
illustrates the fork at rest with parts descriptions, В” {Пе
form compressing and “C1” and “C2” the fork extend-
ing.
+
a
&quot;№
FORK AT REST (A)
The oil lies in the bottom of the slider and occupies the
spaces between top and bottom bushes, damper tube
and main tube and occupies the lower end of the damper
tube.
FORK COMPRESSES (B)
Consider that the main tube and damper rod remains
stationary thus as the fork compresses, the slider and
damper tube rise. As the slider rises, oil passes into the
lower end of the damper tube. There is no passage of oil
between the damper rod and damper tube cap but oil
passes from the slider through the main tube bleed holes
between the bushes. The vacuum caused between the
fork bushes during compression causes oil to be sucked
from the space between the fork bushes. As the fork
compresses further, the damper tube passes further into
the main tube until the cone shaped bottom area enters
and the oil passage into the main tube is progressively
cut off until only the bleed hole into the damper tube
remains. Oil is then able to pass through the bleed hole
slowly, thus slowing or “damping” the fork action,
finally providing a hydraulic bump stop-on full com-
pression.
FORK EXTENDING (C1 and C2)
The main tube remains stationary whilst the slider and
damper tube descend. Oil remains trapped between the
top and bottom bushes. The damper valve within the
damper tube remains closed thus as the damper tube
descends, oil passes between the damper rod and
damper tube cap into the space between the damper
tube and main fork tube. As the fork continues to extend,
oil trapped between the fork bushes is forced back into
the slider through the large hole then the small hole to
slow down the fork action and prevent the fork “top-
ping” heavily.
Front Forks/Steering
SECTION G3
REMOVAL OF FRONT FORKS
x
Removal of the front forks is most easily achieved by
dismantling in parts rather than attempting to remove
the fork assembly complete. Pre 1971 models had the
steering stem captive in the lower yoke whereas 1971
and later models have the stem captive in the upper
yoke. This alters the dismantling procedure for the
yokes. In the case of disc braked models, it will be found
easiest to remove the hydraulic system as an assembly,
thus relieving the necessity for refilling and bleeding the
system. Release the hydraulic pipe bracket from the
right fork slider at the fender bridge. Remove the two
boits and spring washers securing the caliper to the
slider and lift the caliper away, complete with pads and
still attached to the brake hose. At this stage if the brake Fig. G3 Hydraulic system removed complete—note spacer
between brake pads
&quot; lever is operated accidentally, the pads and pistons will
be forced from the caliper and the fluid lost. To protect
against this, place a spacer between the brake pads — a
suitable piece of clean wood or preferably a piece of
plastic tubing would be ideal. Remove the four cross-
headed screws securing the master cylinder to the right
switch cluster, hold the master cylinder but allow the
switch cluster to hang on its leads. Pull back the plastic
3 Lift clear the speedometer and tachometer in their
cases and allow them to hang on the cables.
switch cover from the master cylinder and disconnect
both Lucar terminals. Release the large spring clips
securing the hydraulic hose to the right fork leg and lift
the complete hydraulic system away. The system is 0
sealed and can therefore be laid down until it is to be 4 Slacken the lower lug socket headed pinch Sores 1]
refitted see Fig. G3. Support the motorcycle by using a (see Fig. G8). SET
box or block of wood beneath the lower frame rails and &copy; |
proceed as follows:
The fork main tubes are a tapered fit into the upper
yoke and require a shock to free them. The shock may
be delivered by grasping the fork slider with both hands
1 Remove the front wheel (see Section H5 for disc
brake wheel or Section H8 for drum braked
wheel).
and snatching downwards several times. If this fails to
break the taper, replace the chrome top bolt at least six
threads without the instrument case and using a block
2 Unscrew and lift the fork tube large chrome top of wood to protect the chrome finish (see Fig. G4)
bolts and using two spanners as shown in Fig. G7 deliver several blows with a hammer. This will release
release the damper rod from each top bolt. the main tube from the upper yoke.
Front Forks/Steering
Fig. G4
Shocking main tubes free of upper yoke
A
5 Remove the first fork leg, replacing the top bolt to
prevent oil loss.
у
6 Repeat the operation for the second leg.
Note that the steering head bearings are of the sealed
ball journal type which will not be disturbed by removal
of the yokes and stem.
7 1971 and later models. Remove the lower yoke.
This is accomplished by releasing the tab washer
and removing the large nut from the bottom of the
fork stem. Support the headlamp and tap the lower
yoke downwards clear of the stem.
E
8 Collect the two bottom and one top “O' ring
released by each headlamp bracket and top cover
and allow the headlamp to hang down on its
harness, with fork covers attached.
9 The upper yoke is now captive only by the tightness
of the stem in the steering head bearings. Use a
hide mallet or soft drift to drive the stem up through
the bearings, allowing the upper yoke to be
removed. Collect the dust cover and washer.
7A Pre 1971 models. Remove the large chrome blind
nut and washer and drive the upper yoke up off
the stem.
8A Remove the nut and dust cover from the stem.
9A Using a hide hammer or soft drift, drive the stem
down through the bearings, to release the lower
yoke and stem.
\
Note: 850 models use a special pair of fork yokes
identified by “ANG” stamped on lower surfaces of both
yokes. These yokes must be used for 850's and must
not, under any circumstances, be interchanged with
earlier types.
Assembly is identical with later 750 design as
outlined above.
_ Front Forks/Steering
SECTION G4
DISMANTLING FORK LEG
Removal of the fork leg assemblies is described in
Section G3. Pour oil, from the fork leg to be dis-
mantied, into a suitable receptacle and proceed as
follows :
1 Secure the bottom of the slider in a plain jawed
vice, with the leg vertical.
2 Lift the plastic gaiter up the main fork tube.
— 3 Remove the threaded collar by hand pressure only,
or, if necessary, by the use of strap wrench 064622
which will not damage the finish.
4 Grasp the main fork tube in both hands and with a
number of upward jerking movements, free the oil
seal, paper washer and top collar. -
5 Lift the main tube away from the slider.
6 Remove the damper tube anchor bolt (the various
components are shown in Fig. G5) and collect
the thick washer. |
7 Lift the main spring and damper tube attach&eacute;d,
clear of the slider. .
— 8 Collect the bottom fibre washer from the damper
tube for re-use. |
9 Remove the slider from the vice, secure the damper
tube carefully in the vice, taking care not to crush
it.
10 Unscrew and lift away the alloy damper tube cap.
11 Withdraw the damper rod.
12 Grip the rod in a vice and remove the damper rod
locknut, collecting the squared washer and
damper valve.
13 The damper valve stop pin is free to be removed.
41 Removal of the square section circlip at the bottom
of each fork tube permits removal of the steel bush.
AEE
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Fig. G5 Front fork exploded view
Front Forks/Steering
SECTION G5 3 At the peg end of the damper rod assemble the
damper valve, lip end down (when in the vice)
REASSEMBLING FORK LEG followed by the squared washer and nut which
must be tightened securely.
Prior to reassembly, wash all parts very thoroughly in
gasoline (petrol) and allow to dry. Examine for wear on 4 Assemble the damper rod to the damper tube then
the fork bushes and main tube. Check that the damper fit and secure the damper tube alloy cap.
valve and stop pin are undamaged and that the damper
rod is not bent. When all parts are sound, proceed to
reassemble as follows: 5 Place the spring over the damper rod and secure
with the thick washer and nut.
7 Smear the main tube with clean oil then enter it
into the slider.
AL) a
Хо
+. BRAKE PIPE
Las,
“Y; Er Par Pa
, к . X &copy;... 6 Place the fibre washer over the end of the damper
HYDRAULIC HOSE 37286 A tube and offer the damper tube assembled, to the
) E AN E slider, securing with the thick washer and bolt.
7 a x a
( &ntilde;o \ N \ \
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+
Tom
8 Fit the top bush, paper washer and oil seal : the oil
seal will need to be tapped home using a suitable
tubular drift.
9 Fit the threaded collar and tighten down.
10 Refit the plastic gaiter.
The fork leg is now ready to refit as described in
Section G8.
Fig. G6 Hydraulic system fittings to fork leg
If the lower bush on the main tube has been
removed, fit a new bush and refitghe circlip ensur-
ing that it is bedded well all round.
—
2 Grip the damper rod in a vice and fit the damper
valve stop pin. The order of assembly is shown in
Fig. GD. Fig. G7 Releasing damper rod from fork top bolts.
- Front Forks/Steering
SECTION G6
RENEWING STEERING HEAD BEARINGS
1971 and later models utilise sealed non adjustable
ball journal bearings with a spacer tube to prevent the
bearings being forced into the frame head tube. On such
models, after removal of the forks as in Section G3, the
bearing spacer tube must be pushed to one side so that
a drift can be applied to the inner race of the bottom
bearing and the bearing driven out with care. The bear-
ing spacer will be released at the same time. By using
the drift from the other end of the steering tube the
second bearing can then be driven out.
To replace the bearings, fit the bottom bearing fully
home into the housing absolutely square. Use a should -
ered drift through the bearing to hold it in line with the
housing whilst abutting against the outer race. Place the
spacer tube loosely in position and drive the top bearing
in to abut to the spacer tube.
As the fork yokes are assembled the bearings will be
pulled up to the spacer tube.
1970 models used adjustable sealed ball journal
bearings and these had no spacer tube. Removal and
reassembly is similar to the sequence used on later
models except that both bearings must be fitted up to
the abutments within the steering head tube prior to
assembly of the steering yokes.
SECTION G7
STEERING HEAD ADJUSTMENT
1971 and later models — The steering head bearing
arrangement, where the bearings abut to a centre spacer
tube, is non-adjustable. The stem nut fitted from beneath
the lower yoke has a tab washer to prevent slackening.
G
Pre 1971 models — The steering head bearings take
the form of ball journal bearings but are adjustable when
necessary. If there is play in the steering head bearings
the movement which takes place when traversing rough
roads or when the front brake is applied will damage the
bearings. To check the adjustment, support the motor-
cycle under the crankcase with the front wheel clear of
the ground. Stand astride the front wheel, grasp the
fork legs and attempt to move them backwards and for-
wards against the steering head races. Movement will
most easily be detected by holding the fingers at the
joint between the fork and steering head tube whilst
checking.
Adjusting Pre 1971 Steering Head Bearings
1 Slacken top nut (A) in Fig. G8 (this is facilitated
by removing the handlebar).
NY
Release fixing nuts (B) to allow the fork tubes to
slide in the yoke.
3 Using a Service Tool 060942, tighten adjusting
nut (C) a little at a time to take up play. Continue
to adjust until the forks turn freely from lock to
lock without binding. |
4 When adjustment is correct, tighten nut (A),
clamping nuts (B) and refit the handlebars.
Fig. G8
Steering head adjustment—pre 1971
G
Front Forks/Steering
SECTION G8 1970 Models
1A Pass the stem of the bottom yoke up through the
REFITTING FRONT FORKS bearings.
Reassembly of the front forks is virtually a reversal of the
dismantling procedure though for clarity, the full
procedure is detailed below :
2A Place the top bearing dust cover over the stem.
3A Fit the fork stem nut and tighten down to pull the
stem fully home through the bearings. Since the
bearings are adjustable, tighten the nut to
eliminate any shake between the stem and steering
head but not sufficient for the bearings to bind as
the yokes are turned lock to lock.
1971 I del 4A On Fastback models only, place both top shrouds
and later models with headlamp brackets loosely in position, com-
plete with top rubbers.
1 Place the top dust cover and washer over the top DA Place the top yoke over the stem and loose
steering head bearing. Note that the washer fits assemble with the large stem washer and large
below the cover. blind chrome stem nut.
6A Before proceeding to operation 6 “All Com-
2 Pass the stem of the upper yoke through the mando,” ensure that the assembled spring cover
bearings. This will almost certainly require the use tubes are in position.
of a block of wood and a hammer to tap the stem
fully home.
All Commando models _
3 Lift the headlamp and top covers roughly into 6 Offer both fork legs through the lower and upper
position, place the single ‘O’ ring in each side of
the upper yoke to locate the tops of the fork covers
Use heavy grease to hold the ‘O”’ rings in place.
Place the lower yoke, with two ‘O’ rings to locate
each fork cover, over the steering stem. Fit the tab
washer and nut to the stem and commence to
tighten. As the lower yoke is raised, locate the top
covers, both top and bottom.
Tighten the nut sufficiently to pull the lower yoke
into position, but do not secure fully yet.
yoke and pull the main tube tapers into the upper
yoke using the instrument cases and large chrome
top bolts.
With the fork legs secured by the top bolts, snug
the socket headed pinch screws.
Now tighten the fork securing points shown in
Fig G8/9 in this sequence : Chrome top bolts, main
fork stem nut, lower yoke pinch screws. Note that
the stem nut must not be over-tightened. On 1970
models this would damage the steering head
bearings, which must adjust until the forks are free
to turn with no perceptible play.
_ Front Forks/Steering G
10
—
11
12
13
— 14
On 1971 and later models, tighten the stem nut to
15 1b/ft (207 kg/m) and tap over the stem nut tab
washer.
Again lift the large chrome top bolts, firstly to add
oil and secondly to connect the damper rods.
Measure the required quantity of oil for each fork
leg (150 cc of SAE 20). Pouring the oil into the leg
will prove a long operation. To speed up the filling
operation, pour in as much of the measured
quantity as possible, place the hand firmiy over
the top of the main tube and extend the fork leg.
Do this several times to speed up oil! drainage into
the slider. When the measured quantity has been
added, and with the instrument case held in posi-
tion, connect the damper rod to the chrome bolt as
in Fig. G7. Using a socket wrench on the chrome
bolts, tighten to 40 Ibs/ft (5.83 kg/m).
Disc Brake Models. Secure the master cylinder
to the right switch cluster with the four long
screws.
Disc Brake Models. Bolt the caliper assembly to
the right fork slider using two bolts and washers
tightened to a torque setting of 25 ft/lbs (3.45
kg/m). Fit the hydraulic hose bracket over the studs
on the right slider.
Fit the front fender, securing with four plain
washers and nuts at the bridge stay and one bolt
and plain washer at the fork end of each stay.
Refit the front wheel as in Section H6 or H8.
15 Disc Brake Models. Clip the hydraulic hose to
the right fork top cover (two spring clips), feed the
front brake stop switch leads through the stop
switch cover one at a time and connect the Lucas
terminals at the stop switch.
On disc brake models, it is vital to “pump” the front
brake lever several times after the wheel has been
removed to restore brake pressure before the brake is
Fig. G9 Showing stem nut tab washer locked to nut
_ Brakes, Wheels and Tires H
Brakes
Wheels
and
Tires
_ Brakes, Wheels and Tires H
SECTION H1 3
REMOVING REAR WHEEL
(Without disturbing the brake and sprocket).
Two types of rear wheel have been used, the one used
prior to 1971 having the rear wheel brake drum and
sprocket bolted up to the hub and the 1971 and later
type having polyurethane shock absorber segments let
into the hub and steel paddles fitted to the rear brake
drum engaging in the polyurethane segments. This
arrangement permits the wheel and brake drum to be
separated merely by removal of the rear axle.
To remove either type of wheel, the motorcycle must
be supported with the rear wheel clear of the ground.
—
Fig. HT Rear wheel removal post—1971 1
2
3
1971 and later models — See Fig. H1.
4
1 Unscrew the wheel axle “B” at the right hand side
and withdraw.
5
2 Remove the spacer “C” and speedometer drive
| gearbox “D” which are loose after the axle is with-
— drawn.
Fig. H2
Separate the wheel from the brake drum. If the
wheel is difficult to remove, use a lever between
the wheel and brake drums to separate the three
paddles from the shock absorber segments in the
hub.
Rear wheel removal pre- 1971
Pre 1971 models — See Fig. H2.
Disconnect the speedometer drive cable.
Remove the rubber plugs which give access to the
rear wheel sleeve nuts.
Remove the rear wheel sleeve nuts.
Withdraw the wheel spindle from the right hand
side.
Collect the spacer and speedometer drive
gearbox which are released as the axle is
withdrawn. If the wheel is difficult to remove, use
a lever between the wheel hub and brake drum.
Brakes, Wheels and Tires H
SECTION H2
REFITTING OF REAR WHEEL
1971 and later models
Re-assembly is virtually a reversal of the removal
procedure, but the following observations are made :
1
Fig. H3
Fit the wheel to the paddles, engaging the paddles
between the drive and rebound segments in the
hub.
Fit the speedometer gearbox, exercising care to
engage the two drive dogs with the slots in the
hub bearing locking ring.
Position the dull plated spacer, then slide the wheel
axle complete with washer into position and
tighten fully.
Paddles and shock absorbing pads
Previous models
&gt;
Turn the brake drum so that one of the three studs
is approximately in line with the swinging arm
tubes and so facilitate passing the bearing boss on
the hub past-the other two studs.
Fit the wheel to the studs.
Fit and tighten the sleeve nuts.
Replace the rubber plugs.
Fit the speedometer drive gearbox, exercise care to
engage the two drive dogs with the two stots in
the hub bearing locking ring.
Position the dull plated spacer then engage the
wheel axle complete with washer and tighten
fully.
SECTION H3
COMPLETE REAR WHEEL REMOVAL
In order to remove the wheel complete, support the
motorcycle on the centre stand and proceed as
follows: |
1
2
Disconnect the rear chain at the split link.
Disconnect the leads from the stop lamp switch.
Disconnect the rear brake cable rod by removing
the adjuster nut (see Fig. H4) and pulling the rod
through the brake expander lever roller.
Disconnect the speedometer cable from the drive
box.
Slacken and remove the main wheel axle from the
right side.
Remove the right side spacer, washer and speedo-
meter drive box. .
Remove the left side axle nut.
Pull the wheel over to the right side so that the
brake plate stop peg and the dummy axle in the
brake drum clear the slots in the swinging arm.
The wheel can now be lifted clear.
Brakes, Wheels and Tires H
* _ZZAN LL
BRAKE CAM GREASE /__—=)
NIPPLE
“Tore A
\ V &gt;
HY
{WHEEL SPINDLE REAR BRAKE
A NUJIAR y ADJUSTER Y
Rear wheel features
Fig. H4
Dismantling
Before dealing with the axle and bearings, separate the
brake assembly from the brake drum, then the brake
drum from the wheel hub.
1971 and later models utilise shock absorber pads of
polyurethane in the hub into which the shock absorber
paddles on the brake drum fit. Therefore, on 1971 and
later models, the hub can be lifted away from the brake
drum without further dismantling. |
“On pre 1971 models, remove the three blanking plugs
from the hub disc and, using a socket wrench, remove
the three sleeve nuts securing the hub to the brake drum
and separate these items. Lift the brake plate complete
with shoes away from the brake drum.
SECTION H4
REAR HUB DISMANTLING
In order to change the wheel bearings, remove the wheel
complete as described in Section H3. In the case of
pre 1971 rear wheels without shock absorber, the wheel
should be parted from the brake drum by removal of
three extended nuts from the right hand side. On this
type of wheel, illustrated in Fig. HS there is no bearing
in the brake drum. The wheel fitted to 1971 and later
models should be removed complete as described in
Section H3. With the wheel axle removed, separate the
brake drum from the wheel hub — the “paddles” on the
brake drum are merely a push in fit between the
polyurethane shock absorber segments. On the 1971
type, a double row ball journal bearing is fitted to the
rear brake drum. The bearing arrangement differs
between 1971 and earlier models in the wheels, as will
be seen from Fig. H6, the later wheel containing an
additional double row bearing in the brake drum but a
pair of single row bearings in the wheel hub.
Pre 1971 models — See Fig. H5.
To dismantle this type of rear hub proceed as follows :
1 At the speedometer drive box side of the wheel
unscrew the LEFT HAND THREAD lockring using
peg spanner tool, 063965 and remove.
Fig. H5 1970 type rear wheel exploded
Brakes, Wheels and Tires H _
Take out the distance piece and felt washer.
Take the rear axle with thick washer and fit over it
the large plated spacer which fits between the
speedometer drive box and fork end.
Insert the axle with washer and spacer through the
double row ball journal bearing from the brake
drum side of the hub (the brake drum has
previously been removed).
Г
EJ
Using a hide hammer or mallet, drive on the end of
the axle until a stop is felt. Driving will have moved
the double row bearing further into the hub, mov-
ing the bearing spacer tube and in turn, starting to
drive the lockring side bearing out of the hub tube.
When the stop is felt, the double row bearing has
come up against a shoulder in the hub.
Remove the rear axle and spacer and insert the
front wheel axle, threaded end first from the brake
drum side. Hold square and tap gently with a hide
_ Brakes, Wheels and Tires H
A
o)
hammer to drive on the bearing spacer and dis-
place the speedometer drive box side bearing and
spacer completely from the hub.
7 Remove the front wheel axle and re-insert the rear
axle and large plated spacer from the lockring end.
8 Hold central in the brake drum side bearing (the
double row bearing) and drive out the bearing
complete with felt retaining washer, felt seal and
dished washer.
1971 and later models — See Fig. H6.
With the exception that the later rear hub has two single
row ball journal bearings in the hub, rather than a single
row bearing at the lockring (speedometer) side and a
double row bearing at the brake drum side, the dis-
mantling and reassembly details are the same as for the
previous wheel. Later models incorporate shock absorber
segments in the hub and to ensure rigidity of the wheel
a double row bearing is incorporated in the brake drum
itself. The brake drum bearing is dealt with separately.
SECTION HS5
REAR HUB REASSEMBLY
Prior to reasembly, clean and inspect the bearings, felt
seal and seal retainers for roughness, wear, damage or
corrosion and make replacements as necessary. Proceed
as follows:
Pre 1971 models
1 Pack bearings with the recommended grade of
grease (see Section K1).
2 Fit the single row bearing into the threaded (lock-
ring) side of the hub, sufficiently to allow the
lockring to be fitted.
3 Fit the felt seal and locking ring and tighten.
Remember that the lockring is LEFT HAND
threaded. Tighten with peg spanner tool 063965.
If the peg spanner is not available, take special care
not to damage the slots which drive the speedo-
meter drive box.
4 Fit the bearing spacer tube. On pre 1971 models
which have a double row bearing at the brake side
and a single row bearing at the speedometer drive
box side, the bearing spacer has unequal length
ends and the long end locates to the single row
bearing. &copy;
5 Press the brake drum side bearing (on pre 1971
models a double row and on 1971 and later
models, a single row bearing) squarely into posi-
tion in the hub and drive home applying load only
to the outer race. Load on the centre race can
cause damage.
6 Fit the felt retaining washer, felt seal and dished
washer and on pre 1971 models, lightly peen the
dished washer into position. 1971 and later
models use a push in. washer.
The brake drum and sprocket contain the dummy axle
and, in the case of 1971 and later models, the double
row bearing and sealing felt. The bearing can be
removed and refitted to the later brake drum and
sprocket as detailed below.
1971 and later models
The later type of rear wheel incorporating a shock
absorber is supported by two single row bearings in the
hub and a double row bearing in the brake drum. The
brake and brake drum are separated from the swinging
fork as detailed in Section H3. To remove and replace
the double row bearing and seals, proceed as follows :
1 Lift the brake assembly away from the drum
2 Remove the bearing spacer (the shouldered spacer
protruding from the centre of the bearing towards
the wheel). This will be a relatively tight fit into the
bearing and may need to be gripped in a vice whilst
the brake drum is tapped carefully away from it.
3 Prise out the lipped washer covering the felt seal.
Wei rie mm ee
rm EEE
Brakes, Wheels and Tires H _
10
11
12
13
Collect the felt seal and felt retaining washer.
Using circlip pliers, remove the large bearing retain -
ing circlip.
Using a hide hammer or mallet, drive the threaded
end of the dummy axle. This should pass into the
brake drum, displacing the inner felt seal and
retainers and driving the double row bearing clear.
Clean, inspect and replace as necessary the bearing,
seals and retainers. Check that the shock absorber
“paddles” are secure in the brake drum.
Pack the bearing with the recommended grade of
grease (see Section K1).
Fit the inner washers to the brake drum, holding in
place by inserting the dummy axle, threaded end
through towards the brake side.
Using a suitable shouldered drift against the edge
of the outer race, drive the double row bearing
squarely into the brake drum.
Fit the bearing retainer circlip, sharp edge out-
wards, and ensure that it is bedded all the way
round the groove. Failure to observe this pre-
caution can permit free lateral movement of the
brake drum and sprocket.
Fit the inner felt retaining washer and felt seal.
Fit the outer lipped felt seal retainer.
The brake drum is now reassembled ready for fitting to
the motorcycle.
SECTION H6
REMOVING AND REFITTING FRONT WHEEL
(Disc Type)
Removal
Support the motorcycle with the front wheel clear of the
ground. The brake assembly remains undisturbed since
only the disc is removed with the wheel. Proceed as
foilows :
1
Slacken the fork end clamping nut. (See Fig. H7).
Fig. H7 Disc brake front wheel removal
Taking the weight of the front wheel in one hand
withdraw the axle using a tommy bar. It will be
found that the wheel can be removed most easily
by withdrawing it forwards to disengage the disc
from the pads.
To prevent the brake pads being ejected by
unintentional application of the brake with the
wheel removed, place a clean ; in. (6-7 mm)
spacer of wood, metal or plastic between the pads.
Collect the wheel bearing dust covers to prevent
loss. (See Fig. H8).
Fig. H8 Disc brake wheel
_ Brakes, Wheels and Tires H
Refitting
5
Offer the wheel with both dust covers in position
and, with care, guide the disc between the brake
pads. See Fig. HY. |
Grease and engage the wheel axle from the left
side.
Before tightening the fork end clamping nut, com-
press the forks a few times to centralise the fork
leg on the axle.
Tighten the pinch nut at the bottom of the left
hand fork slider to clamp it on to the axle. Do not
over-tighten the nut as there is a danger of fractur-
ing the lug.
| ~~ BRAKE PADS
- —BRAKE DISC
o a
Fig. H9 Guiding brake disc between brake pads
6
7
8
9
If the fork action is stiff, slacken the axle nut and
the fork end clamping nut and move the forks up
and down to allow the fork tubes to take up align-
ment on the axle. Re-tighten the nuts.
If stiffness still remains, release fender stay bolts
and move forks up and down, finally retightening
the stay bolts.
No adjustment to the brake operating mechanism is
required. Apply the brake several times to refill the
caliper and restore brake pressure.
SECTION H7
DISMANTLING FRONT HUB, DISC TYPE
To gain access to the front wheel axle and bearings,
remove the wheel as described in Section H6. It is not
necessary to remove the brake disc. Proceed as
follows:
1 Unscrew the bearing locking ring (right hand
thread) from the left side of the hub using peg
spanner 063965 or, if not available, a pin punch
and hammer. If the ring is an extremely tight fit,
try tapping from different holes and heat the hub
with a gentle flame.
2 Lift away the seal and spacer.
3 Heat the alloy wheel hub with hot water only to a
temperature of 100&deg;C.
*4 Insert a bar into the bearing spacer tube and force
the spacer over fractionally. This will provide just
sufficient room to allow a drift to abut on the inner
race of the bearing to be removed.
5 Using a suitable drift to the bearing inner race
start to drive the single row bearing out. Force the
spacer tube over to the other side of the hub and
tap on the inner race at the new point. Continue
this operation until the bearing is driven out.
*At a later stage an expanding drift will become avail-
able which can be placed into the bearing inner race
and expanded by the centre bolt to grip the inner race.
The tool and bearing together can then be driven out
together from the other side of the hub.
6 Lift out the bearing spacer tube. If this has been
damaged and cannot be corrected, a new spacer
should be obtained for reassembly.
7 Using a suitable sized drift through the hub
towards the remaining bearing, drive the double
row bearing out of the hub, taking with it the
washers and felt seal.
Reassembly of the disc brake front hub is a similar
procedure to that detailed fully for the drum brake
wheel (Section H46).
Brakes, Wheels and Tires H _
SECTION H8 6 The wheel is now free to be removed, but it is
recommended that the bearings should be pro-
REMOVING AND REFITTING FRONT WHEEL tected from dirt ingress, particularly if the tyre is to
(Drum Type Brake) be changed.
To remove the front wheel, support the motorcycle
securely on the centre stand so that the front wheel is
clear of the ground. 7 Collect the left side bearing dust cover.
1 Disconnect the front brake cable at the brake cam
lever by taking out the clevis pin after removal of
the spring clip.
Refitting
2 Unscrew the brake cable adjuster.
8 Remove any rust formed on the wheel axle and
3 Release the axle pinchbolt at the bottom of the left grease lightly.
fork leg.
9 Offer the wheel to the forks and support the wheel
4 Remove the axle nut at the right hand end.
In position with the torque stop engaged with the
slot in the right fork slider.
10 Ensure that the dust cover is in position at the left
side of the front hub and push the axle home.
2
&gt;&gt; YU 11 Fit and tighten the axle nut.
| A Xx
Ly
&yuml;
A CABLE ADJUSTER (C)
\ Z
Na
+)
12 Connect and adjust the brake cable.
7
TTD
13 Take the motorcycle off the stand, apply the front
brake and depress the front forks two or three
times so that the fork legs align themselves
correctly on the axle.
CLEVIS PIN(A)
AX _ &Agrave; $ 14 Lock up the pinch bolt at the bottom of the left
fork slider.
Fig. H10 Drum front brake external features
Note: On early models, the brake backplate centre hole
5 Support the wheel to prevent it dropping and is oversize. It is thus important on these models to
remove the axle using a tommy bar through the centralise the brake by spinning the wheel and applying
cross hole at the left hand end, turning and pulling the brake fully, holding the brake on whilst tightening
the axle clear. the right-hand axle nut.
- Brakes, Wheels and Tires H
SECTION H9
FRONT WHEEL BEARING OVERHAUL
(Drum Brake)
To gain access to the front wheel axle and bearings,
remove the wheel as described in Section H8. Remove
the front brake plate with shoes and proceed as
follows:
1 Unscrew the bearing lock ring (right hand thread)
from the left side of the hub, using Peg Spanner
063965 Tool, or, if not available a pin punch and
hammer. If the ring is an extremely tight fit, try
tapping from different holes and heat the hub
with a gentle flame.
2 Lift out the felt seal and distance piece.
3 insert the front wheel axle from the brake side and
drive with a hide mallet. This will drive the double
row bearing further into the hub and at the same
time drive the single row bearing out.
CAUTION: Drive carefully until this bearing just
drops clear, or otherwise the fabricated spacer will
be damaged.
4 Withdraw the axle and reverse to enter it through
the spacer tube still in the hub.
5 Holding the axle central, drive the double row
bearing out, together with the felt retaining
washer, felt seal and outer washer.
To re-assemble, first pack the bearings with grease —
then proceed as follows:
6 Press the single row bearing into position at the
left side of the hub.
7 Fit the distance washer, plain side to the bearing.
8 Fit the felt seal and locking ring which should be
tightened fulfy&amp;vith Peg Spanner 063965 tool.
9 Insert the bearing spacer from the right, small end
first into the hub, ensuring that it is fully home
against the single row bearing. Pack the space
between the bearing spacer and hub with grease.
10 Enter the double row bearing squarely into the hub,
passing the front axle through until it enters the
opposite bearing. Drive the end of the spindle until
the double row bearing comes up against the
distance tube and stops.
11 Fit the smaller felt retainer washer, the felt seal
and large steel washer and lightly peen the latter
into. position at four points. Later models have a
push-in washer.
To complete the wheel ready for refitting, refit the
brake plate then refit the wheel to the forks as in
Section H8.
SECTION H10
FRONT BRAKE ADJUSTMENT
(Drum Brake)
Routine brake adjustment is carried out by means of the
cable adjuster (C). See Fig. H10. Correct adjustment
will allow the wheel to spin freely with the minimum
movement at the control lever.
Fig. H10 &amp; H11 show the external features of the drum
type twin leading shoe brake. Adjustment bythis means is
sufficient until such times as the brake shoes or linings
are replaced. After replacement of such parts, the lining
contact with the drum must be reset by means of the
link rod adjustment.
Twin leading shoe brake plate showing link rod
Fig. HT1
Brakes, Wheels and Tires H _
Setting the Link Rod
1 Take out the top clevis pin (F). See Fig. H10.
2 With the help of a second operator apply both the
top and bottom operating levers (B) fully, and
adjust the length of the link rod by slackening the
link rod locknut (G) and screwing the link rod (H)
in or out until with the linings still in contact with
the drum the clevis pin can be refitted.
3 Secure the link rod locknut.
4 If necessary, carry out final adjustment on the cable
adjuster.
5 NOTE: Shouid the adjustment run out at the
handlebar and cable adjusters, providing the brake
linings are examined to ensure that the rivets are
not flush with the lining friction surface, the
operating cam levers can be reversed to regain
adjustment.
FRONT BRAKE (Disc Type)
The disc brake functions by the pressure of friction pads
against the disc attached to the front wheel hub. As the
brake handlebar lever is applied, brake fluid from the
master cylinder reservoir is forced through the brake
line to the caliper to force the friction pads against the
disc.
The brake requires no adjustment since wear on the
pads is compensated for by extra brake fluid passing
from the master cylinder reservoir into the system.
SECTION H11
REAR BRAKE ADJUSTMENT
The rear brake is a single leading shoe unit and apart
from centralising the shoes in the brake drum when the
wheel has been disturbed, adjustment is carried out
purely on the cable. Refer to Fig. H4.
The rear brake is adjusted by means of the cable
adjuster at the operating lever. When the brake is fully
applied the operating lever should be approximately in
the position shown in broken lines in the illustration. If&quot;
excessive brake lining wear brings the lever past this
or
Le
position and there is no adjustment left, the brakes
should be relined.
After adjustment the wheels should rotate freely. Any
tendency to bind will dissipate power and generate heat
which will adversely affect the efficiency of the brakes.
To centralise the brake shoes in the drum and thus
achieve maximum braking efficiency, slacken wheel
spindle nut (A) apply the rear brake fully and hold on
whilst the spindle nut is retightened. Refer to Fig. H4
Fig. H12 Rear brake plate with brake shoes assembled
Note that the stoplamp switch must be adjusted as
in Section J18.
The rear brake cable is fitted instead of a brake rod to
cope with the flexibility of the engine cradle and swing-
ing arm relative to the main frame on which the rear
brake pedal is mounted. For this reason under no cir-
cumstances must a rod be substituted for the rear brake
cable.
SECTION 12
OVERHAULING DRUM BRAKES
The rear brake of all Commando models is of the single
leading shoe variety whereas the front brake (on models
without the disc brake option) is of the double leading
shoe type. The routine for changing brake shoes is
detailed separately below for the rear brake, twin leading
shoe front brake and twin leading shoe type with avail-
able high performance support plate. When sufficient
wear has taken place on the brake linings, the shoes
complete with linings or the linings only must be
renewed. Linings separate from the brake shoes are not
_ Brakes, Wheels and Tires H
supplied as spares requirements by the Factory. This is
a matter of policy brought about by the fact that the
brake linings require linishing after fitting to the shoes
and this operation must be carried out with Factory
accuracy if the brake is to be restored to full efficiency.
Rear Brake Dismantling — See Fig. H12
1
2
Remove the rear wheel as in Section H3.
Lift out the brake plate complete from the brake
drum.
Remove the springs from the shoes. This can be
done either with grip pliers or by levering carefully
with a suitable screwdriver. Take care not to
damage the spring retaining hooks on the brake
shoes. There may be a tendency for the springs to
fly when one end is released thus care should be
exercised to avoid loss.
Flatten back the tab washer and remove the two
hexagon headed screws securing the brake shoes
to the brake plate bosses.
Collect the tab washer and tie plate and lift away
the shoes.
Remove the nut securing the lever to the expander
and lift off the lever.
Withdraw the expander cam. If this is too tight to
pass through the bush in the brake plate, the area
of the expander cam inboard of the thread may
have been damaged by overtightening of the nut.
In these circumstances, this area of the expander
should be eased down such as with emery tape so
that it will pass through the bush.
Rear Brake Reassembiy
1
Clean the brake plate thoroughly and grease lightly
the expander cam boss, pivot pins and bearing area
of the expander cam.
Fit the expander cam to the plate but do not secure
yet from the other side.
Assemble the brake shoes to the pivot pins and
expander cam. If the brake shoes are of the late
type with detachable thrust pads, ensure that the
pads are in position between the shoe ends and
expander cam.
Fit the tie plate, tab washer (using a new one if
necessary) and set screws which should be
secured fully.
Tap over the ends of the tab washer to the set
screw heads.
Fit the brake shoe springs — these are very strong
and in consequence difficult to engage with the
brake shoe hooks. Attach one end of each spring,
tie a length of stout twine round the hook at the
other end and stretch the spring by pulling hard
on the twine. As the spring is held approximately
in position, guide the end home on to the brake
shoe hook using a screwdriver blade.
Fig. H13 Twin leading shoe brake
Front Brake — See Fig. H13
1
2
3
Remove the front wheel as in Section HS.
Lift out the brake plate complete from the drum.
Clamp the brake plate in a vice at the brake torque
stop peg.
Remove the circlips from both pivot pins and
collect the washers.
Brakes, Wheels and Tires H -
5
Either by careful levering or by the use of grip
pliers, release one end of each brake shoe spring.
Take care not to lose the springs if they should fly
when released. Also, take great care not to damage
the spring retaining hooks on the brake shoes.
Lift both brake shoes clear.
The brake cover plate can be dismantled further by
detaching both ends of the expander lever tie rod,
removing the nut and washer from each expander
and lifting clear both expander levers. The
expander can then be removed for cleaning and
greasing and if necessary the gauze covers can
also be removed.
Reassembly of this brake is a straight reversal of
the dismantling procedure. The brake shoes are
identical. When reassembling the brake, lightly
grease the expanders and expander bosses in the
cover plate and also the pivot pins and working
areas at the ends of each brake shoe. Take care to
ensure that the brake shoe springs are properly
fitted at both ends, and that the circlips are cor-
rectly located to the pivot pins.
Front Brake with High Performance Modifica-
tion — See Fig. H14
1
C1
Remove the front wheel as in Section H8.
Lift out the brake plate complete from the drum.
Clamp the brake plate in a vice at the brake torque
stop peg.
Flatten back the tab washers at the pivot pin set
screws and remove both set screws.
Remove the brake support plate. This may prove
tight to remove from the pivot pins and expander
cams in which case careful leverage may be
applied beneath the plate providing the support
plate is not distorted at all.
Either by careful levering or by the use of grip
pliers, release one end of each brake spring. Take
care not to lose the springs if they should fly when
released. Also take great care not to damage the
~ spring retaining hooks on the brake shoes.
Lift both brake shoes clear.
The brake cover plate can be dismantled further by
detaching both ends of the expander lever tie rod,
removing the nut and washer from each expander
and lifting clear both expander levers. The
expanders can then be removed for cleaning and
greasing and if necessary the gauze covers can
also be removed.
Reassembly of this brake is a straight reversal of
the dismantling procedure. The brake shoes are
identical. When reassembling the brake, lightly
grease the expanders and expander bosses in the
cover plate, the pivot pins, working areas at the
end of each brake shoe and expander cam end
spigots. The latter is imperative and molybdenum
disulphide grease is recommended at this point.
Take care to ensure that the brake shoe springs
are properly fitted at both ends before the brake
support plate is offered into position. If a new
support plate is being fitted, do not open the pivot
or expander cam holes at all to ease fitting, or the
whole purpose of the modification to tie the pivots
and expanders in a fixed relationship will be lost.
After fitting the plate securing screws and tab
washers, tap the tab washers into position as in
Fig. H14.
Pi
SET SCREW PIVOT PIN
TAB WASHER |_.
PIVOT PIN EXPANDER CAM
Fig. H14 Twin leading shoe brake with high performance
modification
Brakes, Wheels and Tires H
SECTION H13
NORTON LOCKHEED HYDRAULICALLY
OPERATED DISC BRAKE
This brake is a very powerful ana progressive unit
offered from 1972 as an alternative to the drum type
brake. The servicing routine is straightforward but it is
absolutely essential for the components of the hydraulic
system to be handled with particular care, avoiding any
possible marking of the bores and pistons of the master
cylinder and of the caliper since these are machined to
unusually fine limits. Similarly it is vital to exclude even
the finest particles of dirt and foreign matter from the
hydraulic system and to avoid the use of any fluid or
cleaning agent which could cause even the smallest
degree of deterioration on the rubber seals. Throughout
the following instructions, reference is made to the use
of Lockheed Series 329 Hydraulic Fluid for Disc
Brakes. This is the fluid used by the factory and recom-
mended for use in the Commando disc brake hydraulic
system in subsequent service, the fluid complying with
the requirements of USA/Canada Safety Standard 116.
The hydraulic system is sealed and the master cylinder
and caliper with hose and pipe connected can be
removed as an assembly if required without the loss of
fluid and without the need for bleeding on reassembly.
Providing the bellows seal is in situ in the master
cylinder there will be no loss of fluid even from the
breather hole in the cap.
It is not necessary to remove the caliper assembly from
the fork leg during renewal of the friction paas as
described below :
Caliper Friction Pad Renewal
1 Remove the front wheel (see Section H6).
2 Rotate the friction pads slightly and remove.
3 Inspect the friction pads for excessive wear.
uneven wear or scoring. If there is any doubt
whatsoever on the condition of the pads, obtain
new pads. It is important to replace the pads as a
pair: never attempt to replace one pad only.
4 Clean the friction pad recesses and exposed ends
of the pistons using only a small soft brush. DO
NOT utilise any solvent or wire brush for the
removal of dust, dirt or scale.
5 Smear lightly the piston faces and brake pad
recesses with Disc Brake Lubricant.
6 Remove the master cylinder cap and bellows seal
to observe the level which will rise during the next
operation.
7 Press the pistons back into the caliper, observing
the fluid level in the master cylinder to prevent
overflowing. If necessary, excess fluid can be
siphoned off.
If at this stage it is found that the pistons are locked
or seized in position and not free to move, the caliper
must be removed, drained and overhauled as described
later in this section.
8 On motorcycles using the cast iron disc, a rust
build-up may have occurred which prevents entry
of the disc between the new friction pads. Remove
any such rusting by the careful use of a fine flat file.
9 Ensure that the new friction pads are of the correct
friction type to suit the cast iron disc. It is import-
ant to consult the replacement parts catalogue
and thus obtain the correct pads. Frictional and
noise problems will arise if incorrect combinations
of disc and pads are used. Any roughness or
manufacturing flashes must be trimmed from the
edges of the metal backing plate.
CAP SEAL PISTONS
| \ )
fi &copy;
u
PISTON SEAL FRICTION PADS SEAL CALIPER
Fig. H15 Exploded view of caliper group
10 Avoiding the friction material, smear the edges of
the pad backing plates with Disc Brake Lubricant
and press fully home against the pistons.
Brakes, Wheels and Tires H -
11 Replace the front wheel as in Section H6, support
the motorcycle so that the front wheel spins freely
and apply the front brake lever at the handiebar
several times to restore the fluid in the caliper and
locate the pads correctly.
12 Restore the master cylinder level as in Fig. K8
using Lockheed Series 329 fluid and replace the
bellows seal and cap.
CAUTION: It is dangerous to ride the motorcycle
after pad and hydraulic system attention without first
applying the brake a number of times to restore pressure
and locate the pads to the disc. To avoid glazing of the
friction surfaces, the brake must be applied gently if
possible over the first 50 miles of use.
Caliper Overhaul
It is unnecessary to remove the front wheel but the hose
support bracket must be released from the central fork
mudguard bridge mounting studs and the hose to
bracket clamp nut slackened to facilitate separation of
the hose and pipe from the fork leg. Proceed as
follows:
1 Prior to releasing the caliper from the fork leg,
ease the fit of the caliper end plug which will be
very tight. This will require the use of peg spanner
tool 063965. Do not yet remove the plug.
2 Remove the two caliper bolts and washers and
swing the caliper clear of the fork leg, taking the
weight to avoid straining the brake hose.
3 Lift the two friction pads from the caliper.
4 Brush clean the exposed ends of the pistons and
the outer surfaces of the caliper body, using methyl
alcohol (methylated spirit) if required.
5 Lubricate the exposed ends of the pistons to ease
their passage through the seals.
6 Place a clean receptacle below the caliper to
receive displaced brake fluid and remove the inner
piston. The outboard piston can be removed easily
at a later stage if necessary. For this reason we
recommend the use of a clamp to restrain the out-
board piston. Apply the handlebar brake lever and
the inner piston will be ejected into the friction
pad cavity, and fluid released. Do not use any tool
or airline to remove the piston nor use excessive
pressure at the handlebar if the piston is seized.
NOTE THAT THE ONLY SATISFACTORY REMEDY
FOR A SEIZED PISTON IS RENEWAL OF THE
COMPLETE CALIPER ASSEMBLY.
7 Remove the clamp restraining the outer piston.
8 Slacken the lower brake pipe union nut and
separate the pipe from the caliper.
9 Remove the caliper end plug, drain the remaining
fluid into the receptacle.
10 Remove the piston from the caliper. If there is any
difficulty, push the piston towards the centre of
the caliper and clean carefully the outer working
surfaces of the piston, removing any traces of dirt,
dust or scale with methyl alcohol and/or metal
polish before pressing the piston back into the
caliper body and withdrawing through the end
plug aperature.
11 Using a blunt nosed tool and taking the greatest
possible care not to damage the seal grooves in
any way whatsoever, remove the pressure seal from
the outer bore.
12 Remove the inner piston through the outer
cylinder bore then with the same care remove the
pressure seal from the groove in the inner bore.
13 Pencil mark “Inner” and “Outer” on the friction
material of the pads as applicable for future
reference.
Caliper Component Inspection
Clean the pistons, caliper bores and seal grooves with
ethyl alcohol or clean brake fluid.
Examine the pistons and renew if there are any
signs of wear, damage or corrosion. No attempt
must be made to rectify damage wear or “out of
square” thrust faces by machining, filing or polish-
ing. It is permissible only to restore pistons by the
ultimate use of a fine metal polish.
Examine the caliper bores for abrasion, scratches
and corrosion, or damage to the seal grooves. The
caliper bores are not normally subject to premature
failure or wear but irreparable damage can be
caused during removal of damaged or corroded
pistons or careless removal of seals with a sharp
instrument.
After examination clean all the parts thoroughly in
methyl alcohol or clean brake fluid.
Caliper Re-Assembly
Coat the new pressure seals with Lockheed Series
329 Hydraulic Fluid and ease the first pressure seal
into the groove in the inner bore with the fingers,
taking care to bed it correctly. It will be noted that
the diameter of the seal is larger than that of the
seal groove, in order to provide an interference fit.
In addition, the seal groove and seal are different
in section so that when bedded, the seal feels proud
to the touch at the edge furthest from the bore.
This is normal.
Coat the inner piston (the pistons are identical) with
Lockheed Series 329 Fluid, insert it squarely right
through the outer cylinder into the bore of the inner
cylinder, closed end into the bore. Leave the piston
protruding approximately =; in. (8 mm) from the
mouth of the inner bore.
Fit a new pressure seal to the caliper outer bore
groove, again bedding it correctly.
Coat the second piston with Lockheed Series 329
fluid and insert it open end first into the bore with
the fingers. Avoid tilting the piston and continue
inserting it gently through the bore until approxi-
mately # in. (8 mm) of the open end protrudes
from the inner mouth of the bore.
Replace the end plug using a new “O' ring seal and
tighten into position. For final tightening, the
caliper must be secured to the fork leg.
10
— Brakes, Wheels and Tires H
Wipe the caliper clean, removing excess fluid
which may subsequently contaminate the brake
friction pads, taking care not to allow any rag
particles to pass anywhere near the brake pipe feed
union.
Fit the two friction pads and ensure that they seat
correctly.
Assemble the caliper assembly over the wheel disc
and offer the caliper to the fork leg, securing with
two bolts and washers.
Tighten the caliper end plug using peg spanner
tool to 26 |b./ft. torque.
Refit the fluid feed hose bracket to the mudguard
bridge stud.
IMPORTANT
Before connecting the lower end of the brake pipe to
the caliper, note that the pipe olive is specially formed
to provide an effective high pressure oil seal against the
caliper union seating. The olive is very susceptible to
overtightening and if it is severely distorted by over-
tightening it may be impossible to remove thus render-
ing the caliper scrap.
11
12
13
14
Examine the union olive of the metal brake pipe
for symptoms of previous overtightening such as
distortion, damage and cracks and if necessary
renew the pipe.
Offer the olive of the brake pipe to the caliper, hold
the pipe in the required position and run the union
screw fully down the thread until the pipe is just
“nipped” on to its seating. Tighten the union nut
with a spanner one flat only, i.e. 60&deg;.
Slacken the bleed nipple one full turn and connect
with a suitable bleed tube to a clean container
(see Fig. H17).
Fill the master cylinder reservoir with Lockheed
Series 329 brake fluid.
Brakes, Wheels and Tires H _
15 Operate the brake lever until fluid begins to flow in the system and a need for further bleeding) and
through the bleed tube. During this operation, examine the system for leaks.
guard against the master eylinder fluid level a
becoming too low, otherwise air will be drawn into
the system. The master cylinder bellows seal must
be removed to observe the fluid level.
17 Finally recheck the fluid level in the master cylinder
reservoir, topping up as necessary, then road test
the motorcycle.
If replenishment is necessary during this operation,
hold the lever to the handlebar whilst the reservoir Master Cylinder Overhaul
is topped up. Similarly, when fluid free of bubbles Prior to commencing work on the master cylinder it is
flows from the bleed pipe, tighten the caliper bleed desirable to obtain a supply of new Lockheed Series 329
nipple, whilst the brake lever is held against the Fluid in a sealed container. Where supplies are unob-
handlebar. tainable and the fluid may have to be re-used, it is sug-
gested that fluid is collected in a clean jar or receptacle
16 With the bleed nipple tightened up, remove the by means of a short length of clean rubber tubing from
bleed hose, apply the brake lever a number of the bleed screw to the collecting jar. Release the caliper _
times to check for sponginess (indicating air still bleed screw one full turn and operate the hand brake
LEVER
/ TRAP OR BLEED
VALVE
ASSEMBLY
CAP
INNER PLASTIC
BOBBIN
\ ; SPRING
RUBBER VALVE
BASE
BELLOWS SEAL
BODY
CIRCLIP (10 EARS)
SECONDARY CUP
PRIMARY CUP WASHER
PRIMARY CUP
SPREADER
N117
Fig. H16 Master Cylinder—Exploded view De”
_ Brakes, Wheels and Tires H
lever a number of times until the master cylinder reservoir
is empty. Close the bleed screw and detach the drain
tube. Store the collecting jar safely and cover carefully
to prevent dirt ingress.
Master Cylinder Removal
1 Disconnect the brake stop light pressure switch
spade terminals and lift away the plastic switch
cover exposing the hose union into the master
cylinder.
2 Detach the hose from the master cylinder.
3 Remove the four switch casting screws and lift
away the master cylinder complete.
Master Cylinder Dismantling — See Fig. H16
1 Remove the reservoir cap and bellows seal.
2 Remove the brake light pressure switch.
3 Remove the pivot bolt locknut and withdraw the
pivot bolt and lever.
4 Carefully prise the boot circlip from the lower end
of the master cylinder. This can be achieved if care
is taken to lift three or four adjacent segments
progressively, a little at a time until the circlip is
tipped sufficiently to clear the mouth of the
cylinder bore.
5 The boot is located into the piston and is best
removed with the piston. Lift the piston out com-
plete with boot and secondary cup.
6 Remove the primary cup washer, primary cup
spreader, spring and bleed (or trap) valve
assembly. To dislodge these items it may be
necessary either to bump the casting on a block of
clean soft wood to dislodge them or alternatively to
apply gentle air pressure at the hose union bore
and blow the parts free.
Inspection of Master Cylinder and Components
Discard the primary and secondary cups, the trap valve
and boot. Clean the master cylinder and piston in brake
fluid or methyl alcohol — do not use abrasive materials
or solvent fluids.
Inspect the master cylinder body for wear in the piston
bore. Normally, if the seals have been operating satis-
factorily no wear need be expected, but if seal failure
has occurred, the piston may have destroyed the bore
finish. If there is any doubt whatsoever, the cylinder
must be replaced.
If the cylinder is found to be fit for further service,
ensure the two cylinder ports into the reservoir chamber
are perfectly clear and clean. Inspect the hose union
and switch threads for clean and satisfactory condition,
and the lever pivot bolt bore for wear or cracks, or
fractures. Replace the master cylinder if any doubt
exists.
Check the brake lever for pivot bore wear and possible
wear on the piston thrust face. Replace the lever if
necessary. Next examine the piston for signs of scuffing
on the ground outer diameters, and any wear on the
lever thrust face.
Do not attempt to polish or grind the piston in any way,
using abrasive compounds, as the slightest residual
trace of such materials, even after intensive cleansing
will damage master cylinder and caliper working parts
bevond repair, and can result in premature brake failure.
Inspect the brake hose for cuts, signs of ieakage or
deterioration. Replace if the slightest doubt exists.
Master Cylinder Reassembly
After inspecting and cleaning the master cylinder, clean
the piston, spring, spreader and cup washer in clean
hydraulic fluid, and place in order of assembly on a
perfectly clean working surface, in a dust free room or
workshop.
DO NOT USE A FLUFFY RAG TO WIPE THE
COMPONENTS. ALLOW TO DRAIN.
Soak the new primary and secondary cups in hydraulic
fluid for fifteen minutes, kneading occasionally to
encourage the special rubber cups to gain their maximum
supple state prior to assembly. Ensure the three relief
holes in the “crown” of the piston are clear and clean.
1 Take the “hollow” secondary cup and place it non
lipped side against the ground “crown” diameter
of the piston. Work the cup over the “crown” by
hand, then down the piston body, over the
Brakes, Wheels and Tires H _
shoulder into its groove adjacent to the main body
ground diameter.
CAUTION — Do not use any form of tool to ease
assembly of the cup to the piston for fear of
damage to the lip.
2 Fit the boot over the piston open end towards the
piston crown and ensure the upper end is fitted
squarely and snugly in the piston groove. The
piston is now ready for assembly.
3 Assemble the trap valve to the spring, ensuring the
inner plastic bobbin is accurately seated in the
rubber valve base, and that the small diameter
bleed hole in the bobbin base is clear and free.
Ensure the plastic spreader is securely and firmly
pressed home on the other smaller diameter end of
the spring.
4 Offer the spring/trap valve assembly into the master
cylinder, valve end first, keeping the master cylinder
bore upright. It is permissible to hold the nose of
the casting securely in a soft jawed vice, provided
it is in no way overtightened.
5 Assemble the primary cup washer into the bore,
open end of the cup facing into the bore, followed
by the primary cup washer. Ensure only one cup
washer is employed at this point. Place this
‘dished primary cup washer, “hump” upwards,
towards the open end of the cylinder bore. (The
effect of the dished cup washer is to close the
primary cup during the return stroke, allowing oil
to by-pass the cup and replenish the pressure
cylinder). |
6 Offer the piston crown first into the cylinder. Place
the 10 eared boot circlip over the top of the boot,
the slight set on the ears facing away from the
cylinder. Ensure fluid is smeared onto the secondary
cup and into the mouth of the cylinder bore.
The next series of operations, to locate the piston,
boot and circlip by means of the brake lever and pivot
bolt can be difficult without the aid of special tools, and
the assistance of a second operator. However, if care is
taken, assembly can be completed without such help,
the difficulty being to locate the base of the boot into
the cylinder counterbore and finally locate and snug
home the circlip whilst holding the piston assembly
within the bore of the master cylinder, against the trap
valve spring, long enough (and with sufficient piston
thrust pad clearance) to be enabled to fit the hand lever
and to locate it with the pivot bolt. The method of
assembling these parts is detailed below:
7 Take the master cylinder assembly in the left hand
(having assembled up to the point as described
above) supporting the casting with the first and
second fingers under the switch boss (hose and
pressure switch threaded bores pointing down-
wards) and left thumb on the top of the casting
close to the piston thrust “pad.” Apply a gentle
rotary action with the right hand to the piston
thrust pad, at the same time maintaining down-
ward thrust pressure against the trap valve spring
assembly — ensuring the lip of the secondary cup
enters the cylinder bore freely and without damage
to the lip. When the piston has entered the bore,
move the left thumb over to maintain the piston
within the bore, at the same time using a blunt
prod to snug the lower boot shoulder into the
cylinder counter bore. Once this is seen to be
achieved, and still maintaining pressure on the
piston thrust pad, work the boot retaining circlip
down to locate and restrain the boot in position.
Still maintaining pressure on the piston thrust pad
with the left thumb, slide the brake lever into posi-
tion at the fulcrum slot, engaging the thrust pad
close to the operator's left thumb. By holding the
lever knob against the chest, alignment of the holes
can be achieved, and the pivot bolt slid into posi-
tion, and located with the locknut.
Brakes, Wheels and Tires H
Master Cylinder Refitting
Refitting the master cylinder is the exact reverse
procedure of the dismantling sequence described above.
Refit the master cylinder to the handlebar, the oil
pressure switch and brake hose. Slide the plastic switch
cover over the hose, hold in a convenient location
whilst the brake light wires are connected to the brake
switch terminals and slide the cover into final location.
Enter the lower hose into the fork support bracket,
locate in position with the locknut and tighten up the
upper brake pipe union nut. Bleed the hydraulic system
as described in the following text, after ensuring that the
master cylinder is level on the handlebar.
Bleeding the Hydraulic Brake System
1 Remove the reservoir cap and fill the reservoir
almost to the top. Remember that brake fluid ruins
paintwork and do not allow fluid to spill during
filling.
2 Connect a small bore rubber tube from the caliper
bleed screw to a clean jar or receptacle.
3 Unscrew the bleed screw one full turn and start to
pump slowly the handlebar lever. As fluid is forced
to the caliper and through the bleed nipple, the
master cylinder level will drop. Take care through-
out the operation that the level does not drop
sufficiently low to allow further air to be pumped
into the system and top up where necessary.
4 Continue pumping the lever until fluid free of air
bubbles exits from the bleed tube into the fluid
container then hold the brake lever “on” against
the handlebar whilst the caliper bleed screw is
tightened and the bleed tube removed.
5 Testthe brake for “sponginess.” If the action feels
“spongy,” then air remains in the system and
further bleeding must be undertaken.
6 Ensure that the master cylinder reservoir is brought
to the correct level then refit the bellows seal and
cap.
7 Finally check all unions for security and freedom
from leaks.
SECTION H14
TIRES
Tire changing is largely a matter of technique and what
to the layman may seem a difficult task is perfectly
straightforward when the correct technique is followed.
To change either tire, the wheel must be removed. See
Sections H6&amp;8 for front wheelremovaland SectionH1 for
rear wheel removal. The same basic principles apply for
all types of tire — lubricate the beadings such as with
soapy water, to allow the beadings to slip easily over
the rim, use heel pressure wherever possible in prefer-
ence to tire levers for easing the tire on to the rim and
minimise the risk of damage by “nipping” and ensure
that the opposite side of the tire is pressed well into the
rim well to provide maximum freedom where the bead-
ing is being slid over the wheel rim. Note: that the rear
tire only has one security bolt to prevent tire “creep”
such as under hard acceleration. No security bolt is
fitted to the front tire. For this reason separate routines
are given for front and rear tires. The full technique is
as follows:
Brakes, Wheels and Tires
Fig. H18 Levering close to valve whilst pressing opposite bead
down into rim
Removing Front Tire (No security bolt)
Remove the dust cap from the valve and using a
suitable notched type of cap or removal tool,
unscrew the valve core to deflate the tire com-
pletely.
Remove the knurled ring securing the valve at the
rim. Store the cap, core and knurled ring clean for
re-use.
Lay the wheel down, if possible on a clean surface
to avoid scratching and, also to prevent damage to
the front axle. In the case of a disc brake wheel,
leave the disc uppermost.
Tread the tire beading away from the rim — after a
great deal of service the tire beading has a
tendency to stick.
Brush a lubricant such as soapy water onto the tire
beading and rim and also dip the tire levers (two
short ones are recommended) in the solution before
each leverage.
Fig. H19 Two tire levers in use to remove first bead of tire
10
Insert the first lever between the tire valve and rim
at the valve position, press the opposite side of
the tire down into the rim well and apply leverage
(see Fig. H18).
Insert the second lever approximately 4 in. (100
mm) from the first and lever the tire beading over
the rim.
Remove the first lever and re-insert at the next
stage, continuing round the rim a little at a time
(see Fig. H19) until the beading can be pulled clear
of the rim.
Push the valve out of the rim and withdraw the
inner tube.
If it is required to remove the tire from the rim,
hold the wheel upright and apply pressure to a
lever inserted between the second beading and
wheel rim.
(
Brakes, Wheels and Tires H
Before fitting note that new Avon tyres have red and Dunlop tyres white paint dots at the lightest
point. Note also that the latest Dunlop tyres have directional arrows on the sidewalls.
Refitting Front Tire (No security bolt) 8
As shown in Fig. H23, taking care to avoid “nip-
Fig. H20
If the tire has been removed completely, ensure
that the rubber rim tape is fitted properly, rough
side towards and central in the spoke nipple area
of the rim.
Replace the valve core and inflate just sufficiently
to “round” the tube and minimise the risk of
“nipping” at a later stage. Dust the tube with
French chalk and piace.the tube inside the tire,
aligning the paint dots on the tire with the valve
stem.
Tube within cover squeezing cover to hold valve
protruding
Lay tire and tube over rim ensuring that “front
wheel rotation” arrow (if any) points in direction
of wheel rotation.
Lubricate the beadings with soapy water.
Squeeze the beadings together with the hand, per-
mitting the edge of the tube to protrude for
approximately 2 in. (50-8 mm) at each side of the
valve. Offer the tire and tube to the rim, feeding
the valve through the rim tape and rim holes.
Pressing this side of the tire into the rim well, and
working from the valve, press the first beading over
the rim by hand pressure and lever the last few
inches into position as in Fig. H22. Take special
care that the inner tube is not nipped during this
operation.
Press the second beading into the rim well, starting
opposite the valve then use the heel to press the
bead into position as far round as possible.
ping”, lever the last portion of the beading over
the rim, finishing at the valve.
Fig. H21
10
11
Refitting tire to wheel with valve engaged in rim hole
Push the valve inwards to the rim to ensure that
the tube near the valve is not trapped between the
beading and rim then pull the valve back and
inflate to pressure.
To ensure that the tire is true on the rim, check the
tire moulded fitting line in relation to the rim. The
position can be corrected by “bouncing” the side
of the tire on the ground at any point where the
fitting line is too near the rim.
When the tire is fitted correctly, fit the knurled
valve securing rim and replace the valve dust cap.
Removing Rear Tire (Security bolt fitted).
The routine for removing and refitting a tire with security
bolt is basically the same as for a tire without security
bolt but it is important to deal with this item in the
correct sequence. The full procedure is therefore
detailed as follows:
Remove the dust cap from the valve and using a
suitable notched type of cap or removal tool,
unscrew the valve core to deflate the tire com-
pletely.
Brakes, Wheels and Tires H -
Remove the knurled ring securing the valve at the
rim. Store the cap, core and knurled ring clean for
re-use.
Unscrew the security bolt nut and push the bolt
inside the cover.
Lay the wheel down, if possible on a clean surface
to avoid scratching.
Tread the tire bead away from the rim — after a
great deal of service the tire beading has a
tendency to stick.
11
12
Push the valve out of the rim and withdraw the
inner tube.
If it is required to remove the tire from the rim, hold
the wheel upright and apply pressure to a lever
inserted between the second bead and wheel rim.
Fig. H22 First bead being levered into the rim
10
Brush a lubricant such as soapy water onto the
tire bead and rim and also dip the tire levers (two
short ones are recommended) in the solution before
each leverage.
Insert the first lever between the tire valve and rim
at the valve position, press the opposite side of the
tire down into the rim well and apply leverage (see
Fig. H18).
Insert the second lever approximately 4 in. (100
mm) from the first and lever the tire bead over the
rim.
Remove the first lever and re-insert at the next
stage, continuing round the rim a little at a time
(see Fig. H19) until the bead can be pulled clear
of the rim.
Remove the security bolt from the rim.
Fig. H23 Careful levering of second bead over wheel rim
Refitting Rear Tire (Security bolt fitted)
If the tire has been removed completely, ensure that
the rubber rim tape is fitted properly, rough side
towards and central in the spoke nipple well of
the rim.
Ensure “rear wheel direction” arrow (if any), is
pointing in direction of wheel rotation and fit the
first tire beading over the rim without the inner
tube, ensuring that the paint dots align with the
security bolt hole.
Lift the free side wall as in Fig. H24 and insert the
security bolt less nut. Loosely fit the leather washer
and nut.
Replace the valve core and inflate just sufficiently
to “round” the tube and minimise the risk of “nip-
ping” at a later stage. Dust the tube with French
chalk and place the tube inside the tire, feeding the
valve through the rim tape and rim holes.
Lubricate the bead with soapy water.
: п Илл
7 E ADA 2 &lt;
A 7 —. so
| , — | .
Fig. H24 Lifting cover and engaging security bolt to rim
Pressing this side of the tire into the rim well, and
working from the valve, press the first bead over
the rim by hand pressure and lever the last few
inches into position as in Fig. H22. Take special
care that the inner tube is not nipped during this
operation.
Press the second bead into the rim well whilst
keeping the security bolt pressed back into the tire
as in Fig. H25 starting opposite the valve then use
the heel to press the bead as far round as possible
into position.
As shown in Fig. H25, taking care to avoid “nip-
ping”, lever the last portion of the bead over the
rim, finishing at the valve.
9
10
11
12
Brakes, Wheels and Tires H
Push the valve inwards to the rim to ensure that
the tube near the valve is not trapped between the
bead and rim then pull the valve back and inflate
to pressure.
To ensure that the tire is true on the rim, check the
tire moulded fitting line in relation to the rim. The
position can be corrected by “bouncing” the side
of the tire on the ground at any point where the
fitting line is too near the rim.
Bounce the tire several times in the centre of the
bead where the security bolt is fitted then tighten
the securing nut. Recheck that the fitting line is
still equidistant to the rim.
When the tire is fitted correctly, fit the knurled
valve securing nut and replace the valve dust cap.
Fig. H25 Pressing security bolt back through rim whilst levering
second bead into position
_ Electrical
Electrical
Electrical
SECTION J
DESCRIPTION
The Commando electrical system is grouped into four
areas for the purpose of this manual. The areas are:
Sections J2 Those parts connected with the charging
to J8: system.
Sections J9 Those parts connected with the ignition
to J14: system.
Sections J15 Those parts connected with the lighting
to J19: system.
Sections J20 Other electrical equipment.
to J28:
IMPORTANT +
Before starting any electrical test procedures, on 1971
and later models, isolate the 3 AW warning light
assimilator by disconnecting the green/yellow lead to
the assimilator at the alternator green/yellow lead double
snap connector. |
The Commando electrical system is positive earth
(ground).
SECTION J2
CHARGING SYSTEM
The charging system comprises an alternator with the
6 charging coils connected permanently, (fitted in the
primary chaincase and driven by the engine crankshaft).
This supplies alternating (A.C.) current to the rectifier
where it is converted to direct (D.C.) current. The D.C.
current is fed to the lead/acid battery in parallel to the
Zener diode which is mounted on the right support
plate for the silencer and footrests.
The function of the Zener diode is to regulate the flow
of D.C. current and thus prevent overcharging of the
battery. Surplus current is directed to the heatsink (in
this case, the light alloy support plate for the right hand
silencer and footrests) where it is dissipated as heat.
Below are detailed the components of the charging
system with applicabie test procedures:
SECTION J3
ALTERNATOR - LUCAS TYPE RM21
The alternator produces an alternating current (A.C.) by
means of a six-pole permanent-magnet rotor which
rotates within a stationary six-pole laminated-iron stator
assembly.
The rotor is attached to the engine crankshaft, which
revolves at engine speed. The stator sub-assembly,
comprising the windings and laminations, is attached
‘to the primary chaincase.
Maintenance
The alternator and associated equipment requires no
maintenance except for an occasional check to ensure
that all the external cable connections are clean and
tight. The rectifier securing nut should make good
electrical contact. If it should be necessary to remove
the alternator rotor from the engine crankshaft, the use
of magnetic keepers is not necessary, but keep the rotor
away from magnetically-attracted metal foreign matter.
Testing the alternator in situ
(a) Disconnect the alternator leads at the snap con-
nectors.
(b) Connect an A.C. voltmeter (with 1 ohm resistor in
parallel) as detailed in the table below. See Section
J25 for instructions on making a 1 ohm resistor.
(с) Start engine and run at approx. 3,000 rev./min.
noting voltmeter readings.
MINIMUM VOLTAGE
READINGS
VOLTMETER AND RESISTOR
ACROSS Stator: Two lead
Type: RM21
White/Green. Green/Yellow 9
Any one lead and stator earth NO READING
(ground)
CONCLUSIONS:
If the reading is low, check the rotor by substitution.
Zero reading indicates open-circuited coil(s).
Electrical
Testing the D.C. input to battery
(a) Connect a D.C. ammeter in main battery lead
(between battery negative terminal and battery
cable), red lead to cable, black lead to battery
terminal.
(b) Ensure Zener Diode is disconnected.
(c) Start engine and run at approx. 3,000 rev./min.
The following reading will be obtained if the battery
and charging systems are in good condition.
alternator
SECTION J4
RECTIFIER TYPE 2DS 506
The rectifier, which is of the silicon crystal bridge-
connected full wave type, requires no maintenance
beyond a periodic check on the cleanliness and security
of the terminals. If for any reason the rectifier is
removed, DO NOT twist the plates in relation to one
another since this will break internal connections and
render the rectifier unfit for further service. The centre
bolt must be held with a spanner whilst the fixing nut is
turned.
VOLTMETER AND
MINIMUM VOLTAGE
~ RESISTOR ACROSS READING
Rectifier (Centre Terminal |
and Earth (frame) 7-5
— 000000 — GY N
WG TT
Fig. J1
“—
Switch Positions Minimum Current Reading
Ignition Only 4:5 Amp
Ignition and Lights 1:0 Amp
(Main Beam)
CONCLUSIONS:
If the readings obtained are higher than the figures
quoted, the system is satisfactory. If the readings are
lower, proceed to test the alternator itself as in the
preceding text.
one ohm
resistance voltmeter
Alternator test
~~
from the harness
= remove the
centre
connector
&quot;AA
a | N vol&iacute;meter
tachine one ohm
rame resistance
rectifier
A
Л -
Fig. J2 Rectifier test connections —
+
_ Electrical
Testing the rectifier
With alternator leads connected correctiy to main
harness:
(a) Disconnect lead from centre terminal at rectifier.
(b) Connect D.C. voltmeter (with 1 ohm resistor in
parallel). Red lead to earth (frame), black lead to
rectifier centre terminal (see Fig. J2).
(c) Start engine and run at approx. 3,000 rev./min.
CONCLUSIONS:
If meter reading is equal to, or higher than the value
stated, the rectifier is satisfactory. A low reading indi-
cates a faulty rectifier. Remove and bench test.
battery
O
headlamp
bulb
о о &copy;
D
|
Bench testing the rectifier
Connect a 12 volt, 45-50 watt bulb and 12 volt battery
across terminals 2 and 1 (for a period not exceeding 30
seconds). See Fig. J3.
Repeat test with reversed battery polarity.
Carry out similar tests on terminals: Bolt and 1, Bolt
and 3, 2 and 3.
The test lamp should illuminate fully in one direction
only for each of the connections made.
CONCLUSIONS:
Rectifier must be replaced if:
(a) Bulb shows sign of illumination in for each
both direction connection
(b) Bulb shows no sign of illumination made.
in either direction
diode arrangement
&copy;
N101
rectifier
Le &copy;)
FIRST TESTS
REVERSE DIRECTION TESTS
Fig. J3
Bench testing rectifier
Electrical
SECTION J5
Zener Diode
The Zener Diode is a semi-conductor device that
becomes conductive in the reverse direction at a critical
but predetermined voltage.
Assuming the battery is in a low state of charge, its
terminal voltage (the same voltage is across the diode)
will also be low, therefore the maximum charging
current will flow into the battery from the alternator. At
first none of the current is by-passed by the diode, the
latter being non-conductive due to the low battery
terminal volts. However, as the battery voltage is
restored, the system voltage rises until, at approximately
14 volts, the Zener diode becomes partially conductive,
thereby providing an alternative path for a small part of
the charging current. Small increases in battery voltage
result in large increases in Zener conductivity until, at
approximately 15 volts, about 5 amperes of the alternator
output is by-passing the battery. The battery will con-
tinue to receive only a portion of the alternator output as
long as the system voltage is relatively high.
Depression of the system voltage, due to the use of
headlamp or other lighting equipment, causes the
Zener diode current to decrease and the balance to be
diverted and consumed by the component in use. If the
electrical loading is sufficient to cause the system volt-
age to fall below approx. 14 volts, the Zener diode will
revert to its high resistance state of virtual non-
conductivity and the full generated output will go to
meet the demands of the system.
When refitting a Zener diode, the contact between
the diode and the heatsink must be clean and free from
corrosion. The tightening torque for the retaining nut is
24—28 Ib./ins. (3-32-3-87 kg/m).
Testing the Zener Diode
(a) Connect D.C. ammeter between Zener Diode
Lucar Blade and feed cable (Red lead to Zener,
Black lead to cable). |
(b) Connect D.C. voltmeter between the Lucar terminal
of the Zener Diode and earth (Red lead to earth,
Black lead to Zener Lucar Blade).
(c) Ensure all lights are switched off and any acces-
sories unplugged.
(d) Start engine, slowly increase speed and check
meter reading.
Special Note: THE BATTERY MUST BE IN A
FULLY CHARGED STATE. If the battery condition is
poor it should be temporarily replaced by a known good
battery.
CURRENT DIODE VOLTS
Nil Up to 12:75
2 Amp 13:5 10 15:5
CONCLUSIONS:
Zener Diode must be replaced if:
(a) Current flow commences before 12-75v is reached.
(b) Voltmeter registers more than 15-5v before 2 amps
is shown on the ammeter.
SECTION J6
BATTERY
Lead acid batteries are used on all models. On Com-
mando models excepting Interpol, a single Lucas
PUZ5A 12 volt battery with translucent case is fitted.
Later models use Norton Villiers battery 063244 or
Yuasa 12N9-4B. On Interpol, two Lucas type SCZ7E
6 volt batteries are fitted in series. On both battery types,
the acid level can be seen through the casing and the
electrolyte level is marked clearly on the battery case. A
breather vent is used on both types of battery.
Battery Maintenance
Due to continual evaporation and gassing during
charging, a weekly inspection must be made on the
electrolyte level. Since the level will normally rise whilst
the battery is being charged, the level must only be
checked during off-charge periods. Any loss of electro-
lyte should be made good by the addition of distilled
water until the level mark is reached. The level should
not exceed this mark, for spillage may occur with subse-
quent damage to surrounding parts.
It is important to keep the battery connections clean
and tight. Dirt and moisture must be wiped away from
the battery top periodically.
If the motorcycle is stored for a period, the battery
should be removed and maintained in a good state of
charge every two weeks.
—
—
Electrical
Checking the state of charge
A hydrometer is required for this check. The specific
gravity should be checked for each cell and the results
checked with the table below:
SPECIFIC GRAVITY
(Corrected to 15&deg;C (60&deg;F) )
Climates normally | Climates normally
below 25&deg;C above 25&deg;C
(77&deg;F) (77&deg;F)
Fully Charged 1-270 - 1-290 1-210 - 1-230
70% Charged 1-230 — 1-250 1-170 — 1-190
Discharged 1-110 -1-130 1-050 — 1-070
Electrolyte temperature correction:
For every 10&deg;C (18&deg;F) below 15&deg;C (60&deg;F) subtract
0-007.
For every 10&deg;C (18&deg;F) above 15&deg;C (60&deg;F) add 0-007.
A variation of more than 40 points (0-040) between
any cells indicates that the battery is suspect and should
be thoroughly checked by the battery manufacturer's
agent.
High rate discharge check
(Battery must be at least 70% charged).
Connect voltmeter and high rate discharge resistance
(0-5 ohm) across battery terminals for 15 seconds.
Direetly after 15 seconds the reading should remain
steady.
A lower or rapidly falling voltage indicates the battery
requires charging or has a faulty cell.
BATTERY VOLTAGE VOLTMETER READING
12 9-4
6 | 4:8
SECTION J7
FUSE
A 35 amp fuse is fitted into the battery live (negative)
lead close to the battery terminal. The fuse is of the
cartridge type, in a nylon holder.
Access to the fuse is gained by pushing the fuse-
holder body halves together and twisting. At no time
must the value of 35 amps be exceeded.
SECTION J8
WARNING LIGHT ASSIMILATOR
Lucas Type 3AW (1971 and later models)
This is an electro-mechanical device for ignition warning
light control.
With the ignition switched on, the warning light is
supplied with battery current; when the engine is
started and the alternator output reaches 6 volts
approximately, the contacts inside the unit open and
break the warning light circuit, switching off the warning
light.
Should the warning light fail to light when the ignition
is switched on and with the engine stationary, discon-
nect the White/Brown lead from the “W L&quot; terminal of
the control unit and temporarily reconnect to the “E”
terminal ; if the bulb lights, this indicates that the control
unit is faulty, but should the light still fail, then the bulb,
connections, and associated wiring should be checked.
SECTION J9
IGNITION SWITCH (Pre 1971)
The ignition switch is mounted at the front of the left-
hand accessory cover. This switch is of the on/off type
governing only the ignition circuit. Clockwise rotation
turns the ignition “on” and anti-clockwise “off.”
SECTION J10
MASTER SWITCH (1971 and later models)
The key operated switch is located to the front of the
left hand accessory cover. The switch controls ignition
and also energises the lighting system. The switch is a
sealed unit requiring no attention other than a routine
check on connections. The four switch positions are
shown below in Fig. J4.
The Switch Positions are :
1. Parking Lights Only
The key may be removed in this position enabling
the machine to be parked safely at night.
2. Off Position
Again the key may be removed leaving all circuits
isolated.
3. Ignition Only
The key cannot be removed. This position is used
during normal daytime running.
Electrical
4. Ignition and Lights
Again the key may not be removed. This position is
used for night riding.
The lock with keys is captive in the switch body. If
for any reason the lock need be replaced, it can be
removed from the switch body to which itis held captive
by a spring operated plunger. A sharp pointed implement
such as a ground-down spoke would be ideal for
depressing the plunger through the. hole in the side of
the switch body. Whilst depressing the plunger the
switch body should be shaken and the lock ejected.
OFF
PARKING
WITH LIGHTS IGNITION ONLY
IGNITION AND
LIGHTS
Fig. J4 Master switch positions
SECTION J11
TESTING IGNITION SYSTEM
Testing Sequence for Ignition System
Engine; will not start — difficult to start — misfires.
(a) Check battery.
(b) Check main fuse (if fitted).
(c) Check for spark at both spark plugs.
(d) Ensure timing, contact breaker and spark plug gaps
are satisfactory.
(e) Check capacitor by substitution.
(f) Check wiring for loose connections.
(g) Test Zener Diode and ignition system.
(h) Where fitted, check ballast resistor for short cir-
cuiting, when hot.
J
Ignition System Tests
(a) Connect D.C. voltmeter Black lead to C.B. terminal
of contact breaker and Red lead to earth.
(b) Ensure contact points are open.
(c) Switch on ignition. Voltmeter should indicate
battery volts.
(d) Ignition still on, close contact points. Voltmeter
reading should fall to zero.
Note: Repeat the test for each coil with its appropriate
contact set.
CONCLUSION:
No reading for test (c) may indicate faulty ignition
switch, open circuit primary winding, broken lead, short
circuit to earth on C.B. lead, faulty capacitor or blown
main fuse.
Low reading indicates high resistance in the primary
circuit or across ignition switch contacts. A reading for
test (d) indicates voltage drop across the contact points
(dirty) or poor distributor earth.
SECTION J12
IGNITION COILS
The ignition coils whether of the 12 volt or 6 volt type
consist of primary and secondary windings wound con-
centrically about a laminated soft iron core, the
secondary windings being next to the core.
The primary winding usually consists of some 300
turns of enamel covered wire and the secondary some
17,000 — 26,000 turns of much finer wire — also
enamel covered. Each layer is paper insulated from the
next in both primary and secondary windings.
When the contact breaker opens, causing a sudden
cut-off of current flow in the primary windings, H.T.
current is induced in the secondary windings and a
spark occurs at the spark plug.
Note: The coils are of the oil filled type and must be
protected from mechanical damage which will cause
leakage.
-_ Electrical
IGNITION COILS LUCAS TYPE 17M6 (6VLOT)
1971 and later Models
Six volt ignition coils are used in conjunction with a
ballast resistor to allow their use in an otherwise 12 volt
electrical system. This system has been adopted since
an adequate spark is available with the battery in a
heavily discharged state. The ignition coils are sealed
units, requiring only a periodic check on connections.
IGNITION COILS LUCAS TYPE 17M12
(12 Volt) — Certain 1972 Models
Twelve volt ignition coils, again of the oil filled, sealed
type, are used on some model sand require no ballast
resistor.
TESTING AN IGNITION COIL
(17M6 and 17M12 Types)
An electrical test set is necessary for full testing of the
ignition coil and though a similar set-up can be
produced as shown in F/g. J5 provision will have to
be made for a contact breaker which can be motored at
100 r.p.m. Use a 6 volt battery for this test.
+
1 :
IONISING
ELECTRODE
CONTACT BREAKER 1
HT. IGNITION COIL _ UNIT =
TERMINAL * CB. OR+VE
ess TERMINAL |
SW.OR-VE | — y
L
TERMINAL | —
Loco -
| Го / &gt;]
l
N113
Fig. J5 Ignition coil testing arrangements incorporating 3 point test
Before commencing the main test, check the condi-
tion of the primary windings. This is done by connecting
an ohmeter across the low tension terminals. At 20&deg;C
the minimum resistance should be 1-7 ohms and maxi-
J
mum resistance, 1:9 ohms for 17M6 (6 volt) coils and
3:3 ohms minimum and 3-8 ohms maximum resistance
for 17M12 (12 volt) coils.
Set the adjustable gap to 8 mm for the 6 volt coil or
9 mm for the 12 volt coil and connect up as in Fig. J5.
If the coil is in good condition, sparking should occur
regulariy with no more than 5% missing per 15 seconds.
BALLAST RESISTOR
(With 6 volts coil, 1971 and later Models)
This permits the use of 6 volt coils in an otherwise 12
volt system. The two coils are wired in parallel with the
resistor in series. When the battery voltage has dropped
due to heavy current taken such as by the use of an
electric starter, the ignition coils are fed direct, by-
passing the resistor and thus enabling the coils to work
at their approximate potential. The ballast resistor can
only be tested against its resistance value of 1 -8—2 ohms.
CONTACT BREAKER ASSEMBLY — LUCAS
TYPE GCA
The contact breaker and auto advance mechanism are
covered fully in Section C39 &amp; C40 adjacent to engine
ignition timing details.
SECTION J13
CAPACITOR PACK TESTING
The capacitors can be tested in situ. To test, turn on the
ignition and take voltage readings across each set of
contacts when open. If no reading is gained, the capaci-
tor is unserviceable due to a breakdown of the internal
insulation. If a reading is gained but the capacitor has
reduced capacity, evidenced by excessive arcing and
severe burning of the contact points, a new capacitor
should be substituted on the affected cylinder.
CHANGING A CAPACITOR
(1971 and later Models)
Remove the complete coil cluster (see Section C1).
Release the capacitor pack (2 screws and nuts).
Remove the rubber cover: the individual capacitors are
retained to the base plate by singie nuts.
Electrical
Reassembly is a direct reversal of the foregoing. Take
care to reconnect the wiring correctly. If necessary
consult the wiring diagram at the end of this section.
CHANGING A CAPACITOR (1970 Models)
The capacitors are screwed individually to the coil clips
and are accessible from beneath without disturbing the
coils.
SECTION J14
SPARK PLUGS - CHAMPION N7Y
Protruding nose self-cleaning spark plugs are fitted. It
is most important to use the correct heat grade since a
spark plug of too low heat grade can cause pre-
ignition and subsequent damage to the engine.
To avoid damage to the insulator, use the plug spanner
provided in the tool kit to remove and refit the spark
plugs. The spark plugs should be tightened firmly (not
excessively) to ensure a gas tight joint.
When adjusting the gap to the recommended setting
of -028 in. (-59/-72 mm), only the side contact must be
adjusted. Under no circumstances attempt to bend the
centre electrode to adjust the gap.
SECTION J15
LIGHTING SYSTEM (1971 and later Models)
The lighting system operates on direct current drawn
from the battery (or from the rectifier where the 2MC
capacitor replaces the battery) and controlled by the 4
position master switch (described in Section J10). As
the master switch is turned to the “lights on” position,
the tail lamp, instrument lights and pilot lamp illuminate.
Selection of headlamp illumination is controlled by the
switch in the top of the headlamp shell. Headlamp high
beam or dip beam are selected by the two position
switch included in the handlebar right switch cluster.
When high beam is selected, a warning light in the head-
lamp shell illuminates.
LIGHTING SYSTEM (1970 Models)
The lighting system operates on direct current drawn
from the battery and controlled by the 3 position toggle
switch in the headlamp shell. Left position is “off”,
centre position is “pilot lights”, and right position is
main beam.
When high beam is selected, the warning light in the
headlamp shell illuminates.
J
SECTION J16
HEADLAMP
TO CHANGE THE HEADLAMP AND PILOT
BULBS
Release the screw on top of the headlamp shell
adjacent to the rim. The rim with light unit can then be
lifted out from the top first. Press down the main bulb-
holder towards the reflector and rotate counter clock-
wise. The holder will lift away and the bulb can be
removed.
The pilot bulbholder complete with pilot bulb should
be pulled away from the light unit. The bulb is a bayonet
fitting into the bulbholder.
Note: Do not touch a quartz halogen bulb envelope
with the fingers. Accidental marks can be removed with
alcohol.
SECTION J17
TO CHANGE THE TAIL/STOPLAMP BULB
The lens is secured by two bright plated screws
Release these and lift away the lens and thin gasket. The
bulb is a bayonet fitting into the bulbholder. Note that
the bulb will only fit the correct way into the bulbholder
on reassembly. Take care not to crack the lens by over-
tightening the screws.
SECTION J18
STOP SWITCHES
Front Brake Stop Switch (Drum Brake)
This is a sealed compression switch fitted into the front
cable which cannot be serviced. Check periodically on
the cleanliness and security of the spade terminals.
—
-—
I
Electrical
Front Brake Stop Switch (Disc Brake)
A sealed Lucas compression switch is incorporated in
the master cylinder. This unit cannot be serviced though
a check should be made periodically on the cleanliness
and security of the lead terminals.
Rear Brake Stop Switch — Lucas Type 118SA
The switch is a sealed unit though the rubber should be
lifted and filled with grease at intervals to exclude water.
It is mounted by screws in slots to allow for position
adjustment.
Rear Stop Switch Adjustment
Care must be taken during adjustment since incorrect
positioning causes the plastic switch to function as the
brake pedal stop, resulting in failure of the switch body.
Slacken the nuts and screws holding the switch to the
platewith slotson the brake pedal. Set therearbrake pedal
to suit the riders preference — this is done by adjustment
of the stop bolt and locknut. Adjust the rear brake cable
to the desired setting. Move the switch up, a little at a
time, until the switch plunger is central to the abutment
and until the least depression of the pedal causes the
stop light to illuminate. The recommended switch
depression is +4; in. (0-0793 mm). Tighten the switch
securing screws and allow the pedal to return to rest,
ensuring that the switch is not fully compressed before
the pedal stop is reached.
SECTION J19
HANDLEBAR SWITCH CLUSTERS
(1971 and later Models)
The switch clusters are accommodated in light alloy
“castings. Whilst the switches are not sealed units, the
method of assembly renders reassembly by an owner or
dealer extremely difficult, if not impossible, and we must
recommend against attempts at dismantling.
The right switch cluster includes, at the bottom, the
kill (or cut-out) button and a spare button at the top.
The 3-position flick switch operates the direction
indicators which are available as optional extras. The
switch functions as below:
J
1 With the lever in the central position and no but-
tons being pressed, the only leads connected are
the White and White/Yellow. This is because the
lower push button operates a normally closed (i.e.
push to open) switch.
2 Pressing the lower push button opens the White-
White/ Yellow leads (Ignition cut-out).
3 Pressing the upper push button connects the
White lead to the White/Red lead. This button has
no function at the present.
4 Moving the switch lever to the upper position con-
nects the light Green/Brown lead to the Green/
Red lead (L.H. indicators where fitted).
5 Moving the switch lever to its lower position con-
nects the light Green/Brown lead to the Green/
White lead (R.H. indicators where fitted).
The left hand switch cluster accommodates the horn
button (at the bottom), the headlamp flasher at the top
and the two position dip switch. The headlamp flasher
permits the headlamp to be flashed as an overtaking
warning when the lights are not switched on.
The lever on this switch has only two positions, up-
ward and horizontal.
1 With the switch lever in the horizontal position and
no buttons being pressed the only 2 cables con-
nected are Blue and Blue/Red (Dip beam).
2 Moving the lever to its upper position connects the
Blue lead to the Blue/White lead (Main beam).
3 Pressing the lower button connects the White lead
to the Purple/Black lead (Horn).
4 Pressing the upper button connects the White lead
to the Blue/White lead (Headlamp flasher).
Note : These clusters may easily be reversed from side
to side depending upon owner preference.
SECTION J20
POWER TAKE-OFF SOCKET
(1971 and later Models)
This is located on the front of the airbox or on 1972
models, on the right side of the battery carrier, and
provides a power source for any accessory selected by
the owner, providing the battery capacity is borne in
mind. With the battery in good condition and fully
Electrical
charged, the maximum rating of 8 amps at the 10 hour
rate is available. We recommend that the engine is run
up as soon as possible after the power take-off socket
has been used to restore the battery to a good state of
charge.
Caution must be exercised not to discharge the battery
completely. The same power socket is used for charging
the battery from an outside source.
SECTION J21
FLASHING DIRECTION INDICATORS
Bulb replacement
To replace the bulb, unfasten the screws retaining the
lens and carefully remove the lens. The bulb is then
removed by pushing inwards and rotating anti-
clockwise. When replacing the lens, ensure that the lens
body locates into the sealing gasket, before the retaining
screws are tightened.
Checking for faulty operation
If a fault occurs in the system, the following procedure
should be adopted.
1 Check that the bulb filaments are not broken.
2 Check that all flasher circuit connections are clean
and tight.
3 Switch on ignition and check with a voltmeter tha
the flasher terminal “B” is at battery voltage.
4 Connect together flasher unit terminals “B” and
“L” and operate the indicator switch. If the flasher
lamps on the respective side now light without
flashing, the flasher unit is faulty and should be
replaced with the same type of unit as the original.
If a flasher lamp stalk is replaced
On reassembly, take care not to damage the green lead
when passing through the screw thread of the lamp
shell. Final adjustment of the lamp position must be
made by tightening of the locknut and not by straining
the flasher unit.
J _
important
When tightening the stanchion locknut against the
body of the flasher lamp, ensure that the torque loading
figure of 35—45 Ibs./ins. is not exceeded.
Flasher Unit Lucas Type 8FL
The unit is clipped into the mounting bracket and if for
any reason the bracket is to be removed, the unit must
first be withdrawn from the clip.
SECTION J22
ALTERNATING HORN SET INTERPOL ONLY
TYPE HC3 |
SPECIAL NOTE: This equipment is not available in
U.S.A.
The alternating horn set comprises an alternating
horn control, special 9H horns, two 6Ra relays, a switch
and suitable connectors. Details of the individual units
are as follows :
HC 3 Alternating Horn Control
This is a transistorised multivibrator, designed to pulse
two 6Ra continuously rated relays alternately. The fre-
quency of the unit is set during manufacture and cannot
readily be altered. Hence the risk of faulty setting due to
tampering is eliminated. The unit must be mounted so
that its temperature does not exceed 50&deg;C. Connection
polarity must be observed. The alternating horn wiring
is shown in Fig. J6.
Horns
These are type 9H and have been reset after a “running-
In” period to ensure maximum life. They must be rigidly
mounted on a solid member of the vehicle with no
loosely mounted components in the vicinity otherwise
the tone will be adversely affected. It is recommended
that the horns are mounted facing forward. The flares
should be tilted slightly downwards to allow any water
entering the horn trumpets to drain out.
— Electrical
Relays
Standard 6Ra continuously rated relays are used. These
should be so positioned that the cables carrying the
horn current are as short as possible.
Technical Data
Frequency of Notes 438-495 Hz
Ratio of Notes 8:9
Sound Intensity 90 dB at 50 ft. (15-24 m)
Cycle of Signal 1-1-2 Hz
Power Consumption 60 watts
e
Testing Procedure
If the horns do not sound when the switch is operated.
check the voltage at the HC 3 control as follows :
1 Connect a voltmeter, red lead to the cable removed
from the +ve terminal, black lead to the cable
removed from the —ve terminal. Operate switch,
voltmeter should read the nominal voltage of the
system.
If the voltage is satisfactory at the control unit proceed
to check the individual horns and relays separate from
the control unit as follows :
1 Remove leads from one “R” terminal and the +ve
terminal on the control unit and join together.
Operate switch, the relay should be energised and
the associated horn should sound, if satisfactory.
J
2 Repeat above operation by joining together the
leads removed from the other “R” terminal and the
+ve terminal. |
3 [If both horns and relays operate normally, the fault
is in the HC 3 control unit. Replace unit.
4 If either horn does not sound, check further by
earthing leads connected to “C1” in the relay. If
horn now operates satisfactorily, the fault is in the
relay. Replace unit.
Other faults, i.e. : continuously sounding horns, incor-
rect cycle of operation, etc., can be attributed to a faulty
control unit, which should be replaced.
Retuning the 9H Alternating Horns
After horns have been in use for a long period there will
probably be a deterioration in performance due to
normal wear of the contact breaker mechanism. If the
rest of the system is in order, proceed to reset the horn
contacts as follows:
— Contact Adjustment on Motorcycle
1 Connect a voltmeter across the terminals of the
horn, to check the voltage as the adjustment is
being made.
2 Connect an ammeter (range 0-25A) between ter-
~ minals “C1” and “C2” of the relay which supplies
the horn to be tuned.
PUSH
— eee
— wi
FEED 6RA RELAY C1
о о ||
&quot;HORN HORN
FROM BATTERY
c2 +
N105
7 | Fig. J6 Alternating horn circuit
Electrical
3 The adjustment screw should be tuned while
operating the horn until the ammeter indicates the
appropriate current consumption (see below).
Turn the screw clockwise to reduce the ammeter
reading.
NOTE:
1 Do not under any circumstances disturb the centre
core slotted screw and locknut.
2 It is essential, when adjusting on the vehicle, that
the wiring is not overloaded. This could be caused
by attempting to sound the horn, while the con-
tacts are out of adjustment, and hence do not
open. If the horn supply is fused, the fuse should
beshorted out until adjustment has been completed.
Contacts Setting Data
High Note Horn
Setting Current
3-0 — 3:5A
Special Low Note Horn
Setting Voltage
12 volt 13 voits
Setting Current
3-0 — 4 OA
Setting Voltage
12 volt 13 volts
Horns should be checked for a good clear note over the
following voltage range.
12 volt 11-12-15 volts
SECTION J23
HORN ADJUSTMENT (SINGLE STANDARD
HORN)
The horn is shown in Fig. J7 with the adjustment screw
arrowed. Adjustment will take up wear on the moving
parts which, if not attended to, will cause roughness
and a loss of performance.
To adjust the horn, operate the horn button and slowly
turn the adjustment screw anti-clockwise until the horn
just fails to sound. Release the horn button and turn
the adjustment screw clockwise one notch at a time
until the original performance is regained. The amount
of adjustment may be expected to vary between a
quarter and three-quarters of a turn. Note that if
original performance is not restored, the horn must
receive attention by the electrical manufacturer.
Fig. J7
Horn in position—note cross headed adjuster screw
for horn contact breaker (arrowed)
SECTION J24
ELECTROLYTIC CAPACITOR 2MC
The capacitor is an electrolytic polarised type, spring
mounted to the rear of the battery. This unit will be
damaged beyond repair if it is connected incorrectly.
The small (-&amp; in.) terminal is the Positive ground (earth)
terminal with a red spot on the terminal rivet. The double
terminal is the Negative connection. The capacitor
should only be fitted with the terminals pointing down-
wards. The battery may be removed altogether or be
completely discharged whilst the 2MC capacitor per-
mits normal starting and running. With the capacitor in
use, the lights may be used whilst the engine is running
though there is no parking facility.
Periodically the capacitor should be tested by dis-
connecting the battery terminals — the negative terminal
should be insulated to prevent a possible short circuit.
Start and run the engine — full lighting should be avail-
able. If the engine fails to start and run, test as follows:
(a) Disconnect capacitor.
(b) Connect capacitor direct to 12 volt battery for 5
seconds (see polarity note).
(c) Disconnect battery and let charged capacitor stand
for 5 minutes.
(d) Connect D.C. voltmeter across the terminals (see
polarity note) and note the steady reading * which
should not be less than 9v for a serviceable unit.
*Some meters may show immediate needle overswing
which should be ignored.
м
Electrical
Polarity note: 2MC capacitors are polarity conscious
and correct battery connection must be made. The
smaller Lucar terminal blade (rivet marked red), is posi-
tive and the larger double Lucar connector torms the
negative terminal.
Conclusions:
If meter reading is less than 9v, capacitor is leaking
(inefficient) and must be replaced.
SECTION J25
HOW TO MAKE UP A ONE OHM RESISTOR
The 1 ohm resistor must be accurate otherwise correct
voltage (or current) values will not be obtained.
A suitable resistor can be made from 4 yards 18 S.W.G.
(-048 in. dia.) NICHROME wire together with two
flexible leads and suitable crocodile clips, see Fig. J8.
To Calibrate
Bend the wire into two equal parts.
(a) Fix a heavy gauge flexible lead to centre bend of
the wire, and connect this lead to the positive
terminal of a 6-volt battery.
(b) Connect a voltmeter across the battery terminals.
(c) Connect an ammeter to the battery negative post.
(d) Take a lead from the other terminal of the ammeter,
connect a crocodile clip to it, and connect to the
free ends of the wire (which should be twisted
together).
(e) Move the clip along the wire, making contact with
both wires until the discharge reading on the
ammeter exactly equals the number of volts shown
on the voltmeter. The resistance is then 1 ohm.
(fy Cut the wire at this point, twist the two ends
together and fix a second heavy gauge flexible
lead.
(g) Wind the wire on to a hollow asbestos former
2 in. dia. (approximately).
Electrical
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Fig. JIO
Electrical
Han =v
BATTERIES
MAIN BEAM
WARNING LIGHT
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COLOUR
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1972 and 1973 wiring diagram.
Fig. J11
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_ Routine Maintenance
Routine
Maintenance
Routine Maintenance
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Routine Maintenance
SECTION K1
BREAKING IN
In the process of manufacture the best possible materials
are used and all machined parts are finished to a very
high standard but it is still necessary to allow the moving
parts to “bed in” before subjecting the engine to maxi-
mum stresses. The future performance and reliability of
the engine depends on the care and restraint exercised
during its early life.
For the first 500 miles, tirottle openings should be
limited to about one-third of twist grip movement and
the cruising speed should be varied as much as possible
within this limit. Provided the engine is not allowed to
labour, the actual road speed is relatively unimportant
but throttle contro! should be smooth and the gearbox
used to the full to enable the engine to cope with the
prevailing conditions without undue stress. This will
also assist in “break-in&quot;’ of the gearbox components. At
all times avoid violent acceleration.
After the 500 miles service the amount of throttle
opening can be increased progressively but the cruisins
speed should still be varied. Full throttle should not be
used until the machine has covered at least 1,000 miles
and even then only for short bursts until 1,500 miles has
been covered, whereupon maximum performance may
be sought whenever desired.
During the “break-in” period, a certain amount of
adjustment will be necessary as the components bed in.
Attention should be given to valve rocker adjustment,
chain tension. contact breaker points gap and brakes, all
of which tend to settle down.
Do not allow the oil tank level to fall too low as
with the reduced amount in circulation the oil will
become unduly hot.
On motorcycles equipped with the disc brake, it is
most essential to avoid glazing of the friction surfaces
during the first few miles of use. During the first 50 miles
only it is necessary to apply the disc brake gently to
mate the friction surfaces. After 50 miles of use, the
brake will be fully bedded down and ready for maximum
application.
SECTION K2
ROUTINE MAINTENANCE
INTRODUCTION
This section tables the maintenance periods for various
operations, co-relates these operations to other sections
of this manual and details those operations not failing
within the normal scope of the overhaul sections.
Routine Maintenance
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Routine Maintenance
K
SECTION K3 Every |
6,000 miles
MAINTENANCE TABLE (10000 Km) Change gearbox oil К5
The following table lists the normal servicing operations, Change oil in forks | K9
the section numbers affected and the servicing intervals. Check and adjust camshaft chain K16
The service carried out after the motorcycle has com-
pleted its first 500 miles is deliberately omitted, being Clean contact breaker points C40
outside the scope of normal routine maintenance and Lubricate contact breaker cam
being covered in detail elsewhere. feltand auto advance unit C39 &amp; C40
Grease brake expander lever
Section pivots H5 &amp; H12
Weekly Check tire pressures and
wheel alignment K15 (one stroke of grease gun)
Fit new air filter element E10 )
Every two Check battery electrolyte a —
weeks level K13 Check and oil swinging arm bushes
Check and oil swinging
Every 250 Check engine oil tank level K4 armbushes KTO
miles (400 Km) Check loose or unequal spoke
| tension — front and rear wheels
Every 500 Check and adjust raer chain C41
miles (800 Km) Check front and rear wheel
В spindle clamp and nut tightness
Every |
1,000 miles Check primary chaincase oil Check front and rear tire tread
(1600 Km) level K8 р '
Oil all control cables —_— Rebalance wheels where
necessary
Adjust both brakes (disc
brake is non-adjustable) H12/13
Check disc brake fluid level K12
Examin disc brake pads for wear H16 Every Re-pack wheel bearings (including
o: 12,000 miles the rear wheel sprocket bearing) _
Examin disc pads for wear H16 (20000 Km) with grease H4 &amp; H10 ~~
Every ; Dismantle and clean both
3,000 miles Check timing and adjust contact |
(5000 Km) breaker points C38 carburetors and check for wear E3
Clean spark plugs and set gaps K12 Check rear chain for wear
. . . and adjust C41
Change primary chaincase oil K7
Check clutch adjustment C35
Check primary chain adjustment C41
Change engine oil and cartridge See Table of Recommended Lubricants
filter (where fitted) K3
Relubricate and adjust rear chain C41 Check steering head bearings
Check gearbox oil level K4 Check head steady and head
Grease rear brake pedal pivot H13 steady mounting rubbers
Check Isolastic mounting for
Check and tighten all front mounting
free play F13/14 and rear engine bolts
Check and adjust valve rocker C10 ).
clearances
Check swinging arm spindle —
—
Routine Maintenance
SECTION Ka
ENGINE OIL TANK LEVEL
The oil tank content is indicated on a dip stick incor-
porated in the tank filler cap which is removed by
pressing and turning the cap anti-clockwise.
Access to the tank filler cap is made by : releasing the
two hand discs retaining the rider's seat, raising the seat
slightly rearwards (except the Fastback models) and
lifting it clear.
Before filling fresh oil, run the engine for three to four
minutes to return excess oil from the crankcase, observ-
ing the oil circulating through the oil tank filler orifice.
Allow the oil to settle in the tank, then fill sufficient oil
of a recommended grade until the correct oil level is
shown on the dipstick. The oil level should not exceed
the “H” mark or fall below the “L” on the dipstick. It is
most important not to exceed the “H” to prevent oil
overflowing into the air filter, causing high oil consump-
tion.
ы „2 № Ди E
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HEN &lt; CHAIN
ADJUSTER
Fig. K2 Oil tank filter and drain plug
SECTION K5
ENGINE OIL CHANGING
Remove the rider's seat, where applicable take out the
two right side cover top fixing bolts, and lift the cover
clear at the bottom rubber mounting. Drain the oil from
the tank by removing the oil tank drain plug, where fitted,
(see Fig. K2, item A) or on earlier models by taking out
the oil filter union securing the oil pipe (see Fig. K3).
This should be carried out when the oil is warm so that
it flows more freely from the tank. The crankcase drain
plug (see Fig. K4, item A) should be removed and the
small amount of oil in the sump allowed to drain off.
Clean the filter on 850 and remove and clean the
adjacent magnetic plug.
The 850 and earlier 750 type of filter can be dis-
mantied for cleaning as shown in Fig. K5.
&copy; 7 Le
[В | FILTER UNION
N Mou
Fig. K3 1970 “S” Roadster oil tank unions
Replace the oil tank and crankcase drain plug or on
earlier models the oil filter and oil pipe. Fill the tank to
the dip stick level with fresh oil and run the engine at a
steady speed to check the oil circulation. The oil level
should not exceed the “H” mark or fall below the “L”
on the dipstick. |
As the oil in the sump has been drain &Agrave;
or two will elapse before the scavenge Si Bfithe pump
begins to return the oil to the tank. Run the engine for
Routine Maintenance
CRANKCASE GAUZE
STRAINER (B)
Fig. K4 Crankcase strainer and drain plug.
three minutes, then stop the engine and allow the oil to
settle in the tank for a further two minutes. Recheck the
oil level and top up as required. Finally, refit the side
panel (where applicable).
A coarse mesh metal filter is incorporated with the oil
feed pipe fixing bolt. This should be cleaned at 2,500
miles intervals — and when the oil is changed.
Fig. Kb Crankcase gauze strainer (all modeis except 1972/73
750 cc)
On late models equipped with the cartridge type oil filter
as shown shaded in Fig. K7, the filter must be changed
at this stage. It will be seen that the filter is located
behind the gearbox between the Isolastic mounting
plates. The filter is of the spin on type. It is prevented
from rotating loose by a retaining strip and screw clip.
To change the filter, remove the screw clip, place an oil
drain trip under the filter and unscrew. it is unusual for
the element to require much effort to turn it free but
— GEARBOX
&gt; LEVEL PLUG (B)
a TT
Fig. K6 Gearbox drain and level plugs
this operation can be aided by the use of a strap wrench.
If for any reason the filter remains immovable and since
It is in any case scrap, it can be removed by piercing
with a large screwdriver or similar implement and using
the screwdriver as a lever to turn the filter free. Remove
the filter and old sealing ring. Moisten the new sealing
ring with oil and install the new filter hand tight only.
Fig. K7 Cartridge type oil filter location
=
”
No
Fig. K8
Routine Maintenance
Replace and tighten the screw clip sufficiently tightly
to prevent the element turning. Do not overtighten
since this may crush the filter.
SECTION K6
GEARBOX OIL LEVEL
An oil level plug is fitted in the gearbox cover (see Fig.
K6).
To check level, remove plug (see F/g. K6, item B)
whereupon oil should seep gently out if level is correct.
If topping up is necessary, remove the filler cap (see
Fig. K6, item C) and repienish with correct grade of oil
until the oil begins to seep from the level plug orifice.
Replace the filler cap and the level plug.
SECTION K7
GEARBOX OIL CHANGING
The gearbox oil should be changed after a run so that
the warm oil flows more freely. (see Fig. K6). Remove
the filler cap and drain plug (A) and drain the oil into a
suitable container. Replace the drain plug and fill the
gearbox through the filler cap orifice (C). Allow time
for oil to pass through the inner cover into the shell.
When the level plug is removed, oil should run from the
level plug hole (B). Allow the surplus oil to drain off and
replace the level plug and filler cap. If this method is not
followed a false level indication will be gained.
CHAINCASE OIL LEVEL
PLUG ORIFICE B ;
Primary chaincase plugs
SECTION K8
PRIMARY CHAINCASE LEVEL
An oil level plug is fitted in the primary chaincase outer
cover. (See Fig. K8). To check level, remove plug (see
Fig. K8, item B) whereupon oil should seep gently out
if correct. If topping up is necessary, remove the filler
cap (see Fig. K8, item.C) and replenish with correct
grade of oil until the oil begins.to seep from the level
plug orifice. Replace the filler cap and the level plug.
Note: under no circumstances allow more than 7fl. oz.
(200 cc) of oil in primary case.
SECTION K9
PRIMARY CHAINCASE OIL CHANGING
Remove the footrest and place a metal tray under the
chaincase. Unscrew the central fixing bolt (see
Fig. K8) and break the joint to allow the oil to drain into
the tray. Wash out the case with clean kerosene
(paraffin). Refit the outer case and remove the filler cap,
and level plug (B). Pour fresh oil into the filler cap
orifice (C) until jt begins to run from the level plug hole.
Allow the surplus to drain off and refit the level plug
and filter cap. Refit the footrest.
SECTION K10
SWINGING ARM PIVOT LUBRICATION
For lubrication purposes, a grease nipple (D) is used on
the plate covering the right side of the swinging arm
bush housing. |
To maintain the oii content, use a grease gun filled
with S.A.E. 140 oil and inject oil sufficient to fill the
cavity every 5,000 miles, alternatively, remove the oil
nippie and fill with an oil gun. It is important to check
that the cavity is filled. The only means of checking is to
remove the spindle locating bolt (see in Fig. F9) and
fill until oil. runs from the hole. Refit the bolt.
SECTION K11
FRONT FORK OIL CHANGING
Under normal conditions the front forks will require no
servicing other thar: an occasional change of oil. Should
the oil level become low it will be indicated by excess
movement of the forks, but only after considerable
mileage. |
Each fork leg is provided with a drain screw (see Fig.
G5) and each leg should be treated separately. Remove
the drain screw, take care not to lose the small fibre
sealing washer. Take the machine off the stand, apply
the front brake and move the forks up and down to
К
к
&gt;
&quot;
Routine Maintenance
expel the oil. Allow a few minutes for draining and repeat
the operation with the other leg. Whiist draining the
right fork leg, the forks should be turned on full right
lock, and conversely for draining the left fork leg.
Refit the drain screws, place the machine on the
centre stand. Remove handlebars to improve accessi-
bility.
Unscrew the large filler r'ug at the top of each leg,
remove the speedometer and tachometer and lift the
front wheel to expose the springs.
Support the wheel with a block of wood to hold the
springs clear. Using two spanners, unscrew the filler
plugs from the damper rods.
Remove the wooden block and allow the forks to
extend fully. Pour in a measured 150 cc (5 fl. oz.) of
oil into each ieg (see Fig. K9). Because of the springs
inside the main tubes the oil will be slow to run down.
Cover the top of the tube with the hand and “pump”
the fork up and down to assist filling.
Expose the springs again and before refitting the filler
plugs to ihe damper rods ensure that their locknuts are
screwed down to the bottom end of the thread on the
rod. Lock the filier plugs and locknuts together then
screw in and tighten the filler plugs.
/
a Ble
Aa
+ 2, A
a A +
.. AS
u 7 FE “ =
Loon E
K
SECTION K12
CHECKING HYDRAULIC BRAKE FLUID
LEVEL (Optional disc brake)
The disc brake is hydraulically operated. Before taking
the motorcycle on the road from new or after attention
to the disc brake, ensure that the master cylinder
reservoir contains the correct amount of fluid.
The master cylinder contains a flexible bellows seal
which fits into the reservoir over the fluid. DO NOT
FILL THIS. Lift the bellows out (see Fig. K10) and lay
on the upturned cap so that dirt does not adhere.
Check that the fluid is to a level of 4 in. (12:9 mm)
from the top of the reservoir and if necessary, correct the
level using the recommended hydraulic fluid. Replace
the bellows seal closed end downwards then refit the
cap tightly.
“ Hvdraulic brake fluid absorbs moisture and it is most
important to keep the cap on tight and also to store the
fluid only in sealed containers. The breather hole in the
cap must be kept clear and no dirt or foreign matter
must be allowed to enter the system.
Important: Hydraulic brake fluid must be handled with
care as it will attack paintwork and certain types of
rubber and plastic.
Fig. K10 Checking master cylinder hydraulic fluid level
=
pr
y”
”
- Routine Maintenance
SECTION K13
CHECKING BATTERY ELECTROLYTE LEVEL
For access to the battery remove the L.H. accessory
cover by turning the ring above the ignition switch to
remove the Dzus fastener. The cover is then lifted out at
the front and clear of the rear pegs. To remove the
battery lift the metal loop of the rubber strap clear of the
battery retaining bar. Disconnect the red ground lead
from terminal “+” and the blue/brown lead from ter-
minal “—” on the battery. Slide the vent pipe clear. Lift
the battery clear, taking care not to spill acid. The electro-
lyte level is embossed on the battery case, visible on the
left side of the battery casing (see Fig. K11). At two
weeks intervals, more frequently in hot climates,the level
of the electrolyte should be checked. If necessary, add
distilled water to maintain the level indicated on the side
of the transparent battery case. Do not use tap water as
this may contain impurities harmful to the battery. Never
use a naked light when examining the cells. (See Fig.
K11).
— If the machine is to be out of use for a lengthy period,
have the battery fully charged and give it a short
refreshing charge at 1 ampere about every two weeks.
This will suffice to keep the battery in serviceable condi-
tion. When the battery is fully charged, the specific
gravity of the electrolyte should be 1-270/1-290 at
60&deg;F (16&deg;C).
Fig. K11
Battery electrolyte level mark (illustrated — Lucas
battery)
K
SECTION K14
SPARK PLUGS
It is most important to use the correct grade of spark
plug, as a spark plug with a low heat factor can cause
pre-ignition and subsequent damage to the engine.
The Champion N7Y is recommended for both Com-
mando and Combat engines and supersedes the N6Y
type previously recommended.
To avoid damage to the insulator, use the plug
spanner provided in the tool kit to remove and refit the
spark plug, which should be firmly tightened to ensure a
gas tight joint.
To adjust or reset the spark plug gap, this is affected
by bending the earth, or side wire, which is ductile. Do
not attempt to bend the centre electrode. The correct
plug gap is 0:023 in. to 0:028 in. (0:59 mm to 0:72 mm).
Before refitting the plugs, see that the sealing
washers are sound, and clean the threads of the spark
plug body.
A smear of graphite grease applied to the threads of
the plug will assist in subsequent removal.
SECTION K15
TIRE PRESSURES
Two different types of tyres, Dunlop K.81 (TT100) and
Avon “GP” tyres, are used, in pairs, on Commando
models. Although these tyres differ in detail, both
require that tyre pressures be varied to cope with
changes in the loading of the motorcycle.
The following chart lists approved tyre pressures
corresponding to loads.
Routine Maintenance
Ib/sq.in. Kg/sq.cm.
Commando with one 168 Ib.
(76-2 Kg) rider: Front 22 1-547
Rear 24 1-687
Commando with two 168 Ib.
(76-2 Kg) riders: Front 24 1-687 -
Rear 28 1-969
Commando with two 168 Ib.
(76-2 Kg) riders and pannier
luggage up to 100 Ib.
(45-36 Kg) : Front 28 1-969
Rear 32 2:250
SECTION K16
ADJUSTING CAM TIMING CHAIN
It is found that slackness of the cam chain can result in
snatch, jarring shocks being delivered to the contact
breaker and auto advance mechanism. This causes
premature wear on these parts. We specify that the
chain tension should be checked at 5000 mile intervals
but, naturally, any obvious slackness evidenced by
noise in this area should be taken up, irrespective of
mileage. Adjust the cam chain tension to between Zin.
and +% in. slack (that is, up to down movement) on the
top run of the chain. To do this necessitates removal of
the contact breaker and auto advance mechanism (use
the withdrawal tool 064298 for the auto advance
cam). Next take off the timing cover, and the cam chain
and slipper tensioner are exposed. The oilway exposed
by removal of the cover must be blocked to prevent the
loss of oil. Note that chain tension can only be adjusted
correctly if there is no play in the intermediate spindle.
~ To check the chain tension, remove the sparking plugs
so that the engine will turn easily and use a + in.
Whit. socket or ring spanner on the camshaft sprocket
nut and turn slowly anti-clockwise so that the lower run
of the chain will be kept tight on the slipper and a true
check of the tension can be made on the top run.
In this way the spanner will control the alternating
oad of the valve springs on the camshaft and it will be
easy to find any tight spot to which the tension should
be adjusted as described.
To increase chain tension, slacken the two nuts
securing the slipper and lift it a little at a time, checking
at each stage after nipping up the nuts whether the
tension is correct. When the correct tension is achieved
secure the slipper nuts to 180 Ib. in (15 Ib. ft.).
It is most importar:* &laquo;hen refitting the timing cover to
~ use the camshaft oil seal guide 06-1359 to avoid
damage to the seal ir the timing cover.
K _
Frindsbury House
Cox Lane
Detling
Maidstone
Kent ME14 3HE
TEL-0622 720553 7&deg;
CL&Eacute; FAX:0622 720931
'BOYER BRANSDEN ELECTRONICS LTD
ROYER BRANSDEN ELECTRONIC IGNITION SYSTEM FOR NORTON COMMANDO - TYPE MK 3
Comprising: | d) Plastic strap
n) Transistor hox (square black box with wires) e) ie x 1&quot; BSF bol.
Hh) Stator Plate (round printed circuit with two coils and connection block) f) Instruction sheet
c} Magnetic rotor (round plated steel unit with two square magnets fitted) '
FITTING INSTRUCTIONS
Fig 1
1) Remove seat,
2) Remove tank, disconnect fuel lines.
3) Remove contact breaker cover.
4) Remove contact breaker assembly complete including the auto-advance
unit. Disconnect the two wires black white and black yellow,
5) Set engine at 31 B, T. D.C. on the alternator mark {ensure correct mark or on
is used - there are two marks on the alternator on 1972/3 models, use = — —
the mark indicating T.D. C. with the pistons in top position).
6) Fit magnetic rotor unit using the short bolt supplied, with the magnets
in line with the name Norton on the timing case. See fig 1.
7) Fit stator plate with the connecter block at the bottom using the standard studs.
8) The magnet on one side of the rotor should now be in the centre of the top
timing hole in the stator plate with it adjusted half way along its adjustment
slots. If not move rotor until this is so without turning the engine from 31 B.T.D.C. See fig 2.
9} Connect the two wires in the timing cover to the black connector block (black
white to silver unmarked terminal and black yellow to terminal marked with
yellow),
10) The two wires in the timing cover can be traced up the frame tube to a
pair of bullet type connectors, remove these leaving the connectors on
the wires going down to the timing cover. ; +
il) Remove all the low tension connections from the two ignftion coils,
12) Remove the white blue wire from the ballast resistor between the two
ipnition coils, q
Fig 2
Orion)
; CH 1 eee
raed 13) Remove the red wire from ita earthing point on the an af = andensor Faasle Timing FT A
to Tm a pack. Reconnect this gh the + marked terminal on the left hand ignition coil. ое
14) Fit transistor box to me tube with plastic strap. See fig 3, with the
long wires to the right hand front side and the two short wires to the left,
15) Connect short black white and black yellow wires from transistor box
to the two wires which feed down to the timing cover, using the bullet connectors.
16) Connect the red wire from transistor box first connector to the earth tag on the end of +
the condensor pack and the second connector to the + terminal of the left hand ignition
coil with the red wire already connected to it,
17) Connect the - terminal of the left ignition coil to the + of the right hand coil using the
short hlack connecting wire, ‘
18) Connect the - terminal of the right hand coil to the black wire from the transistor box.
19) Connect the white blue wire (this was the one removed from the ballast resistor)
to the white wire from the transistor box.
20) All original wires that have been rermved are now not in circuit and can
Fig. 3
x
be safely tucked out of the way. ue Y
21) Check all connections are good and tight, if not remove and tighten with
pliers,
22) Refit tank fuel lines and seat,
23) Start engifie and time with a stroboscope to 31 B.T.D.C. with the engine
running in excess of 5000 r.p.m. Thin is done by moving the generator Transistor
stator plate. If the timing is not obtainable before the end of the adjust. Box
= ment the magnetic rotor will have to be slackened off and moved a small
White White Blue
amount until the timing can be obtained. 8 T be
21) Refit timing cover. | Frome Tu
+ .
’ | Se
+
A
From Ignition Switch - 12V
(White on Pre 71 Models)
Black
, BY - 4 Black Yellow
BW Black White
Transistor
+
Brix
Circuit diagram
Red
=
X
Е
For pre 1971 models the white wire from the
Stator Plate transistor box connects to one of the double
white wires removed from the ignition coils.
e Tape up spare white wire to avoid it shorting
| Lett Hand Right Hand
; ВЕ to chassis,
1 Cnil Coil
INT A Chasse
ed
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Key features

850cc engine for ample power.
Robust chassis for handling various terrain.
Comfortable seat for extended rides.
Responsive suspension system for a smooth ride.
User-friendly controls for ease of use.

Frequently asked questions

850cc

Both on- and off-road

Yes, it has a comfortable seat and a responsive suspension system.

What is the engine capacity of the Norton Commando 850?

What type of terrain can the Norton Commando 850 handle?

Is the Norton Commando 850 comfortable to ride?

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