User manual | HUSQVARNA

CHAIN SAW
HUSQVARNA
HUSQVARNA
Model
Bore
mm (in.)
40 Rancher, 140S, 240 S,
240 SE, 240 SG, 340 SE,
340 SG
40.0
(1.575)
44, 44 CB, 44 Rancher, 444 CB,
444 SE, 444 SG
42
(1.654)
MAINTENANCE
SPARK PLUG. Recommended spark
plu^ is CdamfHon RCJ7Y. Spark plu^
electrode gap sfiouUi be 0.5 mm (0.020
in.).
CARBURETOR. Late Model 44 is
equipped witfi a Walhro Model HDA
(liafjhra^tn carburetor. All other models
are e(|uipf)ed with a Walbro Model HDC
carlmretor. Refer to CARBURETOR
SKRVK'E section tor carburetor service and exploded view.
On 14{)S models equipped witli Watbro
HI)(' 10 carburetors, initial setting- of
low speed mixture screw is ^A turn open
while initial setting of higli sf)eed mixture screw is V2 turn o[)en. Initial setting
for late Mociel 44 with Wall)ro Model
HDA carburetor is IV4 turns ()i:)en for
low and high speed mixture screws. Initial setting for all other mociels is one
turn oj)en for low speed and high speeci
mixture screws.
On ail models, make final adjustment
with engine warm and running. Adjust
idle speed screw so engine idles just
below clutch engagement speed. Adjust
low speed mixture screw so engine will
accelerate cleanly without hesitation.
Fig. HIO—Distance (D) from flywheei mark to
edge of coii leg shouid be 2.5 mm (0.1 In.} when
breaker-points open.
240
Stroke
mm (in.)
Displacement
cc (cu. in.)
Drive
32.0
(1.26)
40.0
(2.4)
Direct
32
44
Direct
(1.26)
(2.7)
Adiust hi^h sc»eed mixture screw to obtain optimum performance under cutting load.
Note that intake manifold must be installed with oval opening next to
cylinder and round opening next to carburetor.
IGNITION. Models 40 Rancher, 140S
and 240S are equipped with a breakerpoint type flywheel magneto ignition
system. Air gap between flywheel and
coil legs should be 0.30-0.35 mm
(0.012-0.014 in.). Breaker-point gap
should be 0.3-0.4 mm (0.012-0.016 in.).
Breaker-points should begin to open
when mark on flywheel is 2.5 mm (0.1
in.) from upper edge of lower coil leg as
shown in Fig. HIO. Use a suitable test
light or continuity meter to check
breaker-point opening.
Models 240SE, 240SG, 340SE and
340SG are equipped with a two-piece
breakerless electronic ignition system.
An ignition module (6-Fig. Hll) is
Fig. HII — Expioded view of eiectronic ignition
system used on Models 240SE, 240SG, 340SE
and 340SG, Generating coU (3} is used on Modeis
240SG and 340SG with heated handles.
1. "O" ring
2. Seal retainer
3. Generating coil
4. Flywheel
5. Ignition eoil
6. Ignition module
Type
located in the rev
Models 44, 444SE and 444SG are
equipped with a one-piece breakerless
electronic ignition system. Air gap on
both types of breakerless ignition
systems, between flywheel and coil legs,
should be 0.30-0.35 mm (0.012-0.014 in.).
On all models, flywheel may have two
crankshaft key grooves. Key groove
marked "P" is used on models equipped
with Prufrex ignition systems while the
Fig. Hi2 —Exploded view of engine. OH pump
drive gear (8) is used on Modeis 140S, 240S,
240SE and 240SG. Note oii pump gear In Fig.
H17 used on aii other modeis.
1.
2.
3.
4.
5.
6.
Air baffle
Intake manifold
Cylinder
Piston ring
Piston & pin
Pin retainer
7.
8.
9.
10.
Bearing
Oil pump drive gear
Bearing
Crankshaft & rod
assy.
IHustrations courtesy Husqvama Forest & Garden Co.
SERVICE MANUAL
other key groove is used on models
equipped with Bosch and breaker-point
ignition systems. Tighten flywheel nut
to 23.5-28.4 N-m (17-21 ft.lbs.).
LUBRICATION. Recommended
fuel:oil ratio for engine lubrication is
50:1 when using Husqvarna Two-Stroke
Oil, If Husqvarna Two-Stroke Oil is not
available, fuehoil ratio should be 25:1 using a good quality oil designed for use in
two-stroke air-cooled engines.
The chain is lubricated by oil from an
automatic chain oil purnp. Clean automotive oil may be used. Oil viscosity
should be chosen according to ambient
temperature. Oil may bs cut with up to
50 percent kerosene in extremely cold
weather.
Oil pump output oa 140S, 240S,
240SE and 240SG is not adjustable. Oil
pump output on all other models is adjusted by exchanging 2am screw ( 2 Fig. HI7). Cam screw is available from
the manufacturer in three color-coded
sizes, A white cam scre^v indicates minimum oil output, a plain cam screw indicates standard oil output while a green
cam screw indicates maximum oil output. Refer to OIL PUMP section for
replacement procedure.
REPAIRS
CYLINDER, PISTON, PIN AND
RINGS. Cylinder has a chrome bore
which should be inspected for flaking,
HUSQVARNA
cracking or other damage to chromed
surface. Some pistons are equipped with
one piston ring while others are
equipped with two piston rings. Piston
ring groove has a locating pin to prevent
piston ring rotation. Arrow on piston
crown must point toward exhaust port
when installing piston.
Piston and cylinder are graded according to size to provide correct piston-tocylinder clearance. Piston and cylinder
bore sizes are indicated by a letter
stamped on the piston crown or on the
top of the cylinder. See Fig, H13. If cylinder is new or has very little use, piston
and cylinder grade should be the same.
If cylinder is used but not excessively
worn, a piston with the same grade or a
piston with the next largest grade may
be installed. For instance, pistons with
grade letters "B"or "C" may be installed
in a used cylinder with grade letter "B."
Grade letter "A" denotes smallest cylinder or piston while grade letter "E"
denotes largest cylinder or piston.
Tighten cylinder base screws to 8,8-9,8
N-m (78-87 in.-lbs.)
Illustrations courtesy Husqvarna Fores: & Garden Co.
AUTOMATIC OIL PUMP. Models
140S, 240S, 240SE and 240SG are
equipped with the automatic oil pump
shown in Fig. H15 and Fig. H16. Oil
pump output is not adjustable. Access to
oil pump components is obtained after
removing guide bar plate (8-Fig. HI5).
Withdraw pin (14), unscrew plug (12)
and withdraw plunger (15). Oil pump is
CRANKSHAFT, CONNECTING ROD
AND CRANKCASE. Crankshaft and
connecting rod are a unit assembly. It
will be necessary to heat crankcase
halves to remove or install crankshaft
and main bearings. Care should be taken
not to damage mating surfaces of crankcase halves. Check rotation of connecting rod around crankpin and renew
crankshaft unit if roughness or other
damage is found.
When reassembling crankshaft and
crankcase halves, install main bearings
allowing for installation of oil pump on
drive side and crankshaft seal housing
on flywheel side. A special tool is available from the manufacturer to properly
position main bearings and crankshaft in
crankcase. Tighten crankcase screws to
7-8 N-m (61-69 in.-lbs.). Make certain
crankshaft is centered in crankcase and
will rotate freely.
Fig. HU-Expioded
Fig. Hta-'View showing iocation of cylinder
and piston grade ietters. Grade "D"* is shown.
CLUTCH. All models are equipped
with the two-shoe centrifugal clutch
shown in Fig. H14. Clutch hub (1) has
left hand threads. Inspect clutch shoes
and drum for excessive wear or damage
due to overheating. Clean and inspect
clutch hub, drum and bearing for
damage or excessive wear. Inspect
clutch bearing lubrication hole in crankshaft end and clutch bearing contact surface on crankshaft for wear or damage.
1. Clutch hub & shoes
2. Clutch drum
3. Bearing
view of clutch.
4. Sprocket
5. Washer
12
Fig. HIS-Expioded view of eariy oii pump
assembiy.
7.
8.
9.
10.
11.
12.
13.
Oil seal
Bar plate
Gasket
Washers
Oil pump gear
Plug
Washer
14.
15.
16.
17.
18.
19.
20.
Pin
Plunger
Dowel pin
Right crankcase half
Screen
Spring
Plug
15 14 12
Fig. HH~ View of oil pump components. Pin (14)
is iocated in hoie m Refer to Fig. HfS for parts
identification.
241
HUSQVARNA
CHAIN SAW
Fig. H19A-Exploded view
of typical chain brake used
on later models. Some
models may have adjustable
type brake band shown In inset.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
U.
12.
13.
14.
14
Hand guard
Cap screw
Trunnion
Trigger button
Trigger lever
Pin
Spring
Nut
Latch
Spring
Housing
Guide
Brake band
Chain guard
Fig. HU--Exploded view of oil pump used on
Models 40 Rancher, 44, 340SE, 340SG, 444SE
and 444SG.
1.
2.
3.
4.
5.
PluK
Cam screw
FMug
Pump bt)dy
Tube
6.
7.
8.
9.
10.
Seal
Drive gear
Spring
Washers
Plunger
driven by gear (8-Fig. H12) on crankshaft. A special tool is available from the
manufacturer so gear can be removed
without removing crankshaft.
Automatic oil pump used on all other
models is shown in Fig. H17. Oil pump
output is adjusted by exchanging cam
screw (2-Fig. HI7). Cam screw is available from the manufacturer in three
color-coded sizes. A white cam screw indicates minimum oil output, a plain cam
screw indicates standard oil output
while a green cam screw indicates maximum oil output. Remove clutch for access to oil pump. Unscrew cam screw (2)
before withdrawing pump plunger (10).
Pump plunger (10) is driven by worm
gear (7) on crankshaft. A special tool is
available from the manufacturer for
worm gear removal. Collar on worm
gear must be toward oil pump when installed.
REWIND STARTER. To disassem
ble rewind starter on all models, first
remove starter housing from saw. Pull
starter rope and hold rope pulley with
IfFig. H19~Turn screw (S) to adjust chain brake
on early models. Refer to text
Fig. H18-Exploded view of
Models 40 Rancher and 44
rewind starter. Other models
are similar.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
242
Flywheel
Pawl stud
Spring
Paw!
Clip
Screw
Rope pulley
Rope guide
Rewind spring
Washer
Starter housing
notch in pulley adjacent to rope outlet.
Pull rope back through outlet so it engages notch in pulley and allow pulley to
completely unwind. Unscrew pulley retaining screw (6-Fig. H18) and carefully remove rope pulley. If rewind
spring must be removed, care should be
taken not to allow spring to uncoil uncontrolled.
Install rewind spring in starter housing with spring coiled in clockwise direction from outer spring end. Wrap
starter rope around rope pulley in a
clockwise direction as viewed with
pulley in starter housing. Turn rope
pulley two turns clockwise before passing rope through rope outlet to place
tension on rewind spring. Spring tension
is correct if rope pulley can be rotated at
least V2 turn further when rope is pulled
completely out.
When installing starter assembly on
saw, make sure starter pulley properly
engages pawls on fljrwheel before tightening retaining cap screws.
CHAIN BRAKE. Some models may
be equipped with a chain brake system
designed to stop chain movement should
kickback occur. Several types of chain
brake systems have been used.
The chain brake on early models is activated when the operator's hand strikes
the hand guard. To adjust chain brake
on early models, pull back hand guard
and be sure mechanism is cocked. Turn
adjusting screw (S-Fig. H19) in until
chain cannot be pulled around bar then
turn screw out three or four turns. If
screw has a square head, be sure screw
head does not rest on side plates (P).
The chain brake on later models is activated either by the operator's hand
striking the hand guard (1-Fig. H19A)
or by sufficient force being applied to
the guide bar tip during kickback to
cause the front handle to contact the
trigger button (4) resulting in automatic
Illustrations courtesy Husqvama Forest & Garden Co.
SERVICE MANUAL
activation of brake mechanism. To adjust chain brake on later models, first
pull back hand guard and be sure
mechanism is cocked then determine if
brake system has an adjustable brake
band as shown in inset of Fig. H19A. If
brake band is adjustable, turn adjusting
screw (S) in until chain cannot be pulled
Illustrations courtesy Husqvarna Foftst tic Garden Co.
HUSQVARNA
around bar then turn screw out three or
four turns. Chain should rotate freely
around bar. Check brake band tension
adjustment by starting saw and running
at wide open throttle, then manually
engage chain brake. Chain should stop
rotating immediately. On models without adjustable brake band, be sure
spring retaining nut (8) is tight against
its seat. On all models, gap between trigger button (4) and front handle should be
adjusted so chain brake will automatically activate when a 6.2-9.8 N (1.4-2.2 lbs.)
force is applied on guide bar tip. A
suitable spring balance should be used
for testing and adjustment.

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