Sherco Engine Teardown and Assembly Manual
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Sherco Engine Teardown and Assembly Manual
This Manual is provided as a guide for:
• Removing the engine from the frame
• Splitting the cases
• Complete Disassembly of the engine
• Reassembly of the engine
• Reinstallation back in the frame
The text and pictures in this manual were provided by a Team Sherco Rider who
recorded the process as he performed these operations on a 2001, 2.9.
For additional information see the following manuals that can be downloaded from
the www.shercousa.com and the www.sherco-moto.com sites.
• Water Pump Seal Replacement
• Sherco Ignition Timing Guide
• Sherco Setup and Lubrication Guide
• Sherco Top End Maintenance Manual
• Sherco Bike Assembly Manual
If you have any questions about the procedure please call Ryan
Young Products at 1-800-607-8742.
By Bill Ibsen 3/03
4/11/2003
Sherco Engine Teardown
and Assembly Manual
1
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Engine Removal and Case Splitting
Preparation
1. Wash the bike and engine thoroughly.
2. Drain transmission oil by removing drain bolt and copper washer with 5mm Allen.
3. Drain coolant by removing 3 bolts of water pump cover and lifting off engine side case.
4. Remove:
a. rear fender- two bolts plus one long with washer using 4mm Allen
b. fuel tank hose from petcock
c. fuel tank- one short bolt and washer using 4mm Allen
d. chain master link and chain from front sprocket
e. kick starter- one large button head bolt and washer
f. rear brake- one bolt/washer using 13mm wrench
g. rear brake master cylinder- 2 button head bolts
h. gear shifter- one bolt
i. flywheel cover – 3 bolts
j. clutch slave cylinder- two button head bolts using 4mm Allen
k. clutch actuating rod by pulling it out of the case
l. airbox three 4mm Allen bolts and loosening Phillips head carb hose clamp
m. carburetor cap/slide assembly
n. carburetor by loosening Phillips head manifold hose clamp
o. spark plug cap
p. spark plug
q. header pipe 2 bolts into cylinder head
r. silencer- 3 bolts (one with washer and nut using 10mm wrench)
s. cylinder head coolant hose clamp and hose
t. rear shock upper bolt
u. radiator plastic cover bolt, then lever up the radiator with screwdriver until
the radiator “legs” pop out of frame retaining holes
5. Remove flywheel using flywheel puller tool, taking care not to lose the small Woodruff
key by placing it inside of the magnetic flywheel for safe storage.
6. Remove ignition (3 bolts) and slide rubber grommet and ignition wiring assembly out
of the case and out of the way, taking special note of the ignition timing marks.
7. Remove front sprocket and 2 retaining circlips.
8. Remove clutch side case and its 10 bolts using 5mm Allen, being careful not to lose to
lose the 2 aluminum alignment pins (dowel pins). Insert the dowel pins into their holes
within the Right Crankcase.
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and Assembly Manual
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9. Remove water pump impeller using 12mm long socket Remove water pump axle,
taking care not to lose the washer between the case and the impeller axle inspect
axle and seals for damage (scratches) and wear.
10. Remove 6 ea. clutch 8mm bolts/washers/springs. Check the clutch springs for
fatigue and replace them if necessary.
11. Remove clutch pressure plate and inspect each friction disc for burning, wear, or
any other damage, and replace damaged discs. Check the clutch metal plates for
face runout. Warped or damaged plates may cause the clutch to slip when
engaged.
12. Remove crankshaft primary gear nut and washer using 19mm socket, holding
clutch basket with special clutch basket tool.
13. Remove clutch outer basket nut and washer with 24mm socket while holding the
basket with special clutch basket holder tool. Check the clutch outer basket for
stepping and replace it if necessary.
14. Remove crankshaft primary gear and tiny Woodruff key, being careful not to lose
the key.
Engine Removal from Frame
1. Remove shock top mounting bolt, nut, and washer using 17mm wrench and Allen,
then slide the shock out of the sub-frame shock mounting bracket.
2. Remove top cylinder head “U” shaped bracket assembly (bolt, washer, nut) and
frame bolts.
3. Remove two front skid plate frame bolts and nuts.
4. Loosen front engine/frame bolt and nut.
5. Remove swingarm axle/bolt black covers by prying them off.
6. Loosen swingarm “axle” and nut.
7. Loosen bottom engine bolt and nut.
8. Remove front engine/frame bolt and nut and other engine/frame/swingarm bolts.
9. Wiggle/pull swingarm assembly away from engine mounts to allow space for
engine removal.
10. Rotate engine upwards, then swing rear towards rear brake, and twist engine out of
frame on throttle side of frame.
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and Assembly Manual
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Engine Disassembly
1.
2.
3.
4.
5.
6.
7.
Pinch front engine Crankcase mounting ears into a vise to hold engine stable and upright.
Remove 4 bolts (with 4mm Allen) and pull out rubber carburetor manifold.
Remove reed valve cage (just pull it out of cases by hand)
Remove 4 cylinder head base nuts with 13 mm wrench
Remove cylinder and cylinder head assembly as a single unit.
Place a clean cloth over the bore in the crankcase.
Remove piston by removing one circlip, then pushing/tapping the wrist pin & wrist pin
bearing cage out enough to remove it from the connecting rod.
8. Inspect the piston, piston rings, and cylinder for wear, damage, or sticking rings.
9. Decarbonize piston head with razor edge, noting whether its an A, B, or C size piston.
10. Decarbonize cylinder head and exhaust port using a scraper of soft material such as wood
or plastic to prevent damage to the parts. Carbon deposit build up will decrease engine
performance.
11. Remove/replace new rings, installing new rings with machined “dot” marking facing
upwards. Place the rings in the ring grooves and turn the rings to check for smooth
movement. Decarbonize the ring grooves if necessary. Note: Discard the piston pin clip
removed. Use a new clip.
12. Check crankshaft bearings by alternately pulling up and down on the crankshaft ends. If
free-play exists, then replace the crankshaft main bearings and seals housed inside the
center cases.
13. Press in the ratchet pawl spring assembly to release it from the “wheel carousel” and pull
the gear shift axle assembly through the motor and out of the engine.
14. Remove the engine oil drain bolt
15. Remove the four upper, equal length 5mm Allen engine case bolts holding the side cases
together. 2 are located at the intake manifold, and the other 2 are located at the top and
bottom of the front sprocket.
16. Remove another longer 5mm Allen engine case bolt located on the topside of the case,
utilizing the aluminum case alignment pin, furthest back on the case towards the swing arm.
17. Remove the five 5mm Allen crankcase bolts located behind the flywheel.
18. Lay engine on a pile of rags on the floor, and holding one of the side cases, using a rubber
mallet split the cases, alternating soft blows on one end of the case to another.
19. When the cases are split about an inch, lay it on the clutch side and alternate blows to the
crankshaft and gear axle to carefully and slowly remove the cases, ensuring that the gear
drum and two gear assemblies do not fall out or get dislodged. (A long rubber band can be
used to hold the transmission in place during handling). Be careful not to lose the two
thin washers at the ends of the adjacent transmission shafts.
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and Assembly Manual
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Engine Disassembly Contd.
20. If not removing the transmission, place a long rubber band around the engine in such a
way to secure the mainshaft and countershaft assemblies from falling out of the Right
Crankcase.
21. Using a screwdriver, push out the crankshaft main bearing seals out of each case side,
and then using a large socket, tap out the main bearing cages.
22. Inspect freeplay and free movement of connecting rod in and around crankshaft lobes. If
a problem exists, a machine shop will be required to press the parts apart and back
together again after repair.
23. With a razor, thoroughly clean off all residue of all gaskets on inside and outsides of
cases and the bottom of the cylinder, but especially around the intake manifold area of
the cases.
24. Using parts washer and contact cleaner on a rag, clean cases
25. Wire brush rusty cylinder studs, spray with WD40
26. Clean all bolts before reinstallation
Reinstallation, General Tips
1. As a general rule, when reassembling any motorcycle, always replace all gaskets,
O-rings, cotter pins, piston pin clips, lock washers, snap rings, etc..
2. When torquing bolts, nuts or screws, start with the larger-diameter or inner fasteners,
and tighten them to the specified torque using a criss-cross (star) pattern.
3. Clean all parts after dismantling, and when reassembling, coat all sliding surfaces
with the same type of lubricant that will be used during the operation of the engine.
4. After reassembling, check to be sure that each part is securely tightened.
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Sherco Engine Teardown
and Assembly Manual
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Reassembly Steps
1. First, install main bearings in cases by placing the clutch side center case with
transmission installed on a rag at an angle, and tap the right crankshaft main bearing
seal with a wooden hammer into the case.
2. Next, install crankshaft assembly into the above assembly, oiling the crankshaft seal
surfaces contacting the crankshaft.
3. Next, install center case gasket, checking multiple times for perfect alignment (not
positioned above or below case edge, but centered on the case edge).
4. Next, install flywheel side center case using 4 or 5 bolts around the perimeter of the
case, tightening them in a criss-cross (star) pattern, while constantly confirming that
perfect gasket alignment between both center cases (especially at intake manifold area).
Do not tighten these first case bolts end to end; use a criss-cross (star) pattern to
progressively and evenly tighten the two center cases together.
5. Reinstall the five flywheel bolts (Step 14 above).
6. In general, reassemble in the reverse order of disassembly, beginning at Step 13 above,
using new gaskets and piston pin clips. Coat the cylinder wall with oil before lowering the
cylinder over the piston, taking care not to damage the cylinder.
7. Install the piston with “=->” arrow mark on the piston crown facing towards exhaust port.
8. When reinstalling the engine within the bike’s frame, place it in the frame sideways at
an angle, then tip the cylinder head upwards while swinging the rear of the motor
around into its mounting position within the frame, and then lower the front of the motor
into its normal mounting position.
9. Regrease the swing arm bolt.
10. Install a new spark plug.
11. Add 450cc of transmission oil and distilled water/coolant mixture to radiator.
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Sherco Engine Teardown
and Assembly Manual
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Pictorial Aid to Frame & Engine
Bolt Identification
Unassembled Engine:
Right Crankcase with Transmission
Left Crankcase
Cylinder Head
Crankshaft
Assembly
Reed Case
Bottom Clutch Cover Assembly
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Sherco Engine Teardown
and Assembly Manual
Piston, Wrist
Pin, Bearing
Intake Manifold
7
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Pictorial Aid to Frame & Engine
Bolt Identification Contd.
Frame:
Front Engine Frame Support
Bolt/Nut
Front Sprocket &
Retaining Circlips
Rear Engine Frame
Support Bolt/Nut
Fuel Tank
Bolt
Swingarm Axle
Rear Fender
Nut Clip
Swingarm Bolt Covers
Rear Fender
Front Bolt
Kickstarter
Water Pump
Cover
Header Pipe
Sparkplug
Ignition
Flywheel
Nut
Front Frame/Skidplate
Bolts/Nuts
Cylinder/Frame Support Bolts
Ignition/Wiring
Harness bolt/Washer
Ignition
Cover
4/11/2003
Airbox
Sherco Engine Teardown
and Assembly Manual
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Internal Engine Components & Bolts
Cylinder Head Nuts
Water Pump Axle, Gear
& Impeller
Engine Oil Drain Bolt/Washer
Crankshaft Main Bearing Seals
Rear-most Upper
Center Case Bolts
Crankshaft Main Bearings
Clutch Side Cover Bolts
Center Case Bolts
Crankshaft Primary
Gear, Key, Washer, Nut
Ignition Center Case
Bolts
Clutch Metal & Friction
Discs
Clutch Rod/Actuator
Piston Circlip
Clutch Springs,
Washers & Bolts
Gearshift Shaft W/Pawl Assembly
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Sherco Engine Teardown
and Assembly Manual
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Clutch Components:
Primary Drive Clutch
Gear/Outer Clutch Basket
& Washer
Clutch Pressure Plate
Clutch Lifter
Rod
Clutch Friction Discs
Clutch Metal Discs
Clutch Thrust Needle
Bearing & Thrust
Washer
Clutch Hub/Inner Basket, Washer, Nut
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and Assembly Manual
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Misc. Parts:
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Large Component Removal
Leave bolts in brake pedal, shift lever, and silencer. Place flywheel/crankshaft Woodruff Key inside magnetic
flywheel for safe storage until reassembly
Frame:
After engine removal with swingarm pulled back.
4/11/2003
Leave bolts in rear brake master cylinder and shock.
Sherco Engine Teardown
and Assembly Manual
11
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Engine Assembly Overview
Cylinder & Cylinder Head
Left Crankcase
Countershaft
Mainshaft
Crankshaft
Shift Forks
Right Crankcase
Gearshift Drum
Gasket Removal
Clean all gasket surfaces using a razor blade.
4/11/2003
Gasket surfaces should be cleaned like new.
Sherco Engine Teardown
and Assembly Manual
12
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Other Details
Ignition:
Piston Markings:
Piston Size A.B.C or D.
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Sherco Engine Teardown
and Assembly Manual
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