engine YAMAHA YZ250LC 2006 Notices Demploi (in French)

4-62
ENGINE REMOVALENG
EC4M3340
Engine removal
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.
1. Lift the engine 1up to the point where the
engine’s mounting front does not contact the
bracket on the frame.
2. Remove the engine 1aslant and upward
while inclining it toward the kick crank side
so that the engine’s mounting top does not
contact the bracket on the frame.
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:
9Nut (drive sprocket) 1
9Lock washer 2
NOTE:
9Straighten the lock washer tab.
9Loosen the nut while applying the rear brake.
2. Remove:
9Drive sprocket 1
9Drive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
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4-63
ENGINE REMOVALENG
EC4M5211
Brake pedal
1. Install:
9Spring 1
9Brake pedal 2
9O-ring 3
9Bolt (brake pedal) 4
9Clip 5
NOTE:
Apply the lithium soap base grease on the bolt,
O-rings and brake pedal bracket.
EC4M5000
ASSEMBLY AND INSTALLATIONEC4M5124
Engine installation
1. Install:
9Engine 1
Install the engine from right side.
9Pivot shaft 2
9Engine mounting bolt (lower) 3
9Engine mounting bolt (front) 4
9Engine bracket 5
9Bolt (engine bracket) 6
9Engine mounting bolt (upper) 7
NOTE:
Apply the molybdenum disulfide grease on the
pivot shaft.
85 Nm (8.5 m•kg, 61 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
26 Nm (2.6 m•kg, 19 ft•lb)
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4-64
ENGINE REMOVALENG
4. Install:
9Chain guide 1
9Chain cover 2
9Screw (chain cover) 3 2. Install:
9Lock washer 1
9Nut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
3. Bend the lock washer tab to lock the nut.
5 Nm (0.5 m•kg, 3.6 ft•lb)
75 Nm (7.5 m•kg, 54 ft•lb)
EC4M5341
Drive sprocket
1. Install:
9Drive sprocket 1
9Drive chain 2
NOTE:
Install the drive sprocket together with the drive
chain.
5. Connect: (except for USA and CDN)
9Neutral switch lead
Refer to “CABLE ROUTING DIAGRAM”
section in the CHAPTER 2.
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4-65
CRANKCASE AND CRANKSHAFTENG
EC4N0000
CRANKCASE AND CRANKSHAFT
Extent of removal:1Crankcase separation2Crankshaft removal
3Crankshaft bearing removal
10 Nm (1.0 m•kg, 7.2 ft•lb)30 Nm (3.0 m•kg, 22 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
Extent of removal Order Part name Q’ty Remarks
CRANKCASE AND CRANKSHAFT
REMOVAL
Preparation for Engine Refer to “ENGINE REMOVAL”section.
removal Piston Refer to “
CYLINDER HEAD, CYLINDER
AND PISTON
” section.
Primary drive gear
Kick idle gearRefer to “
KICK AXLE, SHIFT SHAFT AND
Stopper leverPRIMARY DRIVE GEAR”section.
Rotor and stator Refer to “CDI MAGNETO” section.
1 Segment 1 Refer to “REMOVAL POINTS”.
2 Holder 2
Except for USA and CDN
3 Bolt (Neutral switch lead holder) 1
4 Bolt [L=50 mm (1.97 in)] 7
5 Bolt [L=60 mm (2.36 in)] 1
6 Bolt [L=70 mm (2.76 in)] 3
7 Holder 2
8 Crankcase (right) 1 Use special tool.
9 Crankcase (left) 1 Refer to “REMOVAL POINTS”.
10 Crankshaft 1 Use special tool.
Refer to “REMOVAL POINTS”.
11 Oil seal 2
12 Bearing 2 Refer to “REMOVAL POINTS”.




12
3






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4-66
CRANKCASE AND CRANKSHAFTENG
EC4N3212
Crankcase
1. Remove:
9Crankcase (right) 1
Use the crankcase separating tool 2.
NOTE:
9Make appropriate bolts 3as shown available
by yourself and attach the tool with them.
9Fully tighten the tool holding bolts, but make
sure the tool body is parallel with the case. If
necessary, one screw may be backed out
slightly to level tool body.
9As pressure is applied, alternately tap on the
front engine mounting boss and transmission
shafts.
cC
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case. Do
not tap on gasket mating surface. Work
slowly and carefully. Make sure the case
halves separate evenly. If one end “hangs
up”, take pressure off the push screw,
realign, and start over. If the cases do not
separate, check for a remaining case screw
or fitting. Do not force.
EC4N3000
REMOVAL POINTS
Segment
1. Remove:
9Bolt (segment) 1
9Segment 2
NOTE:
Turn the segment counterclockwise until it stops
and loosen the bolt.
cC
If the segment gets an impact, it may be
damaged. Take care not to give an impact
to the segment when removing the bolt.
Crankcase separating tool:
YU-1135-A/90890-01135
1P8-9-31-4C 5/12/05 1:21 PM Page 34

4-67
CRANKCASE AND CRANKSHAFTENG
EC4N4000
INSPECTION
EC4N4101
Crankcase
1. Inspect:
9Contacting surface a
Scratches
Replace.
9Engine mounting boss b, crankcase
Cracks/Damage
Replace.
EC4N3401
Crankshaft bearing
1. Remove:
9Bearing 1
NOTE:
9Remove the bearing from the crankcase by
pressing its inner race as shown in å.
9If the bearing is removed together with the
crankshaft, remove the bearing using a general
bearing puller 2as shown in ∫.
9Do not use the removed bearing.
EC4N3302
Crankshaft
1. Remove:
9Crankshaft 1
Use the crankcase separating tool 2.
NOTE:
Make appropriate bolts 3as shown available by
yourself and attach the tool with them.
cC
Do not use a hammer to drive out the
crankshaft.
Crankcase separating tool:
YU-1135-A/90890-01135
1P8-9-31-4C 5/12/05 1:21 PM Page 36

6. Install:
9Holder (except for USA and CDN) 1
9Bolt [holder (except for USA and CDN)] 2
9Bolt (crankcase)
NOTE:
Tighten the crankcase tightening bolts in stage,
using a crisscross pattern.
4-71
CRANKCASE AND CRANKSHAFTENG
8. Tighten:
9Segment 1
9Bolt (segment) 2
NOTE:
9When installing the segment onto the shift cam
3, align the punch mark awith the dowel pin
b.
9Turn the segment clockwise until it stops and
tighten the bolt.
cC
If the segment gets an impact, it may be
damaged. Take care not to give an impact
to the segment when tightening the bolt.
30 Nm (3.0 m•kg, 22 ft•lb)
7. Install:
9Tension spring 1
9Holder 2
9Bolt (holder) 3
NOTE:
Install the holder so that it contacts the projec-
tion aon the crankcase (right).
10 Nm (1.0 m•kg, 7.2 ft•lb)
9. Remove:
9Sealant
Forced out on the cylinder mating surface.
10. Apply:
9Engine oil
To the crank pin, bearing, oil delivery hole
and connecting rod big end washer.
11. Check:
9Crankshaft and transmission operation
Unsmooth operation
Repair.
14 Nm (1.4 m•kg, 10 ft•lb)
14 Nm (1.4 m•kg, 10 ft•lb)
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4-72
TRANSMISSION, SHIFT CAM AND SHIFT FORKENG
Extent of removal Order Part name Q’ty Remarks
TRANSMISSION, SHIFT CAM AND
SHIFT FORK REMOVAL
Preparation for EngineRefer to “ENGINE REMOVAL” section.
removal Separate the crankcase. Refer to“CRANKCASE AND CRANK
SHAFT
” section.
1 Main axle 1
2 Drive axle 1
3 Shift cam 1
4 Shift fork 3 1Refer to “REMOVAL POINTS”.
5 Shift fork 2 1
6 Shift fork 1 1
7 Spacer 1
EC4H0000
TRANSMISSION, SHIFT CAM AND SHIFT FORK
Extent of removal:1Main axle, drive axle, shift cam and shift fork removal
1









1P8-9-31-4C 5/12/05 1:21 PM Page 46

5-1
CHASFRONT WHEEL AND REAR WHEEL
Extent of removal Order Part name Q’ty Remarks
FRONT WHEEL REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
1 Bolt (axle holder) 4 Only loosening.
2 Nut (front wheel axle) 1
3 Front wheel axle 1
4 Front wheel 1
5 Collar 2
6 Oil seal 2
7 Bearing 2 Refer to “REMOVAL POINTS”.
8 Brake disc 1
EC500000
CHASSISEC590000
FRONT WHEEL AND REAR WHEELEC598000
FRONT WHEEL
2
13
3
Extent of removal:1Front wheel removal2Wheel bearing removal3Brake disc removal
w
Support the machine securely so there is no dan-
ger of it falling over.
23 Nm (2.3 m•kg, 17 ft•lb)
23 Nm (2.3 m•kg, 17 ft•lb)
105 Nm (10.5 m•kg, 75 ft•lb)
12 Nm (1.2 m•kg, 8.7 ft•lb)
1C3-9-31-5A 4/22/05 1:13 PM Page 2

5-2
CHASFRONT WHEEL AND REAR WHEEL
EC598100
REAR WHEEL
Extent of removal:1Rear wheel removal2Wheel bearing removal3Brake disc removal
Extent of removal Order Part name Q’ty Remarks
REAR WHEEL REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Chain puller 2
4 Rear wheel 1 Refer to “REMOVAL POINTS”.
5 Collar 2
6 Driven sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to “REMOVAL POINTS”.
10 Brake disc 1
2
13
3
w
Support the machine securely so there is no dan-
ger of it falling over.
125 Nm (12.5 m•kg, 90 ft•lb)14 Nm (1.4 m•kg, 10 ft•lb)
16 Nm (1.6 m•kg, 11 ft•lb)
16 Nm (1.6 m•kg, 11 ft•lb)
42 Nm (4.2 m•kg, 30 ft•lb)
1C3-9-31-5A 4/22/05 1:13 PM Page 4