2006 YAMAHA YZ250LC engine

4-32
CYLINDER HEAD, CYLINDER AND PISTONENG
9. Install:
9Spark plug 1
9Spark plug cap 2
8. Install:
9Engine bracket 1
9Bolt (engine bracket) 2
9Engine mounting bolt (upper) 3
20 Nm (2.0 m•kg, 14 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
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4-33
CLUTCH AND PRIMARY DRIVEN GEARENG
Extent of removal Order Part name Q’ty Remarks
CLUTCH PLATE AND
FRICTION PLATE REMOVAL
Preparation for Drain the transmission oil.
Refer to “TRANSMISSION OIL REPLACE-
removalMENT” section in the CHAPTER 3.
Bolt (brake pedal) Shift the brake pedal downward.
Rotor and stator Refer to
“CDI MAGNETO”section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Screw (clutch spring) 6
3 Clutch spring 6
4 Pressure plate 1
5 Friction plate 8
6 Clutch plate 7
Extent of removal:1Clutch plate and friction plate removal
EC490000
CLUTCH AND PRIMARY DRIVEN GEAREC498000
CLUTCH PLATE AND FRICTION PLATE
1
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
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Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for
Hold the machine by placing the
removalsuitable stand under the engine.
Drain the transmission oil. Refer to “TRANSMISSION OIL
REPLACEMENT” section in the
CHAPTER 3.
Seat and fuel tankRefer to “SEAT, FUEL TANK AND
SIDE COVERS” section.
CarburetorRefer to “CARBURETOR AND REED
VALVE” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
Exhaust pipe stay (rear) SILENCER” section.
Clutch cable Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Spark plug
Disconnect the CDI magneto lead.
4-60
ENGINE REMOVALENG
EC4M0000
ENGINE REMOVAL
w
Support the machine securely so there is no dan-
ger of it falling over.



26 Nm (2.6 m•kg, 19 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
75 Nm (7.5 m•kg, 54 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
åExcept for USA and CDN
4 Nm (0.4 m•kg, 2.9 ft•lb)
1P8-9-31-4C 5/12/05 1:20 PM Page 22

Extent of removal Order Part name Q’ty Remarks
1 Neutral switch 1 Disconnect the neutral switch lead.
2 Chain cover 1
3 Nut (drive sprocket) 1
4 Lock washer 1 Refer to “REMOVAL POINTS”.
5 Drive sprocket 1
6 Clip 1
7 Bolt (brake pedal) 1
8 Brake pedal 1
9 Engine bracket 2
10 Engine mounting bolt 3
11 Pivot shaft 1 Remove completely.
12 Engine 1 Refer to “REMOVAL POINTS”.
4-61
ENGINE REMOVALENG
Extent of removal:1Engine removal
1
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26 Nm (2.6 m•kg, 19 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
75 Nm (7.5 m•kg, 54 ft•lb)
5 Nm (0.5 m•kg, 3.6 ft•lb)
34 Nm (3.4 m•kg, 24 ft•lb)
64 Nm (6.4 m•kg, 46 ft•lb)
85 Nm (8.5 m•kg, 61 ft•lb)
åExcept for USA and CDN
4 Nm (0.4 m•kg, 2.9 ft•lb)
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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”.
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
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12
3
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




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