2001 YAMAHA YZ250F engine

4 - 74
ENGKICK SHAFT AND SHIFT SHAFT
EC4B5111
Stopper lever
1. Install:
lTorsion spring 1
lStopper lever 2
lBolt (stopper lever) 3
NOTE:
Align the stopper lever roller with the slot on
segment.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
Shift guide and shift lever assembly
1. Install:
lSpring 1
lPawl pin 2
lPawl 3
To shift lever 4.
NOTE:
Apply the engine oil on the spring, pawl pin
and pawl.
2. Install:
lShift lever assembly 1
To shift guide 2.
3. Install:
lShift lever assembly 1
lShift guide 2
NOTE:
lThe shift lever assembly is installed at the
same time as the shift guide.
lApply the engine oil on the bolt (segment)
shaft.

4 - 75
ENGKICK SHAFT AND SHIFT SHAFT
4. Install:
lBolt (shift guide) 1
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
Shift shaft
1. Install:
lRoller 1
lCollar 2
lTorsion spring 3
lShift shaft 4
NOTE:
Apply the engine oil on the roller and shift
shaft.
2. Install:
lShift pedal 1
lBolt (shift pedal) 2
NOTE:
When installing the shift pedal onto the shift
shaft, be sure that the center of the shift pedal
is about 2 mm a above the top of the footrest.
Kick shaft assembly
1. Install:
lKick gear 1
lWasher 2
lCirclip 3
lRatchet wheel 4
lSpring 5
lWasher 6
lCirclip 7
To kick shaft 8.
NOTE:
lApply the molybdenum disulfide oil on the
kick gear inner circumference.
lAlign the punch mark a on the ratchet wheel
with the punch mark b on the kick shaft.

4 - 76
ENGKICK SHAFT AND SHIFT SHAFT
2. Install:
lTorsion spring 1
To kick shaft 2.
NOTE:
Make sure the stopper a of the torsion spring
fits into the hole b on the kick shaft.
3. Install:
lSpring guide 1
NOTE:
Slide the spring guide into the kick shaft, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
lKick shaft assembly 1
lWasher 2
NOTE:
lApply the engine oil on the kick shaft.
lSlide the kick shaft assembly into the crank-
case, make sure the kick shaft stopper a fit
into their home position 3.
5. Hook:
lTorsion spring 1
NOTE:
Turn the torsion spring clockwise and hook
into the proper hole a in the crankcase.
Kick idle gear
1. Install:
lKick idle gear 1
lWasher 2
lCirclip 3
NOTE:
lApply the engine oil on the kick idle gear
inner circumference.
lInstall the kick idle gear with its depressed
side a toward you.

4 - 81
ENGENGINE REMOVAL
EC4M0000
ENGINE REMOVAL
Extent of removal Order Part name Q’ty Remarks
ENGINE REMOVAL
Preparation for removal Hold the machine by placing the
suitable stand under the frame.
WARNING
Support the machine securely so there is nodanger of it falling over.
Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Clutch cable Disconnect at engine side.
Decompression cable and guide Disconnect at engine side.
Radiator Refer to “RADIATOR” section.
Shift pedal Refer to “KICK SHAFT AND SHIFT
SHAFT” section.
Cylinder head breather hose and
oil tank breather hoseRefer to “CAMSHAFTS” section.
Drain the engine oil Refer to “ENGINE OIL REPLACEMENT”
section in the CHAPTER 3.

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ENGENGINE REMOVAL
Extent of removal:1 Engine removal
Extent of removal Order Part name Q’ty Remarks
Spark plug cap
Disconnect the CDI magneto lead.
Right engine guard
1 Neutral switch 1
2 Bolt (oil hose) 2
3 Drive chain sprocket cover 1
4 Nut (drive sprocket) 1
Refer to “REMOVAL POINTS”. 5 Lock washer 1
6 Drive sprocket 1
7 Clip 1
8 Bolt (brake pedal) 1
9 Brake pedal 1
10 Upper engine bracket 2
11 Lower engine bracket 2
12 Engine mounting bolt 3
13 Pivot shaft 1
Refer to “REMOVAL POINTS”.
14Engine
1
1

4 - 83
ENGENGINE REMOVAL
EC4M3000
REMOVAL POINTS
EC4F3100
Drive sprocket
1. Remove:
lNut (drive sprocket) 1
lLock washer 2
NOTE:
lStraighten the lock washer tab.
lLoosen the nut while applying the rear brake.
2. Remove:
lDrive sprocket 1
lDrive chain 2
NOTE:
Remove the drive sprocket together with the
drive chain.
EC4M3301
Engine removal
1. Remove:
lPivot shaft 1
NOTE:
If the pivot shaft is pulled all the way out, the
swingarm will come loose. If possible, insert a
shaft of similar diameter into the other side of
the swingarm to support it.
2. Remove:
lEngine 1
From right side.
NOTE:
Make sure that the couplers, hoses and cables
are disconnected.

4 - 84
ENGENGINE REMOVAL
EC4M5000
ASSEMBLY AND INSTALLATION
Engine installation
1. Install:
lEngine 1
Install the engine from right side.
lPivot shaft 2
lEngine mounting bolt (lower) 3
lLower engine bracket 4
lBolt (engine bracket) 5
lEngine mounting bolt (front) 6
lUpper engine bracket 7
lEngine mounting bolt (upper) 8
T R..85 Nm (8.5 m · kg, 61 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..69 Nm (6.9 m · kg, 50 ft · lb)
T R..55 Nm (5.5 m · kg, 40 ft · lb)
EC4M5211
Brake pedal
1. Install:
lSpring 1
lBrake pedal 2
lO-ring 3
lBolt (brake pedal) 4
lClip 5
NOTE:
lApply the lithium soap base grease on the
bolt, O-rings and brake pedal bracket.
lInstall the clip with its stopper portion a fac-
ing inward.
T R..26 Nm (2.6 m · kg, 19 ft · lb)
Drive sprocket
1. Install:
lDrive sprocket 1
lDrive chain 2
NOTE:
Install the drive sprocket together with the
drive chain.

4 - 85
ENGENGINE REMOVAL
2. Install:
lLock washer 1
lNut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
T R..75 Nm (7.5 m · kg, 54 ft · lb)
3. Bend the lock washer tab to lock the nut.
4. Install:
lDrive chain sprocket guide 1
lDrive chain sprocket cover 2
lScrew (drive chain sprocket cover) 3
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
Oil hose and neutral switch
1. Install:
lO-ring 1
lDowel pin 2
lOil hose 3
lBolt (oil hose) 4
NOTE:
Apply the lithium soap base grease on the O-
ring.
2. Install:
lSpring 1
lPin 2
lO-ring 3
lNeutral switch 4
lBolt (neutral switch) 5
NOTE:
Apply the lithium soap base grease on the O-
ring.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)