2001 YAMAHA WR 426F engine oil

4 - 74
ENGOIL PUMP
INSPECTION
Oil pump
1. Inspect:
lOil pump drive gear
lOil pump driven gear
lRotor housing
lOil pump cover
Cracks/wear/damage ® Replace.
2. Measure:
lTip clearance a
Between the inner rotor 1 and the
outer rotor 2.
lTip clearance b
Between the outer rotor 2 and the rotor
housing 3.
Out of specification ® Replace the oil
pump.
Tip clearance a:
0.12 mm or less
(0.0047 in or less)
: 0.20 mm (0.006 in)
Tip clearance b:
0.09 ~ 0.17 mm (0.0035 ~ 0.0067 in)
: 0.24 mm (0.009 in)
Side clearance c:
0.03 ~ 0.10 mm (0.0012 ~ 0.0039 in)
: 0.17 mm (0.007 in)
3. Check:
lUnsmooth ® Repeat steps #1 and #2
or replace the defective parts.
ASSEMBLY AND INSTALLATION
Oil pump
1. Install:
lOil pump drive shaft 1
lWasher 2
lPin 3
lInner rotor 1 4
NOTE:
lApply the engine oil on the oil pump drive
shaft and inner rotor 1.
lFit the pin into the groove in the inner rotor 1.

4 - 75
ENGOIL PUMP
2. Install:
lOuter rotor 1 1
NOTE:
Apply the engine oil on the outer rotor 1.
3. Install:
lOil pump cover 1
lScrew (oil pump cover) 2
lPin 3
lInner rotor 2 4
lCirclip 5
NOTE:
lApply the engine oil on the oil pump drive
shaft end and inner rotor 2.
lFit the pin into the groove in the inner rotor 2.
4. Install:
lOuter rotor 2 1
lDowel pin 2
lOil pump assembly 3
lBolt (oil pump assembly)
[L = 30 mm (1.18 in)] 4
lBolt (oil pump assembly)
[L = 25 mm (0.98 in)] 5
NOTE:
Apply the engine oil on the outer rotor 2.
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
5. Install:
lOil pump drive gear 1
lPlate washer 2
lCirclip 3
NOTE:
Apply the engine oil on the oil pump drive gear
inner circumference.
New

4 - 80
ENGKICK AXLE 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 springs, pawl pins
and pawls.
2. Install:
lShift lever assembly 1
To shift guide 2.2
1
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 - 81
ENGKICK AXLE AND SHIFT SHAFT
4. Install:
lBolt (shift guide) 1
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
EC4C5301
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.
Kick axle assembly
1. Install:
lKick gear 1
lPlain washer 2
lCirclip 3
lRatchet wheel 4
lSpring 5
lPlain washer 6
lCirclip 7
To kick axle 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 axle.
New
New
2. Install:
lTorsion spring 1
To kick axle 2.
NOTE:
Make sure the stopper a of the torsion spring
fits into the hole b on the kick axle.

4 - 82
ENGKICK AXLE AND SHIFT SHAFT
3. Install:
lSpring guide 1
NOTE:
Slide the spring guide into the kick axle, make
sure the groove a in the spring guide fits on
the stopper of the torsion spring.
4. Install:
lKick axle assembly 1
lPlain washer 2
NOTE:
lApply the engine oil on the kick axle.
lSlide the kick axle assembly into the crank-
case, make sure the kick axle 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
lPlain washer 2
lCirclip 3
NOTE:
lInstall the kick idle gear with its depressed
side a toward you.
lApply the engine oil on the kick idle gear
inner circumference.
New

ENG
4 - 87
ENGINE 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 “CDI MAGNETO” 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.
Spark plug cap
Disconnect the CDI magneto lead.

ENG
4 - 88
ENGINE REMOVAL
Extent of removal:1 Engine removal
Extent of removal Order Part name Q’ty Remarks
1 Engine skidplate 1
2 Neutral switch 1
3 Oil hose 2
4 Chain cover 1
Refer to “REMOVAL POINTS”. 5 Nut (drive sprocket) 1
6 Lock washer 1
7 Drive sprocket 1
8 Clip 1
9 Bolt (brake pedal) 1
10 Brake pedal 1
11 Engine upper bracket (right) 1
12 Engine upper bracket (left) 1
13 Engine lower bracket 2
14 Engine mounting bolt 3
15 Pivot shaft 1
Refer to “REMOVAL POINTS”.
16 Engine 1
1

4 - 91
ENGENGINE REMOVAL
2. Install:
lLock washer 1
lNut (drive sprocket) 2
NOTE:
Tighten the nut while applying the rear brake.
New
T R..75 Nm (7.5 m · kg, 54 ft · lb)
3. Bend the lock washer tab to lock the nut.
4. Install:
lChain guide
lChain cover 1
lScrew (chain cover) 2
T R..8 Nm (0.8 m · kg, 5.8 ft · lb)
5. Install:
lOil hose 1
lBolt (oil hose) 2
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
6. 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.
New
T R..4 Nm (0.4 m · kg, 2.9 ft · lb)