2006 YAMAHA YZ250F check oil

4 - 70
ENGOIL PUMP
INSPECTION
Oil pump
1. Inspect:
Oil pump drive gear 1
Oil pump drive shaft 2
Rotor housing 3
Oil pump cover 4
Cracks/wear/damage → Replace.
1
32
4
2. Measure:
Tip clearance a
(between the inner rotor 1 and outer
rotor 2)
Side clearance b
(between the outer rotor 2 and rotor
housing 3)
Housing and rotor clearance c
(between the rotor housing 3 and rotors
1 2)
Out of specification → Replace the oil
pump assembly.
Tip clearance a:
0.12 mm or less
(0.0047 in or less)
: 0.20 mm (0.008 in)
Side clearance b:
0.09 ~ 0.17 mm
(0.0035 ~ 0.0067 in)
: 0.24 mm (0.009 in)
Housing and rotor clearance c:
0.03 ~ 0.10 mm
(0.0012 ~ 0.0039 in)
: 0.17 mm (0.0067 in)
3. Check:
Unsmooth → Repeat steps #1 and #2 or
replace the defective parts.

4 - 96
ENGCRANKCASE AND CRANKSHAFT
2. Check:
Shifter operation
Transmission operation
Unsmooth operation → Repair.
3. Install:
Oil strainer 1
Bolt (oil strainer) 2
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
4. Apply:
Sealant
On the right crankcase 1.
NOTE:
Clean the contacting surface of left and right
crankcase before applying the sealant.
5. Install:
Dowel pin 1
O-ring 2
Right crankcase
To left crankcase.
NOTE:
Fit the right crankcase onto the left crank-
case. Tap lightly on the case with soft ham-
mer.
When installing the crankcase, the connect-
ing rod should be positioned at TDC (top
dead center).
YAMAHA Bond No. 1215
(ThreeBond® No. 1215):
90890-85505

4 - 97
ENGCRANKCASE AND CRANKSHAFT
6. Tighten:
Hose guide 1
Clutch cable holder 2
Bolt (crankcase) 3
NOTE:
Tighten the crankcase tightening bolts in
stage, using a crisscross pattern.
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)
7. Install:
Oil delivery pipe 2 1
O-ring 2
Bolt (oil delivery pipe 2) 3
NOTE:
Apply the lithium soap base grease on the O-
rings.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
8. Install:
Timing chain 1
Timing chain guide (intake side) 2
Bolt (timing chain guide) 3
9. Remove:
Sealant
Forced out on the cylinder mating sur-
face.
10. Apply:
Engine oil
To the crank pin, bearing and oil delivery
hole.
11. Check:
Crankshaft and transmission operation.
Unsmooth operation → Repair.
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)

4 - 100
ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
EC4H4810
Shift fork, shift cam and segment
1. Inspect:
Shift fork 1
Wear/damage/scratches → Replace.
2. Inspect:
Shift cam 1
Segment 2
Wear/damage → Replace.
3. Check:
Shift fork movement
Unsmooth operation → Replace shift
fork.
NOTE:
For a malfunctioning shift fork, replace not only
the shift fork itself but the two gears each adja-
cent to the shift fork.
EC4H5000
ASSEMBLY AND INSTALLATION
Transmission
1. Install:
5th pinion gear (24T) 1
3rd pinion gear (20T) 2
Collar 3
4th pinion gear (22T) 4
2nd pinion gear (16T) 5
To main axle 6.
NOTE:
Apply the molybdenum disulfide oil on the
inner and end surface of the idler gear and on
the inner surface of the sliding gear, then
install.

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ENGTRANSMISSION, SHIFT CAM AND SHIFT FORK
5. Install:
Shift fork 1 (L) 1
Shift fork 2 (C) 2
Shift fork 3 (R) 3
Shift cam 4
To main axle and drive axle.
NOTE:
Apply the molybdenum disulfide oil on the
shift fork grooves.
Mesh the shift fork #1 (L) with the 4th wheel
gear 5 and #3 (R) with the 5th wheel gear 7
on the drive axle.
Mesh the shift fork #2 (C) with the 3rd pinion
gear 6 on the main axle.
6. Install:
Transmission assembly 1
To left crankcase 2.
NOTE:
Apply the engine oil on the bearings and guide
bars.
7. Check:
Shifter operation
Transmission operation
Unsmooth operation → Repair.

5 - 35
CHAS
9. Check that the damper assembly is fully
stretched. Not fully stretched → Repeat the
steps 2 to 8.
10. Tighten:
Base valve 1
NOTE:
Hold the damper assembly with the cap bolt
ring wrench 2 and use the cap bolt wrench 3
to tighten the base valve with specified torque.
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501
T R..29 Nm (2.9 m · kg, 21 ft · lb)
11. After filling, pump the damper assembly 1
slowly up and down more than 10 times to
distribute the fork oil.
12. While protecting the damper assembly 1
with a rag and compressing fully, allow
excessive oil to overflow on the base valve
side.
CAUTION:
Take care not to damage the damper
assembly.
13. Allow the overflowing oil to escape at the
hole a in the damper assembly.
FRONT FORK

5 - 36
CHASFRONT FORK
14. Check:
Damper assembly smooth movement
Tightness/binding/rough spots → Repeat
the steps 2 to 13.
15. Install:
Dust seal 1
Stopper ring 2
Oil seal 3
Oil seal washer 4
Slide metal 5
To inner tube 6.
NOTE:
Apply the fork oil on the inner tube.
When installing the oil seal, use vinyl seat a
with fork oil applied to protect the oil seal lip.
Install the oil seal with its manufacture’s
marks or number facing the axle holder side.
Install the oil seal washer with its projections
b facing upward.
16. Install:
Piston metal 1
NOTE:
Install the piston metal onto the slot on inner
tube.
17. Install:
Outer tube 1
To inner tube 2.

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CHASSWINGARM
3. Install:
•Collar 1
To connecting rod 2.
NOTE:
Apply the molybdenum disulfide grease on the
collar and oil seal lips.
4. Install:
•Connecting rod 1
•Bolt (connecting rod) 2
•Washer 3
•Nut (connecting rod) 4
To relay arm 5.
NOTE:
Apply the molybdenum disulfide grease on the
bolt.
5. Install:
•Relay arm 1
•Bolt (relay arm) 2
•Washer 3
•Nut (relay arm) 4
To swingarm.
NOTE:
•Apply the molybdenum disulfide grease on
the bolt circumference and threaded portion.
•Do not tighten the nut yet.
6. Install:
•Swingarm 1
•Pivot shaft 2
NOTE:
•Apply the molybdenum disulfide grease on
the pivot shaft.
•Insert the pivot shaft from right side.
7. Check:
•Swingarm side play a
Free play exists → Replace thrust bear-
ing.
•Swingarm up and down movement b
Unsmooth movement/binding/rough
spots → Grease or replace bearings,
bushings and collars.
T R..80 Nm (8.0 m · kg, 58 ft · lb)
T R..85 Nm (8.5 m · kg, 61 ft · lb)