Fork YAMAHA YZ250F 2003 Owner's Guide

5 - 31
CHAS
Front fork cap bolt
1. Inspect:
Front fork cap bolt 1
O-ring 2
Air bleed screw 3
Wear/damage → Replace.
EC555000
ASSEMBLY AND INSTALLATION
Front fork assembly
1. Wash the all parts in a clean solvent.
2. Install:
Damper rod 1
To inner tube 2.
ACHTUNG:CAUTION:
To install the damper rod into the inner
tube, hold the inner tube aslant. If the inner
tube is held vertically, the damper rod may
fall into it, damaging the valve inside.
3. Install:
Copper washer 1
O-ring 2
Base valve 3
To inner tube 4.
4. Tighten:
Base valve 1
NOTE:
Use a damper rod holder 2 to lock the
damper rod 3.
Apply the LOCTITE® on the base valve
thread.
Damper rod holder:
YM-1423/90890-01423
T R..55 Nm (5.5 m · kg, 40 ft · lb)
FRONT FORK

5 - 32
CHAS
5. Install:
Spring guide 1
Locknut 2
To damper rod 3.
NOTE:
Install the spring guide with its cut a facing
upward.
With its thread b facing upward, fully finger
tighten the locknut onto the damper rod.
6. 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.
7. Install:
Piston metal 1
NOTE:
Install the piston metal onto the slot on inner
tube.
8. Install:
Outer tube 1
To inner tube 2.
FRONT FORK

5 - 33
CHASFRONT FORK
9. Install:
Slide metal 1
Oil seal washer 2
To outer tube slot.
NOTE:
Press the slide metal into the outer tube with
fork seal driver 3.
Fork seal driver:
YM-01442/90890-01442
10. Install:
Oil seal 1
NOTE:
Press the oil seal into the outer tube with fork
seal driver 2.
Fork seal driver:
YM-01442/90890-01442
11. Install:
Stopper ring 1
NOTE:
Fit the stopper ring correctly in the groove in
the outer tube.
12. Install:
Dust seal 1
NOTE:
Apply the lithium soap base grease on the
inner tube.

5 - 34
CHASFRONT FORK
13. Check:
Inner tube smooth movement
Tightness/binding/rough spots →
Repeat the steps 2 to 12.
14. Compress the front fork fully.
15. Fill:
Front fork oil
Until outer tube top surface with recom-
mended fork oil 1.
ACHTUNG:CAUTION:
Be sure to use recommended fork oil. If
other oils are used, they may have an
excessively adverse effect on the front
fork performance.
Never allow foreign materials to enter the
front fork.
Recommended oil:
Suspension oil “01”
16. After filling, pump the damper rod 1
slowly up and down more than 10 times
to distribute the fork oil.
17. Fill:
Front fork oil
Until outer tube top surface with recom-
mended fork oil once more.
18. After filling, pump the outer tube 1 slowly
up and down (about 200 mm (7.9 in)
stroke) to distribute the fork oil once
more.
NOTE:
Be careful not to excessive full stroke. A stroke
of 200 mm (7.9 in) or more will cause air to
enter. In this case, repeat the steps 15 to 18.

5 - 35
CHASFRONT FORK
19. Wait ten minutes until the air bubbles
have been removed from the front fork,
and the oil has dispense evenly in system
before setting recommended oil level.
NOTE:
Fill with the fork oil up to the top end of the
outer tube, or the fork oil will not spread over to
every part of the front forks, thus making it
impossible to obtain the correct level.
Be sure to fill with the fork oil up to the top of
the outer tube and bleed the front forks.
20. Measure:
Oil level (left and right) a
Out of specification → Adjust.
* For EUROPE
NOTE:
Be sure to install the spring guide 2 when
checking the oil level.
WARNING
Never fail to make the oil level adjustment
between the maximum and minimum level
and always adjust each front fork to the
same setting. Uneven adjustment can
cause poor handling and loss of stability.
Standard oil level:
140 mm (5.51 in)
* 130 mm (5.12 in)
Extent of adjustment:
80 ~ 150 mm (3.15 ~ 5.91 in)
From top of outer tube with
inner tube and damper rod 1
fully compressed without
spring.

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CHASFRONT FORK
21. Measure:
Distance a
Out of specification → Turn into the
locknut.
Distance a:
20 mm (0.79 in) or more
Between damper rod 1 top and
locknut 2 top.
22. Loosen:
Rebound damping adjuster 1
NOTE:
Loosen the rebound damping adjuster finger
tight.
Record the set position of the adjuster (the
amount of turning out the fully turned in posi-
tion).
23. Install:
Cushion rubber 1
Washer 2
Spacer 3
To front fork cap bolt 4.
NOTE:
Install the cushion rubber with its smaller
dia.end a facing the front fork cap bolt.
24. Install:
Push rod 1
Fork spring 2
NOTE:
Install the fork spring with the damper rod 3
pulled up.
After installing the fork spring, hold the
damper rod end so that it will not go down.
25. Install:
Front fork cap bolt 1
Fully tighten the front fork cap bolt onto
the damper rod by hand.

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CHASFRONT FORK
26. Tighten:
Front fork cap bolt (locknut) 1
NOTE:
While compressing the fork spring, set the
thin type spanners 2 between the spacer 3
and spring guide 4.
Hold the locknut 5 and tighten the front fork
cap bolt with specified torque.
27. Install:
Front fork cap bolt 1
To outer tube.
NOTE:
Temporarily tighten the cap bolt.
T R..29 Nm (2.9 m · kg, 21 ft · lb)
28. Install:
Protector guide 1
Installation
1. Install:
Front fork 1
NOTE:
Temporarily tighten the pinch bolts (lower
bracket).
Do not tighten the pinch bolts (upper bracket)
yet.
2. Tighten:
Front fork cap bolt 1
3. Adjust:
Front fork top end a
Front fork top end (standard) a:
5 mm (0.20 in)
T R..30 Nm (3.0 m · kg, 22 ft · lb)

5 - 38
CHASFRONT FORK
4. Tighten:
Pinch bolt (upper bracket) 1
Pinch bolt (lower bracket) 2
ACHTUNG:CAUTION:
Tighten the lower bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
5. Install:
Brake hose holder 1
Brake caliper 2
Bolt (brake caliper) 3
NOTE:
Fit the brake hose holder cut a over the pro-
jection b on the front fork and clamp the brake
hose.
6. Install:
Brake hose holder 1
Bolt (brake hose holder) 2
Protector 3
Bolt (protector) 4
NOTE:
When installing the brake hose holder, align
the top a of the brake hose neck with the
brake hose holder bottom b. Then pass the
brake hose 5 in front of the axle boss c and
fit it into the hose groove d so that the brake
hose does not contact the nut (wheel axle).
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
7. Adjust:
Rebound damping force
NOTE:
Turn in the damping adjuster 1 finger-tight
and then turn out to the originally set position.

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CHAS
EC560000
STEERING
Extent of removal:1 Lower bracket removal2 Bearing removal
Extent of removal Order Part name Q’ty Remarks
STEERING REMOVAL
WARNING
Support the machine securely so there is nodanger of it falling over.Preparation for removal Hold the machine by placing the
suitable stand under the engine.
Number plate
Handlebar
Cable guide
Front fenderRefer to “HANDLEBAR” section.
1 Steering stem nut 1
2 Front fork 2 Refer to “FRONT FORK” section.
3 Upper bracket 1
4 Steering ring nut 1 Use special tool.
Refer to “REMOVAL POINTS”.
5 Lower bracket 1
6 Ball race cover 1
7 Upper bearing 1
8 Lower bearing 1 Refer to “REMOVAL POINTS”.
9Ball race
2Refer to “REMOVAL POINTS”.
2
1
STEERING

5 - 48
CHASSTEERING
4. Install:
Steering ring nut 1
Tighten the steering ring nut using the
steering nut wrench 2.
Refer to “STEERING HEAD INSPEC-
TION AND ADJUSTMENT” section in
the CHAPTER 3.
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
5. Check the steering stem by turning it lock
to lock. If there is any binding, remove
the steering stem assembly and inspect
the steering bearings.
6. Install:
Front fork 1
Upper bracket 2
NOTE:
Temporarily tighten the pinch bolts (lower
bracket).
Do not tighten the pinch bolts (upper bracket)
yet.
7. Install:
Washer 1
Steering stem nut 2
T R..145 Nm (14.5 m · kg, 105 ft · lb)
8. After tightening the nut, check the steer-
ing for smooth movement. If not, adjust
the steering by loosening the steering
ring nut little by little.
9. Adjust:
Front fork top end a
Front fork top end (standard) a:
5 mm (0.20 in)