2008 YAMAHA YZ250F Owners Manual

5-29
STEERING
9 Bearing race2 Refer to removal section.
Order
Part name Q'tyRemarks

5-30
STEERING
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE STEERING RING
NUT
1. Remove:• Steering ring nut "1"Use the steering nut wrench "2".
Support the steering stem so that
it may not fall down.
REMOVING THE LOWER
BEARING
1. Remove:
• Lower bearing "1"Use the floor chisel "2".
Take care not to damage the steer-
ing shaft thread.
REMOVING THE BEARING RACE
1. Remove:
• Bearing race "1"Remove the bearing race using
long rod "2" and the hammer.
CHECKING THE STEERING STEM
1. Inspect: • Steering stem "1"
Bend/damage
→Replace. CHECKING THE BEARING AND
BEARING RACE
1. Wash the bearings and bearing
races with a solvent.
2. Inspect: • Bearing "1"
• Bearing racePitting/damage
→Replace bear-
ings and bearing races as a set.
Install the bearing in the bearing
races. Spin the bearings by hand.
If the bearings hang up or are not
smooth in their operation in the
bearing races, replace bearings
and bearing races as a set.
INSTALLING THE LOWER
BRACKET
1. Install: • Lower bearing "1"
Apply the lithium soap base grease
on the dust seal lip and bearing inner
circumference.
2. Install:
• Bearing race
• Upper bearing "1"
• Bearing race cover "2"
Apply the lithium soap base grease
on the bearing and bearing race cov-
er lip.
3. Install:• Lower bracket "1"
Apply the lithium soap base grease
on the bearing, the portion "a" and
thread of the steering stem.
4. Install:• Steering ring nut "1"
Tighten the steering ring nut using
the steering nut wrench "2".
Refer to "CHECKING AND AD-
JUSTING THE STEERING
HEAD" section in the CHAPTER
3.
5. Check the steering stem by turn- ing it lock to lock. If there is any
binding, remove the steering stem
assembly and inspect the steer-
ing bearings.
Steering nut wrench:
YU-33975/90890-01403
Steering ring nut:7 Nm (0.7 m•kg, 5.1 ft•
lb)

5-31
STEERING
6. Install:• Washer "1"
7. Install: • Front fork "1"
• Upper bracket "2"
• Temporarily tighten the pinch bolts
(lower bracket).
• Do not tighten the pinch bolts (up-
per bracket) yet.
8. Install:• Washer "1"
• Steering stem nut "2"
9. After tightening the nut, check the steering for smooth movement. If
not, adjust the steering by loosen-
ing the steering ring nut little by lit-
tle.
10. Adjust:
• Front fork top end "a" 11. Tighten:
• Pinch bolt (upper bracket) "1"
• Pinch bolt (lower bracket) "2"
Tighten the lower bracket to speci-
fied torque. If torqued too much, it
may cause the front fork to mal-
function.
Steering stem nut: 145 Nm (14.5 m•kg, 105
ft•lb)
Front fork top end (stan-
dard) "a": 5 mm (0.20 in)
Pinch bolt (upper brack-
et):21 Nm (2.1 m•kg, 15
ft•lb)
Pinch bolt (lower brack-
et): 21 Nm (2.1 m•kg, 15
ft•lb)

5-32
SWINGARM
SWINGARM
REMOVING THE SWINGARMOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
Brake hose holder Refer to "FRONT BRAKE AND REAR
BRAKE" section.
Rear brake caliper Refer to "FRONT BRAKE AND REAR
BRAKE" section.
Bolt (brake pedal) Shift the brake pedal backward.
Drive chain
1 Drive chain support 1
2 Lower chain tensioner 1
3 Bolt (rear shock absorber-relay arm) 1 Hold the swingarm.
4 Bolt (connecting rod) 1
5Pivot shaft 1
6 Swingarm 1

5-33
SWINGARM
DISASSEMBLING THE SWINGARMOrder Part name Q'ty Remarks1 Cap 2 Refer to removal section.
2 Relay arm 1
3 Connecting rod 1
4Collar 2
5 Oil seal 2
6 Thrust bearing 2
7 Bushing 2
8 Oil seal 8
9 Bearing 10 Refer to removal section.

5-34
SWINGARM
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE CAP
1. Remove:• Left cap "1"
Remove with a slotted-head screw-
driver inserted under the mark "a" on
the left cap.
REMOVING THE BEARING
1. Remove:• Bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE SWINGARM
1. Inspect:
• Bearing "1"
• Bushing "2"Free play exists/unsmooth revolu-
tion/rust
→Replace bearing and
bushing as a set.
2. Inspect:
•Oil seal "3"Damage
→Replace.
CHECKING THE RELAY ARM
1. Inspect: • Bearing "1"
•Collar "2"Free play exists/unsmooth revolu-
tion/rust
→ Replace bearing and
collar as a set. 2. Inspect:
• Oil seal "3"Damage
→Replace.
CHECKING THE CONNECTING
ROD
1. Inspect: • Bearing "1"
•Collar "2"
Free play exists/unsmooth revolu-
tion/rust
→Replace bearing and
collar as a set.
2. Inspect: • Oil seal "3"
Damage
→Replace.
INSTALLING THE BEARING AND
OIL SEAL
1. Install: • Bearing "1"
• Oil seal "2"To swingarm.
• Apply the molybdenum disulfide grease on the bearing when install-
ing.
• Install the bearing by pressing it on the side having the manufacture's
marks or numbers.
• First install the outer and then the inner bearings to a specified depth
from inside.
2. Install:• Bearing "1"
• Washer "2"
•Oil seal "3"To relay arm.
• Apply the molybdenum disulfide grease on the bearing when install-
ing.
• Install the bearing by pressing it on the side having the manufacture's
marks or numbers.
• Apply the molybdenum disulfide grease on the washer.
3. Install:• Bearing "1"
•Oil seal "2"To connecting rod.
• Apply the molybdenum disulfide grease on the bearing when install-
ing.
• Install the bearing by pressing it on the side having the manufacture's
marks or numbers.
Installed depth of bear-
ings: Outer "a": Zero mm
(Zero in)
Inner "b": 6.5 mm (0.26
in)
Installed depth of bear-
ings "a":
Zero mm (Zero in)
Installed depth of bear-
ings "a": Zero mm (Zero in)

5-35
SWINGARM
INSTALLING THE SWINGARM
1. Install:• Bushing "1"
• Thrust bearing "2"
•Oil seal "3"
•Collar "4"To swingarm "5".
Apply the molybdenum disulfide
grease on the bushings, thrust bear-
ings, oil seal lips and contact surfaces
of the collar and thrust bearing.
2. Install:
•Collar "1"
• Washer "2"To relay arm "3".
Apply the molybdenum disulfide
grease on the collars and oil seal lips.
3. Install:•Collar "1"To connecting rod "2".
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".
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.
• 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"
• 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
bearing. • Swingarm up and down move-
ment "b"
Unsmooth movement/binding/
rough spots
→Grease or replace
bearings, bushings and collars.
8. Install: • Bolt (connecting rod) "1"
• Washer "2"
• Nut (connecting rod) "3"
• Apply the molybdenum disulfide grease on the bolt.
• Do not tighten the nut yet.
9. Install: • Bolt (rear shock absorber-relay
arm) "1"
• Nut (rear shock absorber-relay arm) "2"
Apply the molybdenum disulfide
grease on the bolt.
10. Tighten:• Nut (connecting rod) "1"
Nut (connecting rod):
80 Nm (8.0 m•kg, 58
ft•lb)
Pivot shaft: 85 Nm (8.5 m•kg, 61
ft•lb)
Nut (rear shock absorb-
er-relay arm):53 Nm (5.3 m•kg, 38
ft•lb)
Nut (connecting rod): 80 Nm (8.0 m•kg, 58
ft•lb)

5-36
SWINGARM
11. Tighten:• Nut (relay arm) "1"
12. Install: • Cap "1"
Install the right cap with its mark "a"
facing forward.
13. Install:• Bolt (lower chain tensioner) "1"
• Washer "2"
•Collar "3"
• Lower chain tensioner "4"
• Nut (lower chain tensioner) "5"
14. Install: • Drive chain support "1"
• Drive chain support cover "2"
• Bolt {drive chain support [L = 50 mm (1.97 in)]} "3" • Nut (drive chain support) "4"
• Bolt {drive chain support cover [L
= 10 mm (0.39 in)]} "5"
Nut (relay arm): 70 Nm (7.0 m•kg, 50
ft•lb)
Nut (lower chain tension-
er): 16 Nm (1.6 m•kg, 11
ft•lb)
Nut (drive chain sup-
port):7 Nm (0.7 m•kg, 5.1
ft•lb)
Bolt (drive chain support
cover): 7 Nm (0.7 m•kg, 5.1
ft•lb)