YAMAHA WR 250F 2008 Owners Manual

5-65
TRANSMISSION, SHIFT CAM AND SHIFT FORK
4. Install:•Collar "1"
• Apply the lithium soap base grease on the oil seal lip.
• When installing the collar into the crankcase, pay careful attention to
the crankcase oil seal lip.
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.
• 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 ax-
le.
6. Install:
• Transmission assembly "1"To left crankcase "2".
Apply the engine oil on the bearings
and guide bars.
7. Check:• Shifter operation
• Transmission operation
Unsmooth operation →Repair.

6-1
FRONT WHEEL AND REAR WHEEL
CHASSIS
FRONT WHEEL AND REAR WHEEL
REMOVING THE FRONT WHEELOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
1 Bolt (axle holder) 4 Only loosening.
2 Nut (front wheel axle) 1
3 Front wheel axle 1
4 Front wheel 1
5 Speed sensor 1
6 Collar 1
7 Oil seal 1
8 Bearing 2 Refer to removal section.
9 Brake disc 1
21 Nm (2.1 m kg, 15 ft lb)
21 Nm (2.1 m kg, 15 ft lb)
12 Nm (1.2 m kg, 8.7 ft lb)
90 Nm (9.0 m kg, 65 ft lb)

6-2
FRONT WHEEL AND REAR WHEEL
REMOVING THE REAR WHEELOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
1 Nut (rear wheel axle) 1
2 Rear wheel axle 1
3 Drive chain puller 2
4 Rear wheel 1 Refer to removal section.
5 Collar 2
6 Rear wheel sprocket 1
7 Oil seal 2
8 Circlip 1
9 Bearing 2 Refer to removal section.
10 Brake disc 1
125 Nm (12.5 m kg, 90 ft lb)
14 Nm (1.4 m kg, 10 ft lb)
19 Nm (1.9 m kg, 13 ft lb)
19 Nm (1.9 m kg, 13 ft lb)
50 Nm (5.0 m kg, 36 ft lb)
6

6-3
FRONT WHEEL AND REAR WHEEL
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
REMOVING THE REAR WHEEL
1. Remove:• Wheel "1"
Push the wheel forward and remove
the drive chain "2".
REMOVING THE WHEEL BEARING
1. Remove:• Bearing "1"
Remove the bearing using a general
bearing puller "2".
CHECKING THE WHEEL
1. Measure:• Wheel runout
Out of limit → Repair/replace.
2. Inspect: • BearingRotate inner race with a finger.
Rough spot/seizure → Replace.
Replace the bearings, oil seal and
wheel collar as a set.
CHECKING THE WHEEL AXLE
1. Measure:
• Wheel axle bendsOut of specification → Replace.
Use the dial gauge "1".
The bending value is shown by one
half of the dial gauge reading.
Do not attempt to straighten a bent
axle.
CHECKING THE BRAKE DISC
1. Measure: • Brake disc deflection (only rear
brake disc)
Use the dial gauge "1".
Out of specification → Inspect
wheel runout.
If wheel runout is in good condi-
tion, replace the brake disc.
2. Measure: • Brake disc thickness "a"
Out of limit → Replace. INSTALLING THE FRONT WHEEL
1. Install:
• Bearing (left) "1"
• Spacer "2"
• Bearing (right) "3"
• Oil seal "4"
• Apply the lithium soap base grease on the bearing and oil seal lip when
installing.
• Use a socket that matches the out-
side diameter of the race of the
bearing.
• Left side of bearing shall be in- stalled first.
• Install the oil seal with its manufac-
ture's marks or numbers facing out-
ward.
Do not strike the inner race of the
bearing. Contact should be made
only with the outer race.
Wheel runout limit: Radial "1": 2.0 mm
(0.08 in)
Lateral "2": 2.0 mm
(0.08 in)
Wheel axle bending limit:
0.5 mm (0.020 in)
Brake disc deflection lim-
it: Rear:
: 0.15 mm
(0.006 in)
Brake disc thickness: Front:3.0 mm (0.12 in)
: 2.5 mm (0.10
in)
Rear:
4.0 mm (0.16 in)
: 3.5 mm (0.14
in)

6-4
FRONT WHEEL AND REAR WHEEL
2. Install:• Brake disc "1"
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:•Collar "1"
Apply the lithium soap base grease
on the oil seal lip.
4. Install:• Speed sensor "1"
• Apply the lithium soap base grease on the oil seal lip of the speed sen-
sor.
• Make sure the two projections "a" in the wheel hub are meshed with the
two slots "b" in the speed sensor.
5. Install:• Wheel
• Install the brake disc "1" between
the brake pads "2" correctly.
• Make sure that the projections "a" in the speed sensor fits over the stop-
per "b" on the front fork inner tube.
6. Install:• Wheel axle "1"
Apply the lithium soap base grease
on the wheel axle.
7. Install:• Nut (wheel axle) "1"
8. Tighten: • Bolt (axle holder) "1"
Before tightening the bolt, fit the
wheel axle to the axle holder by strok-
ing the front fork several times with
the front brake applied.
INSTALLING THE REAR WHEEL
1. Install:• Bearing (right) "1"
• Circlip "2"
• Spacer "3"
• Bearing (left) "4"
• Oil seal "5"
• Apply the lithium soap base grease on the bearing and oil seal lip when
installing.
• Install the bearing with seal facing outward.
• Use a socket that matches the out-
side diameter of the race of the
bearing.
• Right side of bearing shall be in- stalled first.
• Install the oil seal with its manufac-
ture's marks or numbers facing out-
ward.
Do not strike the inner race of the
bearing. Contact should be made
only with the outer race.
Bolt (brake disc): 12 Nm (1.2 m•kg, 8.7
ft•lb)
Nut (wheel axle):
90 Nm (9.0 m•kg, 65
ft•lb)
Bolt (axle holder): 21 Nm (2.1 m•kg, 15
ft•lb)

6-5
FRONT WHEEL AND REAR WHEEL
2. Install:• Brake disc "1"
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:• Rear wheel sprocket "1"
• Bolt (rear wheel sprocket) "2"
• Washer (rear wheel sprocket) "3"
• Nut (rear wheel sprocket) "4"
Tighten the nuts in stage, using a
crisscross pattern.
4. Install:•Collar "1"
Apply the lithium soap base grease
on the oil seal lip.
5. Install:• Wheel
Install the brake disc "1" between the
brake pads "2" correctly.
6. Install:• Drive chain "1"
Push the wheel "2" forward and install
the drive chain.
7. Install:
• Left drive chain puller "1"
• Wheel axle "2"
• Install the left drive chain puller, and insert the wheel axle from left side.
• Apply the lithium soap base grease
on the wheel axle.
8. Install:• Right drive chain puller "1"
• Washer "2"
• Nut (wheel axle) "3"
Temporarily tighten the nut (wheel
axle) at this point.
9. Adjust:• Drive chain slack "a"
Refer to "ADJUSTING THE
DRIVE CHAIN SLACK" section in
the CHAPTER 3. 10. Tighten:
• Nut (wheel axle) "1"
• Locknut "2"
Bolt (brake disc):
14 Nm (1.4 m•kg, 10
ft•lb)
Nut (rear wheel sprock-
et): 50 Nm (5.0 m•kg, 36
ft•lb)
Drive chain slack:48–58 mm (1.9–2.3 in)
Nut (wheel axle):
125 Nm (12.5 m•kg, 90
ft•lb)
Locknut: 19 Nm (1.9 m•kg, 13
ft•lb)

6-6
FRONT BRAKE AND REAR BRAKE
FRONT BRAKE AND REAR BRAKE
REMOVING THE FRONT BRAKEOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
Drain the brake fluid. Refer to removal section.
1 Brake hose holder (protector) 2
2 Brake hose holder (brake caliper) 1
3 Union bolt 2
4 Brake hose 1
5 Pad pin plug 1 Remove when loosening the pad pin.
6Pad pin 1Loosen when disassembling the brake cali-
per.
7 Brake caliper 1
8Brake lever 1
9 Brake master cylinder bracket 1
10 Brake master cylinder 1

6-7
FRONT BRAKE AND REAR BRAKE
REMOVING THE REAR BRAKEOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
Rear wheel Refer to "FRONT WHEEL AND REAR
WHEEL" section.
Drain the brake fluid. Refer to removal section.
1 Brake pedal 1
2 Brake master cylinder 1
3 Brake hose holder 2
4 Union bolt 2
5 Brake hose 1
6 Pad pin plug 1 Remove when loosening the pad pin.
7Pad pin 1Loosen when disassembling the brake cali-
per.
8 Brake caliper 1

6-8
FRONT BRAKE AND REAR BRAKE
DISASSEMBLING THE BRAKE CALIPEROrder Part name Q'ty Remarks A. Front
B. Rear
AB
1Pad pin 11
2 Brake pad 2 2
3 Pad support 1 1
4 Brake caliper piston 2 1 Refer to removal section.
5 Brake caliper piston dust s eal2 1 Refer to removal section.
6 Brake caliper piston seal 2 1 Refer to removal section.

6-9
FRONT BRAKE AND REAR BRAKE
DISASSEMBLING THE BRAKE MASTER CYLINDEROrder Part name Q'ty Remarks A. Front
B. Rear
1 Brake master cylinder cap 1
2 Diaphragm 1
3 Reservoir float 1
4 Brake master cylinder boot 1
5 Circlip 1 Use a long nose circlip pliers.
6 Washer 1
7 Push rod 1
8 Brake master cylinder kit 1