2008 YAMAHA YZ250F Owners Manual

5-13
FRONT BRAKE AND REAR BRAKE
2. Install:• Brake lever "1"
• Bolt (brake lever) "2"
• Nut (brake lever) "3"
Apply the silicone grease on the
brake lever sliding surface, bolt and
tip of the push rod.
INSTALLING THE REAR BRAKE
MASTER CYLINDER
1. Install:• Copper washer "1"
•Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake master cylinder.
2. Install:• Brake master cylinder "1" • Bolt (brake master cylinder) "2"
3. Install: • Spring "1"
• Brake pedal "2"
• O-ring "3"
• Bolt (brake pedal) "4"
•Clip "5"
Apply the lithium soap base grease
on the bolt, O-ring and brake pedal
bracket.
4. Install:•Pin "1"
•Washer "2"
• Cotter pin "3"
After installing, check the brake pedal
height. Refer to "ADJUSTING THE
REAR BRAKE" section in the CHAP-
TER 3.
INSTALLING THE FRONT BRAKE
HOSE
1. Install:• Copper washer "1"
• Brake hose "2" • Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake caliper.
2. Install:
• Brake hose holder "1"
• Nut (brake hose holder) "2"
Align the top "a" of the brake hose
holder with the paint "b" of the brake
hose.
3. Pass the brake hose through the
cable guide "1".
Bolt (brake lever):
6 Nm (0.6 m•kg, 4.3
ft•lb)
Nut (brake lever): 6 Nm (0.6 m•kg, 4.3
ft•lb)
Union bolt: 30 Nm (3.0 m•kg, 22
ft•lb)
Bolt (brake master cylin-
der):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (brake pedal): 26 Nm (2.6 m•kg, 19
ft•lb)Union bolt:
30 Nm (3.0 m•kg, 22
ft•lb)
Nut (brake hose holder): 7 Nm (0.7 m•kg, 5.1 ft
•lb)

5-14
FRONT BRAKE AND REAR BRAKE
4. Install:• Copper washer "1"
•Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake master cylinder.
INSTALLING THE REAR BRAKE
HOSE
1. Install:• Copper washer "1"
•Brake hose "2"
• Union bolt "3"
Always use new copper washers.
Install the brake hose so that its
pipe portion "a" directs as shown
and lightly touches the projection
"b" on the brake caliper.
2. Install:• Brake hose holder "1"
• Screw (brake hose holder) "2"
After installing the brake hose
holders, make sure the brake hose
does not contact the spring (rear
shock absorber). If it does, correct
its twist.
FILLING THE BRAKE FLUID
1. Fill:•Brake fluid
Until the fluid level reaches
"LOWER" level line "a".
• Use only the designated quality brake fluid:
otherwise, the rubber seals may
deteriorate, causing leakage and
poor brake performance.
• Refill with the same type of brake
fluid;
mixing fluids may result in a
harmful chemical reaction and
lead to poor performance.
• Be careful that water does not enter the master cylinder when
refilling. Water will significantly lower the boiling point of the flu-
id and may result in vapor lock.
Brake fluid may erode painted sur-
faces or plastic parts. Always
clean up spilled fluid immediately.
A. Front
B. Rear
2. Air bleed: • Brake system
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion in the CHAPTER 3.
3. Inspect: • Brake fluid levelFluid at lower level
→Fill up.
Refer to "CHECKING THE
BRAKE FLUID LEVEL" section in
the CHAPTER 3.
4. Install: • Reservoir float (front brake)
• Diaphragm
• Brake master cylinder cap "1"
• Screw (brake master cylinder cap) "2"
After installation, while pulling the
brake lever in or pushing down on
the brake pedal, check whether
there is any brake fluid leaking
where the union bolts are installed
respectively at the brake master
cylinder and brake caliper.
Union bolt:
30 Nm (3.0 m•kg, 22
ft•lb)
Union bolt: 30 Nm (3.0 m•kg, 22
ft•lb)
Screw (brake hose hold-
er):2 Nm (0.2 m•kg, 1.4
ft•lb)
Recommended brake flu-
id: DOT #4
Screw (bolt) {brake mas-
ter cylinder cap}:2 Nm (0.2 m•kg, 1.4
ft•lb)

5-15
FRONT BRAKE AND REAR BRAKE
A. Front
B. Rear
5. Install: (rear brake only)
• Protector "1"
• Bolt (protector) "2"
Bolt (protector):7 Nm (0.7 m•kg, 5.1
ft•lb)

5-16
FRONT FORK
FRONT FORK
REMOVING THE FRONT FORKOrder Part name Q'ty Remarks Hold the machine by placing the suitable stand
under the engine. Refer to "HANDLING NOTE".
Front wheel Refer to "FRONT WHEEL AND REAR
WHEEL" section.
Front brake caliper Refer to "FRONT BRAKE AND REAR
BRAKE" section.
Number plate Refer to "SEAT, FUEL TANK AND SIDE
COVERS" section in the CHAPTER 4.
1Protector 1
2 Pinch bolt (upper bracket) 2 Only loosening.
3 Damper assembly 1Loosen when disassembling the front fork.
Refer to removal section.
4 Pinch bolt (lower bracket) 2 Only loosening.
5 Front fork 1
21 Nm (2.1 m kg, 15 ft lb)
21 Nm (2.1 m kg, 15 ft lb)
5 Nm (0.5 m kg, 3.6 ft lb)
5 Nm (0.5 m kg, 3.6 ft lb)
7 Nm (0.7 m kg, 5.1 ft lb)

5-17
FRONT FORK
DISASSEMBLING THE FRONT FORKOrder Part name Q'ty Remarks1 Adjuster 1 Drain the fork oil. Refer to removal section.
2 Fork spring 1 Drain the fork oil.
3 Dust seal 1 Refer to removal section.
4 Stopper ring 1 Refer to removal section.
5 Inner tube 1 Refer to removal section.
6 Outer tube 1
7 Piston metal 1
8 Slide metal 1
9 Oil seal washer 1
10 Oil seal 1
11 Base valve 1 Drain the fork oil. Refer to removal section.
12 Damper assembly 1 Drain the fork oil. Refer to removal section.
30 Nm (3.0 m kg, 22 ft lb)
29 Nm (2.9 m kg, 21 ft lb)
29 Nm (2.9 m kg, 21 ft lb)
1 Nm (0.1 m kg, 0.7 ft lb)
55 Nm (5.5 m kg, 40 ft lb)

5-18
FRONT FORK
HANDLING NOTE
Support the machine securely so
there is no danger of it falling over.
The front fork requires careful atten-
tion. So it is recommended that the
front fork be maintained at the deal-
ers.
To prevent an accidental explosion
of air, the following instructions
should be observed:
• The front fork with a built-in pis-ton rod has a very sophisticated
internal construction and is par-
ticularly sensitive to foreign ma-
terial. Use enough care not to
allow any foreign material to
come in when the oil is replaced
or when the front fork is disas-
sembled and reassembled.
• Before removing the base valves or front forks, be sure to extract
the air from the air chamber com-
pletely.
REMOVING THE DAMPER
ASSEMBLY
1. Loosen:
• Damper assembly "1"
Before removing the front fork from
the machine, loosen the damper as-
sembly with the cap bolt ring wrench
"2".
REMOVING THE ADJUSTER
1. Drain the outer tube of its front fork oil at its top.
2. Loosen: •Adjuster "1" 3. Remove:
• Adjuster "1"
• While compressing the inner tube "2", set the cap bolt ring wrench "4"
between the inner tube and locknut
"3".
• Hold the locknut and remove the adjuster.
Do not remove the locknut as the
damper rod may go into the damp-
er assembly and not be taken out.
REMOVING THE INNER TUBE
1. Remove:
• Dust seal "1"
• Stopper ring "2"Using slotted-head screwdriver.
Take care not to scratch the inner
tube.
2. Remove:• Inner tube "1"
Oil seal removal steps:
a. Push in slowly "a" the inner tube just before it bottoms out and then
pull it back quickly "b".
b. Repeat this step until the inner tube can be pulled out from the
outer tube.
REMOVING THE BASE VALVE
1. Remove:• Base valve "1"
From damper assembly "2".
Hold the damper assembly with the
cap bolt ring wrench "3" and use the
cap bolt wrench "4" to remove the
base valve.
CHECKING THE DAMPER
ASSEMBLY
1. Inspect:• Damper assembly "1"Bend/damage
→ Replace.
• O-ring "2"
Wear/damage
→ Replace.
The front fork with a built-in piston
rod has a very sophisticated inter-
nal construction and is particularly
sensitive to foreign material.
Use enough care not to allow any
foreign material to come in when
the oil is replaced or when the
front fork is disassembled and re-
assembled.Cap bolt ring wrench: YM-01501/90890-01501
Cap bolt ring wrench:YM-01501/90890-01501
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench:
YM-01501/90890-01501

5-19
FRONT FORK
CHECKING THE BASE VALVE
1. Inspect:• Base valve "1"Wear/damage
→Replace.
Contamination
→Clean.
• O-ring "2" Wear/damage
→Replace.
• Piston metal "3" Wear/damage
→Replace.
• Spring "4"
Damage/fatigue
→Replace base
valve.
• Air bleed screw "5"
Wear/damage
→Replace.
CHECKING THE COLLAR
1. Inspect: • Piston metal "1"Wear/damage
→Replace.
CHECKING THE FORK SPRING
1. Measure: • Fork spring free length "a"Out of specification
→Replace.
CHECKING THE INNER TUBE
1. Inspect: • Inner tube surface "a"Score marks
→Repair or replace.
Use #1,000 grit wet sandpaper.
Damaged oil lock piece
→Re-
place.
• Inner tube bends
Out 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
inner tube as this may dangerous-
ly weaken the tube.
CHECKING THE OUTER TUBE
1. Inspect:
• Outer tube "1"
Score marks/wear/damage
→Re-
place.
CHECKING THE ADJUSTER
1. Inspect: • Adjuster "1"
• O-ring "2"Wear/damage
→Replace.
ASSEMBLING THE FRONT FORK
1. Wash the all parts in a clean sol- vent.
2. Stretch the damper assembly ful- ly.
3. Fill: • Front fork oil "1"To damper assembly.
• Be sure to use recommended fork oil. If other oils are used,
they may have an excessively ad-
verse effect on the front fork per-
formance.
• Never allow foreign materials to enter the front fork.
4. After filling, pump the damper as- sembly "1" slowly up and down
(about 200 mm (7.9 in) stroke)
several times to bleed the damper
assembly of air.
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, re-
peat the steps 2 to 4.
5. Measure:
• Oil level (left and right) "a"Out of specification
→ Adjust.
Fork spring free length:
454 mm (17.9 in)
: 449 mm (17.7
in)
Inner tube bending limit:0.2 mm (0.008 in)
Recommended oil: Suspension oil "S1"
Oil capacity: 199 cm
3 (7.00 Imp oz,
6.73 US oz)
Standard oil level: 145-148 mm (5.71-5.83
in)
From top of fully
stretched damper as-
sembly.

5-20
FRONT FORK
6. Tighten:• Locknut "1"
Fully finger tighten the locknut onto
the damper assembly.
7. Loosen:• Compression damping adjuster "1"
• Loosen the compression damping adjuster finger tight.
• Record the set position of the ad- juster (the amount of turning out the
fully turned in position).
8. Install:• Base valve "1"To damper assembly "2".
First bring the damper rod pressure to
a maximum. Then install the base
valve while releasing the damper rod
pressure.
9. Check:• Damper assemblyNot fully stretched
→ Repeat the
steps 2 to 8.
10. Tighten: • Base valve "1"
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.
11. After filling, pump the damper as-
sembly "1" slowly up and down
more than 10 times to distribute
the fork oil.
12. While protecting the damper as- sembly "1" with a rag and com-
pressing fully, allow excessive oil
to overflow on the base valve
side.
Take care not to damage the damp-
er assembly.
13. Allow the overflowing oil to es-
cape at the hole "a" in the damper
assembly.
14. Check: • Damper assembly smooth move-
ment
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".
• Apply the fork oil on the inner tube.
• When installing the oil seal, use vi-
nyl seat "a" with fork oil applied to
protect the oil seal lip.
• Install the oil seal with its manufac- ture's marks or number facing the
axle holder side.
16. Install:• Piston metal "1"
Install the piston metal onto the slot
on inner tube.
Base valve: 29 Nm (2.9 m•kg, 21 ft•
lb)
Cap bolt wrench:
YM-01500/90890-01500
Cap bolt ring wrench: YM-01501/90890-01501