YAMAHA WR 250F 2008 Manual PDF

3-16
ENGINE
INTAKE
EXHAUST

3-17
CHASSIS
CLEANING THE SPARK
ARRESTER (For USA)
• Be sure the exhaust pipe and si-lencer are cool before cleaning
the spark arrester.
• Do not start the engine when cleaning the exhaust system.
1. Remove:• Screw (silencer cap) "1"
2. Remove: • Bolt (spark arrester) "1"
3. Remove: • Tail pipe "1"
• Gasket (tail pipe) "2"
• Spark arrester "3"Pull the spark arrester out of the
silencer.
• Gasket (spark arrester) "4"
4. Clean: • Spark arrester
Tap the spark arrester lightly,
then use a wire brush to remove
any carbon deposits.
5. Install: • Gasket (spark arrester)
• Spark arresterInsert the spark arrester into the
silencer and align the bolt holes.
• Gasket (tail pipe)
• Bolt (spark arrester) 6. Install:
• Silencer cap
First tighten the two screws "a" locat-
ed horizontally apart, and then tighten
the others.
CHASSIS
BLEEDING THE HYDRAULIC
BRAKE SYSTEM
Bleed the brake system if:
• The system has been disassem-bled.
• A brake hose has been loosened
or removed.
• The brake fluid is very low.
• The brake operation is faulty.
A dangerous loss of braking per-
formance may occur if the brake
system is not properly bled.
1. Remove: • Brake master cylinder cap
• Diaphragm
• Reservoir float (front brake)
• Protector (rear brake)
2. Bleed: •Brake fluid
Air bleeding steps:
a. Add proper brake fluid to the res- ervoir.
b. Install the diaphragm. Be careful not to spill any fluid or allow the
reservoir to overflow.
c. Connect the clear plastic tube "2" tightly to the caliper bleed screw
"1". A. Front
B. Rear
d. Place the other end of the tube
into a container.
e. Slowly apply the brake lever or pedal several times.
f. Pull the lever in or push down on
the pedal. Hold the lever or pedal
in position.
g. Loosen the bleed screw and allow
the lever or pedal to travel to-
wards its limit.
h. Tighten the bleed screw when the
lever or pedal limit has been
reached; then release the lever or
pedal.
i. Repeat steps (e) to (h) until of the air bubbles have been removed
from the system.
If bleeding is difficult, it may be nec-
essary to let the brake fluid system
stabilize for a few hours. Repeat the
bleeding procedure when the tiny
bubbles in the system have disap-
peared.
j. Add brake fluid to the level line on the reservoir.
Check the operation of the brake
after bleeding the brake system.
3. Install:
• Protector (rear brake)
• Reservoir float (front brake)
• Diaphragm
• Brake master cylinder cap
ADJUSTING THE FRONT BRAKE
1. Check: • Brake lever position "a"
Bolt (spark arrester): 7 Nm (0.7 m•kg, 5.1
ft•lb)
Silencer cap:5 Nm (0.5 m•kg, 3.6
ft•lb)
Bleed screw:
6 Nm (0.6 m•kg, 4.3
ft•lb)
Brake lever position "a":
Standard posi- tion Extent of ad-
justment
95 mm (3.74 in) 76–97 mm
(2.99–3.82 in)

3-18
CHASSIS
2. Remove:• Brake lever cover
3. Adjust: • Brake lever position
Brake lever position adjustment
steps:
a. Loosen the locknut "1".
b. Turn the adjusting bolt "2" until the lever position "a" is within speci-
fied position.
c. Tighten the locknut.
Be sure to tighten the locknut, as it
will cause poor brake perfor-
mance.
4. Install: • Brake lever cover
ADJUSTING THE REAR BRAKE
1. Check: • Brake pedal height "a"Out of specification →Adjust.
2. Adjust: • Brake pedal height
Pedal height adjustment steps:
a. Loosen the locknut "1".
b. Turn the adjusting nut "2" until the
pedal height "a" is within specified
height.
c. Tighten the locknut.
• Adjust the pedal height between
the maximum "A" and the mini-
mum "B" as shown. (In this ad-
justment, the bolt "3" end "b"
should protrude out of the
threaded portion "4" but not be
less than 2 mm (0.08 in) "c" away
from the brake pedal "5").
• After the pedal height adjust- ment, make sure that the rear
brake does not drag.
CHECKING AND REPLACING THE
FRONT BRAKE PADS
1. Inspect:• Brake pad thickness "a"Out of specification →Replace as
a set.
2. Replace: •Brake pad
Brake pad replacement steps:
a. Remove the pad pin plug "1". b. Loosen the pad pin "2".
c. Remove the brake caliper "3"
from the front fork.
d. Remove the pad pin and brake pads "4".
e. Connect the transparent hose "5" to the bleed screw "6" and place
the suitable container under its
end.
f. Loosen the bleed screw and push the brake caliper piston in.
Do not reuse the drained brake flu-
id.
g. Tighten the bleed screw.
h. Install the brake pads "7" and pad pin.
• Install the brake pads with their pro-
jections "a" into the brake caliper re-
cesses "b".
• Temporarily tighten the pad pin at
this point.
Locknut: 5 Nm (0.5 m •kg, 3.6
ft•lb)
Brake pedal height "a": 10 mm (0.39 in)
Brake pad thickness:4.4 mm (0.17 in)
: 1.0 mm (0.04
in)
Bleed screw: 6 Nm (0.6 m•kg, 4.3
ft•lb)

3-19
CHASSIS
i. Install the brake caliper "8" and tighten the pad pin "9".
j. Install the pad pin plug "10".
3. Inspect: • Brake fluid levelRefer to "CHECKING THE
BRAKE FLUID LEVEL" section.
4. Check: • Brake lever operationA softy or spongy feeling →Bleed
brake system.
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion.
CHECKING AND REPLACING THE
REAR BRAKE PADS
1. Inspect: • Brake pad thickness "a"Out of specification →Replace as
a set. 2. Replace:
•Brake pad
Brake pad replacement steps:
a. Remove the protector "1" and pad
pin plug "2".
b. Loosen the pad pin "3".
c. Remove the rear wheel "4" and brake caliper "5".
Refer to "FRONT WHEEL AND
REAR WHEEL" section in the
CHAPTER 6.
d. Remove the pad pin "6" and brake pads "7".
e. Connect the transparent hose "8" to the bleed screw "9" and place
the suitable container under its
end.
f. Loosen the bleed screw and push the brake caliper piston in.
Do not reuse the drained brake flu-
id.
g. Tighten the bleed screw.
h. Install the brake pad "10" and pad pin "11".
• Install the brake pads with their pro-
jections "a" into the brake caliper re-
cesses "b".
• Temporarily tighten the pad pin at
this point.
i. Install the brake caliper "12" and rear wheel "13".
Refer to "FRONT WHEEL AND
REAR WHEEL" section in the
CHAPTER 6.
j. Tighten the pad pin "14".
k. Install the pad pin plug "15" and protector "16".
Bolt (brake caliper):
23 Nm (2.3 m•kg, 17
ft•lb)
Pad pin:
18 Nm (1.8 m•kg, 13
ft•lb)
Pad pin plug: 3 Nm (0.3 m•kg, 2.2
ft•lb)
Brake pad thickness: 6.4 mm (0.25 in)
: 1.0 mm (0.04
in)
Bleed screw:6 Nm (0.6 m•kg, 4.3
ft•lb)
Pad pin: 18 Nm (1.8 m•kg, 13
ft•lb)
Pad pin plug: 3 Nm (0.3 m•kg, 2.2
ft•lb)
Bolt (protector): 7 Nm (0.7 m•kg, 5.1
ft•lb)

3-20
CHASSIS
3. Inspect:• Brake fluid levelRefer to "CHECKING THE
BRAKE FLUID LEVEL" section.
4. Check: • Brake pedal operationA softy or spongy feeling →Bleed
brake system.
Refer to "BLEEDING THE HY-
DRAULIC BRAKE SYSTEM" sec-
tion.
CHECKING THE REAR BRAKE
PAD INSULATOR
1. Remove: • Brake pad
Refer to "CHECKING AND RE-
PLACING THE REAR BRAKE
PADS" section.
2. Inspect: • Rear brake pad insulator "1"Damage →Replace.
CHECKING THE BRAKE FLUID
LEVEL
1. Place the brake master cylinder so that its top is in a horizontal po-
sition.
2. Inspect:
• Brake fluid levelFluid at lower level →Fill up.
• Use only designated quality
brake fluid to avoid poor brake
performance.
• Refill with same type and brand of brake fluid; mixing fluids
could result in poor brake perfor-
mance.
• Be sure that water or other con- taminants do not enter master
cylinder when refilling.
• Clean up spilled fluid immediate- ly to avoid erosion of painted
surfaces or plastic parts.
a. Lower level
A. Front
B. Rear
CHECKING THE SPROCKET
1. Inspect: • Sprocket teeth "a"Excessive wear →Replace.
Replace the drive sprocket, rear
wheel sprocket and drive chain as a
set.
CHECKING THE DRIVE CHAIN
1. Measure:
• Drive chain length (15 links) "a"
Out of specification →Replace.
• While measuring the drive chain
length, push down on the drive
chain to increase its tension.
• Measure the length between drive chain roller "1" and "16" as shown.
• Perform this measurement at two or
three different places.
2. Remove:• Drive chain "1"
Remove the drive chain using a drive
chain cutter "2".
3. Clean:• Drive chain
Brush off as much dirt as possi-
ble. Then clean the drive chain
using the chain cleaner.
This machine has a drive chain
with small rubber O-rings "1" be-
tween the side plates. Steam
cleaning, high-p ressure washes,
certain solvent and kerosene can
damage these O-rings.
4. Inspect: • O-ring "1" (drive chain)Damage →Replace the drive
chain.
•Roller "2"
• Side plate "3"
Damage/wear →Replace the
drive chain.
5. Check: • Drive chain stiffness "a"Clean and oil the drive chain and
hold as illustrated.
Stiff →Replace the drive chain.
6. Install: • Chain joint "1"
• O-ring "2"
• Drive chain "3"
• Link plate "4"
Recommended brake flu-
id:
DOT #4
Drive chain length (15
links):: 239.3 mm
(9.42 in)

3-21
CHASSIS
When installing the drive chain, apply
the lithium soap base grease on the
chain joint and O-rings.
7. Install:• Link plate
• Press the link plate onto the chain
joint using a drive chain riveter "5".
• Rivet the end of the chain joint us- ing a drive chain riveter.
• After riveting the chain joint, make sure its movement is smooth.
8. Lubricate:• Drive chain
ADJUSTING THE DRIVE CHAIN
SLACK
1. Elevate the rear wheel by placing the suitable stand under the en-
gine.
2. Check: • Drive chain slack "a"Above the seal guard installation
bolt.
Out of specification →Adjust.
Before checking and/or adjusting, ro-
tate the rear wheel through several
revolutions and check the slack sev-
eral times to find the tightest point.
Check and/or adjust the drive chain
slack with the rear wheel in this "tight
chain" position.
3. Adjust:
• Drive chain slack
Drive chain slack adjustment
steps:
a. Loosen the axle nut "1" and lock- nuts "2".
b. Adjust the drive chain slack by turning the adjusters "3".
c. Turn each adjuster exactly the same amount to maintain correct
axle alignment. (There are marks
"a" on each side of the drive chain
puller alignment.)
Turn the adjuster so that the drive
chain is in line with the sprocket, as
viewed from the rear.
Too small drive chain slack will
overload the engine and other vital
parts; keep the slack within the
specified limits.
d. Tighten the axle nut while pushing down the drive chain. e. Tighten the locknuts.
CHECKING THE FRONT FORK
1. Inspect:
• Front fork smooth actionOperate the front brake and
stroke the front fork.
Unsmooth action/oil leakage →
Repair or replace.
CLEANING THE FRONT FORK OIL
SEAL AND DUST SEAL
1. Remove: •Protector
• Dust seal "1"
Use a thin screw driver, and be care-
ful not to damage the inner fork tube
and dust seal.
2. Clean:• Dust seal "a"
• Oil seal "b"
• Clean the dust seal and oil seal af-
ter every run.
• Apply the lithium soap base grease on the inner tube.
RELIEVING THE FRONT FORK
INTERNAL PRESSURE
If the front fork initial movement feels
stiff during a run, relieve the front fork
internal pressure.
Drive chain lubricant: SAE 10W-30 motor oil
or suitable chain lubri-
cants
Drive chain slack: 48–58 mm (1.9–2.3 in)
To tighten →Turn the adjuster "3"
counterclockwise.
To loosen →Turn the adjuster "3"
clockwise and push wheel for-
ward.
Axle nut:125 Nm (12.5 m•kg, 90
ft•lb)
Locknut: 19 Nm (1.9 m•kg, 13
ft•lb)

3-22
CHASSIS
1. Elevate the front wheel by placing a suitable stand under the engine.
2. Remove the air bleed screw "1" and release the internal pressure
from the front fork.
3. Install: • Air bleed screw
ADJUSTING THE FRONT FORK
REBOUND DAMPING FORCE
1. Adjust: • Rebound damping forceBy turning the adjuster "1".
• STANDARD POSITION: This is the position which is back
by the specific number of clicks
from the fully turned-in position.
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
Always adjust each front fork to
the same setting. Uneven adjust-
ment can cause poor handling and
loss of stability.
ADJUSTING THE FRONT FORK
COMPRESSION DAMPING FORCE
1. Remove:• Rubber cap
2. Adjust:
• Compression damping forceBy turning the adjuster "1".
• STANDARD POSITION: This is the position which is back
by the specific number of clicks
from the fully turned-in position.
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
Always adjust each front fork to
the same setting. Uneven adjust-
ment can cause poor handling and
loss of stability.
3. Install:• Rubber cap CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:
• Swingarm smooth action
Abnormal noise/unsmooth action
→ Grease the pivoting points or
repair the pivoting points.
Damage/oil leakage →Replace.
ADJUSTING THE REAR SHOCK
ABSORBER SPRING PRELOAD
1. Elevate the rear wheel by placing the suitable stand under the en-
gine.
2. Remove:
• Rear frame
3. Loosen: • Locknut "1"
4. Adjust: • Spring preloadBy turning the adjuster "2".
Air bleed screw:
1 Nm (0.1 m•kg, 0.7
ft•lb)
Stiffer "a" →Increase the re-
bound damping force. (Turn
the adjuster "1" in.)
Softer "b" →Decrease the re-
bound damping force. (Turn
the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
Fully turned in
position 20 clicks out
(from maximum
position)
Standard position: 9 clicks out
Stiffer "a" →Increase the com-
pression damping force. (Turn
the adjuster "1" in.)
Softer "b" →Decrease the com-
pression damping force. (Turn
the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
Fully turned in
position 20 clicks out
(from maximum
position)
Standard position: 10 clicks out
* 11 clicks out
* Except for USA and CDN
Stiffer →Increase the spring pre-
load. (Turn the adjuster "2" in.)
Softer →Decrease the spring pre-
load. (Turn the adjuster "2"
out.)
Spring length (installed)
"a":
Standard length Extent of ad-
justment
249 mm (9.80
in)
* 245.0 mm
(9.65 in)
** 248.5 mm
(9.78 in) 238.5–258.5
mm (9.39–10.18
in)
* For AUS, NZ and ZA
** For EUROPE

3-23
CHASSIS
• Be sure to remove all dirt and mud from around the locknut and adjust-
er before adjustment.
• The length of the spring (installed) changes 1.5 mm (0.06 in) per turn
of the adjuster.
Never attempt to turn the adjuster
beyond the maximum or minimum
setting.
5. Tighten:
•Locknut
6. Install: • Rear frame (upper)
• Rear frame (lower)
ADJUSTING THE REAR SHOCK
ABSORBER REBOUND DAMPING
FORCE
1. Adjust: • Rebound damping forceBy turning the adjuster "1". • STANDARD POSITION:
This is the position which is back
by the specific number of clicks
from the fully turned-in position.
(Which align the punch mark "a"
on the adjuster with the punch
mark "b" on the bracket.)
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
ADJUSTING THE REAR SHOCK
ABSORBER LOW COMPRESSION
DAMPING FORCE
1. Adjust:• Low compression damping forceBy turning the adjuster "1".
• STANDARD POSITION: This is the position which is back
by the specific number of clicks
from the fully turned-in position.
(Which align the punch mark "a"
on the adjuster with the punch
mark "b" on the high compression
damping adjuster.)
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
ADJUSTING THE REAR SHOCK
ABSORBER HIGH COMPRESSION
DAMPING FORCE
1. Adjust:• High compression damping forceBy turning the adjuster "1".
• STANDARD POSITION: This is the position which is back
by the specific number of turns
from the fully turned-in position.
(Which align the punch mark "a"
on the adjuster with the punch
mark "b" on the adjuster body.)
Rear frame (upper):
38 Nm (3.8 m•kg, 27
ft•lb)
Rear frame (lower): 32 Nm (3.2 m•kg, 23
ft•lb)
Stiffer "a" →Increase the re-
bound damping force. (Turn
the adjuster "1" in.)
Softer "b" →Decrease the re-
bound damping force. (Turn
the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
Fully turned in
position 20 clicks out
(from maximum
position)
Standard position:
About 11 clicks out
Stiffer "a" →Increase the low
compression damping force.
(Turn the adjuster "1" in.)
Softer "b" →Decrease the low
compression damping force.
(Turn the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
Fully turned in
position 20 clicks out
(from maximum
position)
Standard position:
About 12 clicks out
* About 13 clicks out
* For AUS, NZ and ZA
Stiffer "a" →Increase the high
compression damping force.
(Turn the adjuster "1" in.)
Softer "b" →Decrease the high
compression damping force.
(Turn the adjuster "1" out.)
Extent of adjustment:
Maximum Minimum
Fully turned in
position 2 turns out
(from maximum
position)
Standard position: About 1-1/8 turns out
* About 1-1/4 turns out
* For EUROPE

3-24
CHASSIS
Do not force the adjuster past the
minimum or maximum extent of
adjustment. The adjuster may be
damaged.
CHECKING THE TIRE PRESSURE
1. Measure:• Tire pressure
Out of specification →Adjust.
• Check the tire while it is cold.
• Loose bead stoppers allow the tire
to slip off its position on the rim
when the tire pressure is low.
• A tilted tire valve stem indicates that
the tire slips off its position on the
rim.
• If the tire valve st em is found tilted,
the tire is considered to be slipping
off its position. Correct the tire posi-
tion.
CHECKING AND TIGHTENING THE
SPOKES
1. Inspect: • Spokes "1"Bend/damage →Replace.
Loose spoke →Retighten.
2. Tighten: • Spokes
Be sure to retighten these spokes be-
fore and after break-in. After a prac-
tice or a race check spokes for
looseness.
CHECKING THE WHEELS
1. Inspect:
• Wheel runoutElevate the wheel and turn it.
Abnormal runout → Replace.
2. Inspect: • Bearing free playExist play →Replace.
CHECKING AND ADJUSTING THE
STEERING HEAD
1. Elevate the front wheel by placing a suitable stand under the engine.
2. Check: • Steering stemGrasp the bottom of the forks and
gently rock the fork assembly
back and forth.
Free play →Adjust steering head.
3. Check: • Steering smooth actionTurn the handlebar lock to lock.
Unsmooth action →Adjust steer-
ing ring nut. 4. Adjust:
• Steering ring nut
Steering ring nut adjustment
steps:
a. Remove the headlight.
b. Remove the handlebar and upper bracket.
c. Loosen the steering ring nut "1" using the steering nut wrench "2".
d. Tighten the steering ring nut "3" using steering nut wrench "4".
• Apply the lithium soap base grease
on the thread of the steering stem.
• Set the torque wrench to the steer- ing nut wrench so that they form a
right angle.
e. Loosen the steering ring nut one turn.
f. Retighten the steering ring nut us- ing the steering nut wrench.
Avoid over-tightening.
Standard tire pressure:100 kPa (1.0 kgf/cm2,
15 psi)
Spokes: 3 Nm (0.3 m•kg, 2.2
ft•lb)
Steering nut wrench:YU-33975/90890-01403
Steering nut wrench: YU-33975/90890-01403
Steering ring nut (initial
tightening): 38 Nm (3.8 m•kg, 27
ft•lb)
Steering ring nut (final
tightening): 7 Nm (0.7 m•kg, 5.1
ft•lb)

3-25
CHASSIS
g. 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.
h. Install the washer "5", collar "6", upper bracket "7", washer "8",
steering stem nut "9", handlebar
"10", handlebar upper holder "11"
and headlight "12".
• Install the collar "6" with the larger
inside diameter facing downward.
• The handlebar upper holder should be installed with the punched mark
"a" forward.
• Install the handlebar so that the marks "b" are in place on both
sides.
• Install the handlebar so that the pro- jection "c" of the handlebar upper
holder is positioned at the mark on
the handlebar as shown.
• Insert the end of the fuel breather
hose "13" into the hole in the steer-
ing stem.
First tighten the bolts on the front
side of the handlebar upper holder,
and then tighten the bolts on the
rear side.
Steering stem nut: 145 Nm (14.5 m•kg, 105
ft•lb)
Handlebar upper holder:
28 Nm (2.8 m•kg, 20
ft•lb)
Pinch bolt (upper brack-
et): 21 Nm (2.1 m•kg, 15
ft•lb)
Headlight: 7 Nm (0.7 m•kg, 5.1
ft•lb)