2010 YAMAHA WR 250F oil pressure

3-24
CHASSIS
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.
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 force
By 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.
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

4-5
CHASSIS
CHASSIS
SELECTION OF THE SECONDARY
REDUCTION RATIO (SPROCKET)
ondary gear reduction ratio>
• It is generally said that the second-ary gear ratio should be reduced for
a longer straight portion of a speed
course and should be increased for
a course with many corners. Actual-
ly, however, as the speed depends
on the ground condition of the day
of the ride, be su re to run through
the circuit to set the machine suit-
able for the entire course.
• In actuality, it is very difficult to
achieve settings suitable for the en-
tire course and some settings may
be sacrificed. Thus, the settings
should be matched to the portion of
the course that has the greatest ef-
fect on the ride result. In such a
case, run through the entire course
while making notes of lap times to
find the best balance; then, deter-
mine the secondary reduction ratio.
• If a course has a long straight por-
tion where a machine can run at
maximum speed, the machine is
generally set such that it can devel-
op its maximum revolutions toward
the end of the straight line, with care
taken to avoid the engine over-rev-
ving.
Riding technique varies from rider to
rider and the performance of a ma-
chine also vary fr om machine to ma-
chine. Therefore, do not imitate other
rider's settings from the beginning but
choose your own setting according to
the level of your riding technique.
DRIVE AND REAR WHEEL
SPROCKETS SETTING PARTS
TIRE PRESSURE
Tire pressure should be adjust to suit
the road surface condition of the cir-
cuit.
• Under a rainy, muddy, sandy, or slippery condition, the tire pressure
should be lower for a larger area of
contact with the road surface. • Under a stony or hard road condi-
tion, the tire pressure should be
higher to prevent a flat tire.
FRONT FORK SETTING
The front fork setting should be made
depending on the rider's feeling of an
actual run and the circuit conditions.
The front fork setting includes the fol-
lowing three factors:
1. Setting of air spring characteris- tics
• Change the fork oil level.
2. Setting of spring preload • Change the spring.
• Install the adjustment washer.
3. Setting of damping force • Change the compression damp-
ing.
• Change the rebound damping. The spring acts on the load and
the damping force acts on the
cushion travel speed.
CHANGE IN LEVEL AND
CHARACTERISTICS OF FORK OIL
Damping characteristic near the final
stroke can be changed by changing
the fork oil amount.
Adjust the oil level in 5 mm (0.2 in)
increments or decrements. Too
low oil level caus es the front fork
to produce a noise at full rebound
or the rider to feel some pressure
on his hands or body. Alternative-
ly, too high oil level will develop
unexpectedly early oil lock with
the consequent shorter front fork
travel and deteriorated perfor-
mance and characteristics. There-
fore, adjust the front fork within
the specified range.
Secondary reduction ratio =
Number of rear wheel sprocket
teeth/Number of drive sprocket
teeth
Standard secondary
reduction ratio 50/13
(3.846)
* 47/14
(3.357)
* For EUROPE
Part
name Size Part number
Drive
sprocket
"1" (STD) 13T 9383B-13218
** (STD) * 14T 9383B-14222
Rear
wheel
sprocket
"2" ** (STD) ** 47T 1C3-25447-00 48T 5GS-25448-50
* 48T 1C3-25448-00
* 49T 1C3-25449-00
(STD) 50T 5TJ-25450-80
* (STD) * 50T 1C3-25450-00 * 51T 1C3-25451-0052T 5TJ-25452-80
* 52T 1C3-25452-00
* For AUS and NZ
** For EUROPE
Standard tire pressure:100 kPa (1.0 kgf/cm
2,
15 psi)
Extent of adjustment: 60–80 kPa (0.6–0.8 kgf/
cm
2, 9.0–12 psi)
Extent of adjustment: 100–120 kPa (1.0–1.2
kgf/cm
2, 15–18 psi)
Standard oil level: 132 mm (5.20 in)
Extent of adjustment: 95–150 mm (3.74–5.91
in)
From top of outer tube
with inner tube and
damper rod fully com-
pressed without
spring.

5-29
CLUTCH
CLUTCH
REMOVING THE CLUTCHOrder Part name Q'ty Remarks Drain the engine oil. Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Brake pedal Refer to "ENGINE REMOVAL" section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Clutch spring 5
3 Pressure plate 1
4 Push rod 1 1
5 Circlip 1
6 Washer 1
7 Bearing 1
8Ball 1
9 Push rod 2 1
10 Friction plate 9
11 Clutch plate 8
12 Cushion spring 1
13 Seat plate 1

5-32
CLUTCH
INSTALLING THE CLUTCH
1. Install:• Primary driven gear "1"
• Thrust washer "2"
• Clutch boss "3"
Apply the engine oil on the primary
driven gear inner circumference.
2. Install:
• Lock washer "1"
• Nut (clutch boss) "2"
Use the clutch holding tool "3" to hold
the clutch boss.
A. For USA and CDN
B. Except for USA and CDN
3. Bend the lock washer "1" tab.
4. Install: • Seat plate "1"
• Cushion spring "2"
• Install the seat plate with its cham-fered portion "a" facing the clutch
boss "3".
• Install the seat plate so that it is not caught on the step "b".
• Install the cushion spring with the paint "c" facing out.
5. Install:
• Friction plate 1 "1"
• Clutch plate 1 "2"
• Friction plate 2 "3"
• Clutch plate 2 "4"
• Install the clutch plates and friction plates alternately on the clutch
boss, starting with a friction plate
and ending with a friction plate.
• Use the friction plates 1 for the first and final while paying attention to
the difference in surface pattern.
• Apply the engine oil on the friction plates and clutch plates.
• Unlike the clutch pl ate 2, the clutch
plate 1 has no surface gloss. Use
the clutch plate 1 for the first while
paying attention to the difference in
surface gloss.
6. Install:
•Bearing "1"
• Washer "2"
• Circlip "3" To push rod 1 "4".
Apply the engine oil on the bearing
and washer.
7. Install:• Push rod 2 "1"
•Ball "2"
• Push rod 1 "3"
Apply the engine oil on the push rod
1, 2 and ball.
8. Install:• Pressure plate "1"
9. Install: • Clutch spring "1"
• Bolt (clutch spring) "2"
Tighten the bolts in stage, using a
crisscross pattern.
Nut (clutch boss): 75 Nm (7.5 m•kg, 54
ft•lb)
Clutch holding tool: YM-91042/90890-04086
Bolt (clutch spring):10 Nm (1.0 m•kg, 7.2
ft•lb)

6-38
REAR SHOCK ABSORBER
HANDLING NOTE
• Support the machine securely so there is no danger of it falling
over.
• This rear shock absorber is pro-
vided with a separate type tank
filled with high-pressure nitro-
gen gas. To prevent the danger
of explosion, read and under-
stand the follow ing information
before handling the shock ab-
sorber. The manufacturer can
not be held responsible for prop-
erty damage or personal injury
that may result from improper
handling.
• Never tamper or attempt to dis-
assemble the cylinder or the
tank.
• Never throw the rear shock ab-
sorber into an open flame or
other high heat. The rear shock
absorber may explode as a re-
sult of nitrogen gas expansion
and/ or damage to the hose.
• Be careful not to damage any
part of the gas tank. A damaged
gas tank will impair the damp-
ing performance or cause a
malfunction.
• Take care not to scratch the
contact surface of the piston
rod with the cylinder; or oil
could leak out.
• Never attempt to remove the plug at the bottom of the nitro-
gen gas tank. It is very danger-
ous to remove the plug.
• When scrapping the rear shock absorber, follow the instruc-
tions on disposal.
NOTES ON DISPOSAL (YAMAHA
DEALERS ONLY)
Before disposing the rear shock ab-
sorber, be sure to extract the nitrogen
gas from valve "1". Wear eye protec-
tion to prevent eye damage from es-
caping gas and/or metal chips.
To dispose of a damaged or worn-
out rear shock absorber, take the
unit to your Yamaha dealer for this
disposal procedure.
REMOVING THE BEARING
1. Remove: • Stopper ring (upper bearing) "1"
Press in the bearing while pressing its
outer race and remove the stopper
ring.
2. Remove:• Upper bearing "1"
Remove the bearing by pressing its
outer race.
3. Remove:• Lower bearing "1"
Remove the bearing by pressing its
outer race.
CHECKING THE REAR SHOCK
ABSORBER
1. Inspect:• Damper rod "1"
Bends/damage →Replace rear
shock absorber assembly.
• Shock absorber "2"
Oil leaks →Replace rear shock
absorber assembly.
Gas leaks →Replace rear shock
absorber assembly.
• Spring "3" Damage →Replace spring.
Fatigue →Replace spring.
Move spring up and down.
• Spring guide "4"
Wear/damage →Replace spring
guide.
• Bearing "5"
Free play exists/unsmooth revolu-
tion/rust →Replace.
INSTALLING THE BEARING
1. Install: • Upper bearing "1"
Install the bearing parallel until the
stopper ring groove appears by
pressing its outer race.
Do not apply the grease on the
bearing outer race because it will
wear the rear shock absorber sur-
face on which the bearing is press
fitted.