2008 YAMAHA WR 250F Owners Manual

3-10
ENGINE
Handling notes of coolant:
The coolant is harmful so it should be
handled with special care.
• When coolant splashes to your eye.
Thoroughly wash your eye with
water and see your doctor.
• When coolant splashes to your clothes.
Quickly wash it away with water
and then with soap.
• When coolant is swallowed. Quickly make him vomit and take
him to a doctor.
9. Install:• Radiator cap
Start the engine and warm it up
for a several minutes.
10. Check:
• Coolant levelCoolant level low →Add coolant.
CHECKING THE RADIATOR CAP
1. Inspect: • Seal (radiator cap) "1"
• Valve and valve seat "2"Crack/damage →Replace.
Exist fur deposits "3" →Clean or
replace.
CHECKING THE RADIATOR CAP
OPENING PRESSURE
1. Attach: • Radiator cap tester "1" and adapt-er "2"
Apply water on the radiator cap seal.
3. Radiator cap
2. Apply the specified pressure.
3. Inspect: •PressureImpossible to maintain the speci-
fied pressure for 10 seconds →
Replace.
CHECKING THE COOLING
SYSTEM
1. Inspect: • Coolant level
2. Attach: • Radiator cap tester "1" and adapt-
er "2"
3. Apply the specified pressure.
• Do not apply pressure more than specified pressure.
• Radiator should be filled fully.
4. Inspect: •PressureImpossible to maintain the speci-
fied pressure for 10 seconds →
Repair.
• Radiator "1"
• Radiator hose joint "2" Coolant leakage →Repair or re-
place.
• Radiator hose "3" Swelling →Replace. ADJUSTING THE CLUTCH CABLE
FREE PLAY
1. Check:
• Clutch lever free play "a"Out of specification →Adjust.
2. Adjust: • Clutch lever free play
Clutch lever free play adjustment
steps:
a. Loosen the locknuts "1".
b. Adjust the free play by changing their tightening position.
c. Tighten the locknuts.
• Make minute adjustment on the le- ver side using the adjuster "2".
• After adjustment, check proper op- eration of clutch lever.
ADJUSTING THE THROTTLE
CABLE FREE PLAY
1. Check:
• Throttle grip free play "a"Out of specification →Adjust.
Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter: YU-33984/90890-01352
Radiator cap opening
pressure:110 kPa (1.1 kg/cm
2,
15.6 psi)
Radiator cap tester: YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352
Standard pressure: 180 kPa (1.8 kg/cm
2,
25.6 psi)
Clutch lever free play "a"
: 8–13 mm (0.31–0.51 in)
Locknut: 7 Nm (0.7 m•kg, 5.1
ft•lb)
Throttle grip free play
"a": 3–5 mm (0.12–0.20 in)

3-11
ENGINE
2. Adjust:• Throttle grip free play
Throttle grip free play adjustment
steps:
a. Slide the adjuster cover.
b. Loosen the locknut "1".
c. Turn the adjuster "2" until the
specified free play is obtained.
d. Tighten the locknut.
Before adjusting the throttle cable
free play, the engine idle speed
should be adjusted.
After adjusting the throttle cable
free play, start the engine and turn
the handlebar to right and left and
make sure that the engine idling
does not run faster.
LUBRICATING THE THROTTLE
1. Remove: • Cover (throttle cable cap) "1"
• Cover (grip cap) "2"
• Throttle grip cap "3"
2. Apply: • Lithium soap base grease
On the throttle cable end "a". 3. Install:
• Throttle grip cap
• Screw (throttle grip cap)
• Cover (grip cap)
• Cover (throttle cable cap)
ADJUSTING THE HOT STARTER
LEVER FREE PLAY
1. Check: • Hot starter lever free play "a"Out of specification →Adjust.
2. Adjust: • Hot starter lever free play
Hot starter lever free play adjust-
ment steps:
a. Loosen the locknut "1".
b. Turn the adjuster "2" until free
play "a" is within the specified lim-
its.
c. Tighten the locknut.
After adjustment, check proper oper-
ation of hot starter.
CLEANING THE AIR FILTER
ELEMENT
Proper air filter maintenance is the
biggest key to preventing premature
engine wear and damage.
Never run the engine without the
air filter element in place; this
would allow dirt and dust to enter
the engine and cause rapid wear
and possible engine damage.
1. Open the air filter case cover "1"
Loosen the quick screw "2" and pull
on it to open the air filter case cover.
2. Unhook: •Binder "1"
3. Remove: • Air filter element "1"
• Air filter guide "2"
4. Clean: • Air filter element
Clean them with solvent.
After cleaning, remo ve the remaining
solvent by squeezing the element.
• Do not twist the element when squeezing the element.
• Leaving too much of solvent in
the element may result in poor
starting.
Locknut: 4 Nm (0.4 m•kg, 2.9
ft•lb)
Screw (throttle grip cap):4 Nm (0.4 m•kg, 2.9
ft•lb)
Hot starter lever free play
"a": 3–6 mm (0.12–0.24 in)
Locknut: 4 Nm (0.4 m•kg, 2.9
ft•lb)

3-12
ENGINE
5. Inspect:• Air filter elementDamage →Replace.
6. Apply:
• Foam-air-filter oil or equivalent oil to the element
• Squeeze out the excess oil. Ele-ment should be wet but not drip-
ping.
• Wipe off the oil left on the element surface using a clean dry cloth. (Ex-
cess oil in the element may ad-
versely affect engine starting.)
7. Install:• Air filter guide "1"
• Align the projection "a" on filter guide with the hole "b" in air filter el-
ement.
• Apply the lithium soap base grease on the matching surface "c" on air
filter element.
8. Install:
• Air filter element "1"
Align the projection "a" on filter guide
with the hole "b" in air filter case.
9. Hook:•Binder "1"
Hook the binder "1" so that it contacts
the filter guide projections "a".
CHECKING THE ENGINE OIL
LEVEL
1. Start the engine, warm it up for several minutes, and then turn off
the engine and wait for five min-
utes.
2. Place the machine on a level
place and hold it up on upright po-
sition by placing the suitable
stand under the engine.
3. Inspect: • Oil levelOil should be up to the full level in
the check window "1".
Level check window is not full. →
Add 0.2 L (0.18 Imp qt, 0.21 US
qt) of oil.
(For USA and CDN)
• Do not add any chemical addi- tives. Engine oil also lubricates
the clutch and additives could
cause clutch slippage.
• Do not allow foreign material to enter the crankcase.
(Except for USA and CDN)
• Do not add any chemical addi-tives or use oils with a grade of
CD "a" or higher.
• Do not use oils labeled "ENERGY CONSERVING II" "b" or higher.
Engine oil also lubricates the
clutch and additives could cause
clutch slippage.
• Do not allow foreign material to enter the crankcase.
4. Install:
• Oil tank cap
5. Start the engine and let it warm up for several minutes.
6. Turn off the engine and inspect the oil level once again.
Wait a few minutes until the oil settles
before inspecting the oil level.
CHANGING THE ENGINE OIL
1. Start the engine and warm it up for several minutes, and then turn
off the engine and wait for five
minute.
2. Place the machine on a level place and hold it on upright posi-
tion by placing the suitable stand
under the engine.
3. Place a suitable container under
the engine.
Recommended oil:Yamalube 4,
SAE10W30 or
SAE20W40
Yamalube 4-R,
SAE10W50
API service SG type or
higher, JASO standard
MA
Recommended oil: SAE10W30,
SAE10W40,
SAE15W40, SAE20W40
or SAE20W50
API service SG type or
higher, JASO standard
MA

3-13
ENGINE
4. Remove:• Engine guard "1"
• Bolt (oil tank) "2"
• Washer "3"
• Oil filler cap "4"
• Oil tank drain bolt "5"
• Crankcase oil drain bolt "6"
• Oil filter element drain bolt "7"Drain the crankcase and oil tank
of its oil.
5. Remove: • Oil hose clamp "1"
• Bolt (oil hose)
• Oil hose "2"
• Oil strainer "3"
6. Inspect: • Oil strainerClogged →Blow.
7. If the oil filter is to be replaced dur-
ing this oil change, remove the fol-
lowing parts and reinstall them.
Replacement steps:
a. Remove the oil filter element cov-er "1" and oil filter element "2".
b. Check the O-rings "3", if cracked or damaged, replace them with a
new one.
c. Install the oil filter element and oil filter element cover.
8. Install:• O-ring "1"
• Oil strainer "2"
• Oil hose
• Bolt (oil hose)
• Oil hose clamp
9. Install: • Copper washer
• Oil filter element drain bolt
• Crankcase oil drain bolt
• Oil tank drain bolt
• Engine guard 10. Fill:
• Engine oil
11. Check: • Oil leakage
12. Install: • Oil filler cap
• Washer (oil tank)
• Bolt (oil tank)
13. Check: • Engine oil level
CHECKING THE OIL PRESSURE
1. Check: • Oil pressure
Checking steps:
a. Slightly loosen the oil pressure check bolt "1".
b. Start the engine and keep it idling
until oil starts to seep from the oil
pressure check bolt. If no oil
comes out after one minute, turn
the engine off so it will not seize.
c. Check oil passages and oil pump for damage or leakage.
d. Start the engine after solving the problem(s) and recheck the oil
pressure.
e. Tighten the oil pressure check bolt.
Oil filter element cover:10 Nm (1.0 m•kg, 7.2
ft•lb)
Oil strainer: 9 Nm (0.9 m•kg, 6.5
ft•lb)
Bolt (oil hose): 8 Nm (0.8 m•kg, 5.8
ft•lb)
Oil hose clamp: 2 Nm (0.2 m•kg, 1.4
ft•lb)
Oil filter element drain
bolt: 10 Nm (1.0 m•kg, 7.2
ft•lb)
Crankcase oil drain bolt: 20 Nm (2.0 m•kg, 14
ft•lb)
Oil tank drain bolt: 18 Nm (1.8 m•kg, 13
ft•lb)
Engine guard: 7 Nm (0.7 m•kg, 5.1
ft•lb)
Oil quantity: Periodic oil change:1.1 L (0.97 Imp qt, 1.16
US qt)
With oil filter replace-
ment:
1.2 L (1.06 Imp qt, 1.27
US qt)
Total amount:
1.4 L (1.23 Imp qt, 1.48
US qt)
Bolt (oil tank): 7 Nm (0.7 m•kg, 5.1
ft•lb)
Oil pressure check bolt: 10 Nm (1.0 m•kg, 7.2
ft•lb)

3-14
ENGINE
ADJUSTING THE PILOT SCREW
1. Adjust:• Pilot screw "1"
Adjustment steps:
To optimize the fuel flow at a smaller
throttle opening, each machine's pilot
screw has been individually set at the
factory. Before adjusting the pilot
screw, turn it in fully and count the
number of turns. Record this number
as the factory-set number of turns
out.
a. Turn in the pilot screw until it is
lightly seated.
b. Turn out the pilot screw by the factory-set number of turns.
ADJUSTING THE ENGINE IDLING
SPEED
1. Start the engine and thoroughly warm it up.
2. Adjust: • Engine idling speed
Adjustment steps:
a. Turn the throttle stop screw "1"
until the specified engine idling
speed.
Using a digital engine tachometer for
idle speed adjustment, detect the en-
gine idling speed by bringing the
sensing element "c" of the engine ta-
chometer close to the ignition coil "2".
ADJUSTING THE VALVE
CLEARANCE
• The valve clearance should be ad0justed when the engine is cool
to the touch.
• The piston must be at Top Dead Center (T.D.C.) on compression
stroke to check or adjust the valve
clearance.
1. Remove:
•Seat
•Fuel tankRefer to "REMOVING THE SEAT,
FUEL TANK AND SIDE COV-
ERS" section.
2. Drain:
• CoolantRefer to "CHANGING THE
COOLANT" section.
3. Remove: • Right radiatorRefer to "RADIATOR" section in
the CHAPTER 5.
• Carburetor Refer to "CARBU RETOR" section
in the CHAPTER 5.
• Spark plug
• Upper engine bracket
• Cylinder head cover Refer to "CAMSHAFTS" section
in the CHAPTER 5. 4. Remove:
• Timing mark accessing screw "1"
• Crankshaft end accessing screw "2"
• O-ring
5. Check: • Valve clearanceOut of specification →Adjust.
Checking steps:
a. Turn the crankshaft counterclock-
wise with a wrench.
b. Align the T.D.C. mark "a" on the
rotor with the align mark "b" on the
crankcase cover when piston is at
T.D.C. on compression stroke.
In order to be sure t hat the piston is at
Top Dead Center, the punch mark "c"
on the exhaust camshaft and the
punch mark "d" on the intake cam-
shaft must align with the cylinder
head surface, as shown in the illustra-
tion.
Pilot screw (example):
1-1/2 turns out
(For EUROPE)
To increase idle speed →Turn the
throttle stop screw "1" in "a".
To decrease idle speed →Turn the
throttle stop screw "1" out "b".
Engine idling speed:1,750–1,950 r/min
Valve clearance (cold):
Intake valve:0.10–0.15 mm
(0.0039–0.0059 in)
Exhaust valve: 0.17–0.22 mm
(0.0067–0.0087 in)

3-15
ENGINE
c. Measure the valve clearance "e" using a feeler gauge "1".
Record the measured reading if the
clearance is incorrect.
6. Adjust:• Valve clearance
Adjustment steps:
a. Remove the camshaft (intake and exhaust).
Refer to "CAMSHAFTS" section
in the CHAPTER 5.
b. Remove the valve lifters "1" and
the pads "2".
• Place a rag in the timing chain space to prevent pads from falling
into the crankcase.
• Identity each valve lifter and pad position very carefully so that they
can be reinstalled in their original
place.
c. Select the proper pad using the pad selecting table.
The thickness "a" of each pad is indi-
cated in hundredths of millimeters on
the pad upper surface.
d. Round off the last digit of the in-stalled pad number to the nearest
increment.
EXAMPLE:
Installed pad number = 148
Rounded off value = 150
Pads can only be selected in 0.05
mm increments.
e. Locate the rounded-off value and the measured valve clearance in
the chart "PAD SELECTION TA-
BLE". The field where these two
coordinates intersect shows the
new pad number to use.
Use the new pad number only as a
guide when verifying the valve clear-
ance adjustment.
f. Install the new pads "3" and the valve lifters "4".
• Apply the engine oil on the valve lift-
ers.
• Apply the molybdenum disulfide oil on the valve stem ends.
• Valve lifter must turn smoothly
when rotated with a finger.
• Be careful to reinstall valve lifters
and pads in their original place.
g. Install the camshafts (exhaust and intake).
Refer to "CAMSHAFTS" section
in the CHAPTER 5.
Pad range Pad Availabili-
ty: 25 incre- ments
No.
120– No.
240 1.20
mm– 2.40 mm Pads are avail-
able in 0.05 mm
increments
Last digit of pad number Rounded valve
0, 1 or 2 0
4, 5 or 6 5
8 or 9 10

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)