radiator cap YAMAHA YZ250F 2008 Owners Manual

1-1
DESCRIPTION
GENERAL INFORMATION
DESCRIPTION
• The machine you have purchased may differ slightly from those shown in the following.
• Designs and specifications are subject to change without notice.
1. Clutch lever
2. Hot starter lever
3. Front brake lever
4. Throttle grip
5. Radiator cap
6. Fuel tank cap
7. Engine stop switch
8. Kickstarter crank
9. Fuel tank
10. Radiator
11. Coolant drain bolt
12. Rear brake pedal
13. Valve joint14. Fuel cock
15. Cold starter knob
16. Drive chain
17. Air filter
18. Oil level check window
19. Shift pedal
20. Front fork
1

1-5
SPECIAL TOOLS
Radiator cap tester
YU-24460-01, 90890-01325
Radiator cap tester adapter
YU-33984, 90890-01352These tools are used for checking
the cooling system.
Steering nut wrench
YU-33975, 90890-01403 This tool is used when tighten the
steering ring nut to specification.
Cap bolt wrench
YM-01500, 90890-01500 This tool is used to loosen or tighten
the base valve.
Cap bolt ring wrench
YM-01501, 90890-01501 This tool is used to loosen or tighten
the damper assembly.
Fork seal driver
YM-A0948, 90890-01502 This tool is used when install the fork
oil seal.
Pocket tester
YU-3112-C, 90890-03112 Use this tool to inspect the coil resis-
tance, output voltage and amper-
age.
Tool name/Part number
How to useIllustration

2-8
MAINTENANCE SPECIFICATIONS
CHASSISHeight
240 mm (9.4 in)----
Thickness 22 mm (0.9 in)----
Radiator cap opening pressure 110 kPa (1.1 kg/cm
2, 15.6 psi)----
Radiator capacity (total) 0.58 L (0.51 Imp qt, 0.61 US qt)----
Water pump Type Single-suction centrifugal pump----
Item
StandardLimit
Item StandardLimit
Steering system: Steering bearing type Taper roller bearing----
Front suspension: Front fork travel 300 mm (11.8 in)----
Fork spring free length 454 mm (17.9 in)449 mm (17.7
in)
Spring rate, STD K = 4.4 N/mm (0.449 kg/mm, 25.1 lb/in)----
Optional spring Yes----
Oil capacity 521 cm
3 (18.3 lmp oz, 17.6 US oz)----
Oil grade Suspension oil "S1"----
Inner tube outer diameter 48 mm (1.89 in)----
Front fork top end 5 mm (0.20 in)----
Rear suspension: USA, CDN, AUS, NZ,
ZA EUROPE
Shock absorber travel 131.5 mm (5.18 in)
←----
Spring free length Approx.275 mm (10.83 in)
←----
Fitting length One I.D. mark 268 mm (10.55 in) 262 mm (10.31 in) ----
Two I.D. marks 274 mm (10.79 in) 268 mm (10.55 in) ----
Three I.D. marks 265.5 mm (10.45 in) 259.5 mm (10.22 in) ----
One I.D. mark 255.5–273.5 mm (10.06–10.77 in)
←----
Two I.D. marks 261.5–279.5 mm
(10.30–11.00 in)
←----
Three I.D. marks 253.0–271.0 mm (9.96–
10.67 in)
←----
Spring rate, STD K = 52.0 N/mm (5.30 kg/ mm, 296.8 lb/in)
←----
Optional spring Yes
←----
Enclosed gas pressure 1,000 kPa (10 kg/cm
2,
142 psi)←----
Swingarm: Swingarm free play limitEnd ---- 1.0 mm (0.04 in)
Wheel: Front wheel type Spoke wheel----

2-10
TIGHTENING TORQUES
TIGHTENING TORQUES
ENGINE
△- marked portion shall be checked for torque tightening after break-in or before each race.
Pickup coil resistance (color)248–372 Ωat 20 °C (68 °F) (White–Red) ----
CDI unit-model/manufacturer 5XC-L0/YAMAHA (For USA and CDN) ----
5XC-M0/YAMAHA (For EUROPE, AUS,
NZ and ZA) ----
Ignition coil: Model/manufacturer 5UL-10/DENSO----
Minimum spark gap 6 mm (0.24 in)----
Primary coil resistance 0.08–0.10
Ωat 20 °C (68 °F)----
Secondary coil resistance 4.6–6.8 k
Ωat 20 °C (68 °F)----
Item
StandardLimit
Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb
Spark plug M10S × 1.0 1 13 1.3 9.4
Camshaft cap M6 × 1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12 × 1.0 1 28 2.8 20
Cylinder head (stud bolt) M6 × 1.0 2 7 0.7 5.1
Cylinder head (stud bolt) M8 × 1.25 1 15 1.5 11
Cylinder head (bolt) M9 × 1.25 4 38 3.8 27
Cylinder head (nut) M6 × 1.0 2 10 1.0 7.2
Cylinder head cover M6 × 1.0 2 10 1.0 7.2
Cylinder M6 × 1.0 1 10 1.0 7.2
Balancer weight M6 × 1.0 2 10 1.0 7.2
Balancer shaft driven gear M14 × 1.0 1 50 5.0 36
Timing chain guide (intake side) M6 × 1.0 2 10 1.0 7.2
Timing chain tensioner M6 × 1.0 2 10 1.0 7.2
Timing chain tensioner cap bolt M6 × 1.0 1 7 0.7 5.1
Impeller M8 × 1.25 1 14 1.4 10
Radiator hose clamp M6 × 1.0 10 2 0.2 1.4
Coolant drain bolt M6 × 1.0 1 10 1.0 7.2
Water pump housing M6 × 1.0 4 10 1.0 7.2
Radiator M6 × 1.0 6 10 1.0 7.2
Radiator pipe M6 × 1.0 1 10 1.0 7.2
Oil pump cover M4 × 0.7 1 2 0.2 1.4
Oil pump M6 × 1.0 3 10 1.0 7.2
Oil filter element drain bolt M6 × 1.0 1 10 1.0 7.2
Oil filter element cover M6 × 1.0 2 10 1.0 7.2
Oil strainer (crankcase) M6 × 1.0 2 10 1.0 7.2
Oil delivery pipe 1 (M10) M10 × 1.25 1 20 2.0 14
Oil delivery pipe 1 (M8) M8 × 1.25 2 18 1.8 13
Oil hose M6 × 1.0 2 8 0.8 5.8
△Oil hose clamp —1 2 0.2 1.4
Oil strainer (oil tank) M6 × 1.0 1 9 0.9 6.5

3-2
MAINTENANCE INTERVALS
CYLINDERInspect and clean
●Inspect score marks.
Replace
●Inspect wear.
CLUTCH Inspect and adjust
●●Inspect housing, friction plate, clutch
plate and spring.
Replace
●
TRANSMISSION Inspect
●
Replace bearing●
SHIFT FORK, SHIFT CAM,
GUIDE BARInspect
●Inspect wear.
ROTOR NUT Retighten
●●
EXHAUST PIPE, SILENCER,
PROTECTORInspect and retighten
●●
Clean●
Replace●* Whichever comes first
CRANK Inspect and clean
●●
CARBURETORInspect, adjust and clean
●●
SPARK PLUGInspect and clean
●●
Replace●
DRIVE CHAIN Use chain lube.
Lubricate, slack, alignment
●●Chain slack: 48–58 mm (1.9–2.3 in)
Replace
●
COOLING SYSTEM Check coolant level and leakage
●●
Check radiator cap operation●
Replace coolant●Every two years
Inspect hoses
●
OUTSIDE NUTS AND BOLTS Retighten
●●Refer to "STARTING AND BREAK-
IN" section in the CHAPTER 1.
AIR FILTER Clean and lubricate
●●Use foam air-filter oil or equivalent oil.
Replace
●
OIL FILTER Replace
●●
Item After
break-
in Every
race
Every third
(or 500 km) Every
fifth (or 1,000 km)
As re-
quired Remarks

3-5
PRE-OPERATION INSPECTION AND MAINTENANCE
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating condition.
Before using this machine, check the following points.
GENERAL INSPECTION AND MAINTENANCEItem RoutinePage
Coolant Check that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage. P.3-6 – 7
Fuel Check that a fresh gasoline is filled in the fuel tank. Check the fuel
line for leakage. P.1-8 – 9
Engine oil Check that the oil level is correct. Check the crankcase and oil line
for leakage. P.3-8 – 10
Gear shifter and clutch Check that gears can be shifted correctly in order and that the
clutch operates smoothly. P.3-7
Throttle grip/Housing Check that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary. P.3-7 – 8
Brakes Check the play of front brake and effect of front and rear brake. P.3-14 – 16
Drive chain Check drive chain slack and alignment. Check that the drive chain
is lubricated properly. P.3-17
Wheels Check for excessive wear and tire pressure. Check for loose
spokes and have no excessive play. P.3-20
Steering Check that the handlebar can be turned smoothly and have no ex-
cessive play. P.3-20 – 21
Front forks and rear shock
absorber Check that they operate smoothly and there is no oil leakage.
P.3-18 – 20
Cables (wires) Check that the clutch and throttle cables move smoothly. Check
that they are not caught when the handlebars are turned or when
the front forks travel up and down.
—
Exhaust pipe Check that the exhaust pipe is tightly mounted and has no cracks. P.4-3 – 4
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-16 – 17
Lubrication Check for smooth operation. Lubricate if necessary. P.3-22
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-11
Lead connectors Check that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly. P.1-3
Settings Is the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs be-
fore racing? Are inspection and maintenance completely done?
P.7-1 – 10

3-6
ENGINE
ENGINE
CHECKING THE COOLANT LEVEL
Do not remove the radiator cap
"1", drain bolt and hoses when the
engine and radiator are hot. Scald-
ing hot fluid and steam may be
blown out under pressure, which
could cause serious injury. When
the engine has cooled, place a
thick towel over the radiator cap,
slowly rotate the cap counter-
clockwise to the detent. This pro-
cedure allows any residual
pressure to escape. When the
hissing sound has stopped, press
down on the cap while turning
counterclockwise and remove it.
Hard water or salt water is harmful
to the engine parts. You may use
distilled water, if you can't get soft
water.
1. Place the machine on a level place, and hold it in an upright po-
sition.
2. Remove: • Radiator cap
3. Check: • Coolant level "a"Coolant level low
→Add coolant.
1. Radiator
CHANGING THE COOLANT
Do not remove the radiator cap
when the engine is hot.
Take care so that coolant does not
splash on painted surfaces. If it
splashes, wash it away with water.
1. Place a container under the en- gine.
2. Remove: • Coolant drain bolt "1"
3. Remove: •Radiator capDrain the coolant completely.
4. Clean:
• Cooling systemThoroughly flush the cooling sys-
tem with clean tap water.
5. Install: • Copper washer
• Coolant drain bolt
6. Fill: •Radiator
•EngineTo specified level.
• Do not mix more than one type of ethylene glycol antifreeze con-
taining corrosion inhibitors for
aluminum engine.
• Do not use water containing im-
purities or oil.
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.
7. Install:•Radiator capStart the engine and warm it up
for a several minutes.
8. 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
Coolant drain bolt: 10 Nm (1.0 m•kg, 7.2
ft•lb)
Recommended coolant: High quality ethylene
glycol anti-freeze con-
taining anti-corrosion
for aluminum engine
Coolant "1" and water
(soft water) "2" mixing ra-
tio: 50%/50%
Coolant capacity:
0.99 L (0.87 Imp qt, 1.05
US qt)
Radiator cap tester:YU-24460-01/90890-
01325
Radiator cap tester
adapter: YU-33984/90890-01352

3-7
ENGINE
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.
ΠDo not apply pressure more than
specified pressure.
• Radiator should be filled fully.
4. Inspect: •Pressure
Impossible 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. Turn the adjuster "2" until free play "a" is within the specified lim-
its.
c. Tighten the locknuts.
ΠBefore adjustment, expose the ad-
juster by moving the boot "3" and
cap "4" away.
• Make minute adjustment on the le- ver side using the adjuster "5".
• After adjustment, check proper op-
eration of clutch lever.
3. Install:•Cap "1"
•Boot "2"
Place the tip "a" of the cap in the boot.
ADJUSTING THE THROTTLE
CABLE FREE PLAY
1. Check:• Throttle grip free play "a"
Out of specification
→Adjust.
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"
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: 4 Nm (0.4 m•kg, 2.9
ft•lb)Throttle grip free play
"a":3–5 mm (0.12–0.20 in)
Locknut: 4 Nm (0.4 m•kg, 2.9
ft•lb)

4-6
RADIATOR
HANDLING NOTE
Do not remove the radiator cap
when the engine and radiator are
hot. Scalding hot fluid and steam
may be blown out under pressure,
which could cause serious injury.
When the engine has cooled, open
the radiator cap by the following
procedure:
Place a thick rag, like a towel, over
the radiator cap, slowly rotate the
cap counterclockwise to the de-
tent. This procedure allows any re-
sidual pressure to escape. When
the hissing sound has stopped,
press down on the cap while turn-
ing counterclockwise and remove
it.
CHECKING THE RADIATOR
1. Inspect:• Radiator core "1"Obstruction
→Blow out with com-
pressed air through rear of the ra-
diator.
Bent fin
→Repair/replace.
INSTALLING THE RADIATOR
1. Install: • O-ring "1"
• Radiator pipe 1 "2"
• Bolt (radiator pipe) "3"
Apply the lithium soap base grease
on the O-ring.
2. Install:• Radiator breather hose "1"
• Radiator hose 2 "2"
• Radiator hose 3 "3"
• Radiator hose 4 "4"
To right radiator "5". 3. Install:
• Right radiator "1"
• Bolt (right radiator) "2"
• Radiator hose 3 "3"Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
4. Install: • Left radiator "1"
• Bolt (left radiator) "2"
• Radiator hose 1 "3"
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
5. Tighten: • Radiator hose clamp "4"
6. Install: • Radiator guard "1"
First fit the inner hook portion "a" and
then the outer one "b" onto the radia-
tor.
Bolt (radiator pipe): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (right radiator):10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (left radiator): 10 Nm (1.0 m•kg, 7.2
ft•lb)
Radiator hose 1: 2 Nm (0.2 m•kg, 1.4
ft•lb)
Radiator hose clamp: 2 Nm (0.2 m•kg, 1.4
ft•lb)