2008 YAMAHA YZ250F air filter

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

1-8
CONTROL FUNCTIONS
CONTROL FUNCTIONS
ENGINE STOP SWITCH
The engine stop switch "1" is located
on the left handlebar. Continue push-
ing the engine stop switch till the en-
gine comes to a stop.
CLUTCH LEVER
The clutch lever "1" is located on the
left handlebar; it disengages or en-
gages the clutch. Pull the clutch lever
to the handlebar to disengage the
clutch, and release the lever to en-
gage the clutch. The lever should be
pulled rapidly and released slowly for
smooth starts.
SHIFT PEDAL
The gear ratios of the constant-mesh
5 speed transmission are ideally
spaced. The gears can be shifted by
using the shift pedal "1" on the left
side of the engine.
KICKSTARTER CRANK
Rotate the kickstarter crank "1" away
from the engine. Push the starter
down lightly with your foot until the
gears engage, then kick smoothly
and forcefully to start the engine. This
model has a primary kickstarter crank
so the engine can be started in any
gear if the clutch is disengaged. In
normal practices, however, shift to
neutral before starting.THROTTLE GRIP
The throttle grip "1" is located on the
right handlebar; it accelerates or de-
celerates the engine. For accelera-
tion, turn the grip toward you; for
deceleration, turn it away from you.
FRONT BRAKE LEVER
The front brake lever "1" is located on
the right handlebar. Pull it toward the
handlebar to activate the front brake.
REAR BRAKE PEDAL
The rear brake pedal "1" is located on
the right side of the machine. Press
down on the brake pedal to activate
the rear brake.
FUEL COCK
The fuel cock supplies fuel from the
tank to carburetor and also filters the
fuel. The fuel cock has the two posi-
tions:
OFF:
With the lever in this position, fuel will
not flow. Always return the lever to
this position when the engine is not
running.
ON:
With the lever in this position, fuel
flows to the carburetor. Normal riding
is done with the lever in this position.COLD STARTER KNOB
When cold, the engine requires a
richer air-fuel mixture for starting. A
separate starter circuit, which is con-
trolled by the cold starter knob "1",
supplies this mixture. Pull the cold
starter knob out to open the circuit for
starting. When the engine has
warmed up, push it in to close the cir-
cuit.
HOT STARTER LEVER
The hot starter lever "1" is used when
starting a warm engine. Use the hot
starter lever when starting the engine
again immediately after it was
stopped (the engine is still warm).
Pulling the hot starter lever injects
secondary air to thin the air-fuel mix-
ture temporarily, allowing the engine
to be started more easily.
STARTING AND BREAK-IN
FUEL
Always use the recommended fuel as
stated below. Also, be sure to use
new gasoline the day of a race.
Use only unleaded gasoline. The
use of leaded gasoline will cause
severe damage to the engine inter-
nal parts such as valves, piston
rings, and exhaust system, etc.
Recommended fuel:
Premium unleaded
gasoline only with a re-
search octane number
of 95 or higher.

2-1
GENERAL SPECIFICATIONS
SPECIFICATIONS
GENERAL SPECIFICATIONS
Model name:YZ250FX (USA, CDN, AUS, NZ)
YZ250F (EUROPE, ZA)
Model code number: 5XCL (USA,CDN)
5XCM (EUROPE)
5XCP (AUS, NZ, ZA)
Dimensions: USA, CDN, ZA, AUS, NZEUROPE
Overall length 2,162 mm (85.12 in) 2,165 mm (85.24 in)
Overall width 825 mm (32.48 in)
←
Overall height1,300 mm (51.18 in)←
Seat height 985 mm (38.78 in)997 mm (39.25 in)
Wheelbase 1,469 mm (57.83 in)
←
Minimum ground clearance370 mm (14.57 in)372 mm (14.65 in)
Dry weight: Without oil and fuel 92.7 kg (204 lb)
Engine: Engine type Liquid cooled 4-stroke, DOHC
Cylinder arrangement Single cylinder, forward inclined
Displacement 249 cm
3 (8.76 Imp oz, 8.42 US oz)
Bore × stroke 77.0 × 53.6 mm (3.03 × 2.11 in)
Compression ratio 13.5 : 1
Starting system Kickstarter
Lubrication system: Dry sump
Oil type or grade: Engine oil (For USA and CDN)
Yamalube 4, SAE10W30 or SAE20W40
Yamalube 4-R, SAE10W50
API service SG type or higher,
JASO standard MA
(Except for USA and CDN)
SAE10W30, SAE10W40, SAE15W40,
SAE20W40 or SAE20W50
API service SG type or higher,
JASO standard MA
Oil capacity: Engine oilPeriodic oil change 1.05 L (0.92 Imp qt, 1.11 US qt)
With oil filter replacement 1.15 L (1.01 Imp qt, 1.22 US qt)
Total amount 1.30 L (1.14 Imp qt, 1.37 US qt)
Coolant capacity (including all routes): 0.99 L (0.87 Imp qt, 1.05 US qt)
Air filter: Wet type element
2

2-7
MAINTENANCE SPECIFICATIONS
Quantity8----
Warp limit ----0.1 mm (0.004
in)
Clutch spring free length 35.7 mm (1.41 in)34.7 mm (1.37
in)
Quantity 5----
Clutch housing thrust clearance 0.10–0.35 mm (0.0039–0.0138 in) ----
Clutch housing radial clearance 0.010–0.044 mm (0.0004–0.0017 in) ----
Clutch release method Inner push, cam push----
Shifter: Shifter type Cam drum and guide bar----
Guide bar bending limit ----0.05 mm (0.002
in)
Kickstarter: Type Kick and ratchet type----
Carburetor: Type/manufacturer FCR-MX37/KEIHIN----
I. D. mark 5XCL L0----
Main jet (M.J) #178----
Main air jet (M.A.J) ø2.0----
Jet needle-clip position (J.N) NFPR-5----
Cutaway (C.A) 1.5----
Pilot jet (P.J) #42----
Pilot air jet (P.A.J) #105----
Pilot outlet (P.O) ø0.9----
Pilot screw (example) (P.S) 2-3/8----
Bypass (B.P) ø1.0----
Valve seat size (V.S) ø3.8----
Starter jet (G.S) #72----
Leak jet (Acc.P) #70----
Float height (F.H) 8 mm (0.31 in)----
Engine idle speed 1,900–2,100 r/min----
Intake vacuum 29.3–34.7 kPa (220–260 mmHg, 8.66–
9.45 inHg) ----
Hot starter lever free play 3–6 mm (0.12–0.24 in)----
Lubrication system: Oil filter type Paper type----
Oil pump type Trochoid type----
Tip clearance 0.12 mm or less (0.0047 in or less) 0.20 mm (0.008
in)
Side clearance 0.09–0.17 mm (0.0035–0.0067 in) 0.24 mm (0.009
in)
Housing and rotor clearance 0.03–0.10 mm (0.0012–0.0039 in) 0.17 mm
(0.0067 in)
Cooling: Radiator core sizeWidth 120.2 mm (4.7 in)----
Item
StandardLimit

2-11
TIGHTENING TORQUES
Oil tank drain boltM8 × 1.25 1 18 1.8 13
Oil tank (upper) M6 × 1.0 1 7 0.7 5.1
Oil tank and frame M6 × 1.0 3 9 0.9 6.5
Carburetor joint clamp M4 × 0.7 2 3 0.3 2.2
Air filter joint clamp M6 × 1.0 1 3 0.3 2.2
Throttle cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Throttle cable (pull) M6 × 1.0 1 4 0.4 2.9
Throttle cable (return) M12 × 1.0 1 11 1.1 8.0
Throttle cable cover M5 × 0.8 2 4 0.4 2.9
Hot starter plunger M12 × 1.0 1 2 0.2 1.4
Hot starter cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
△Air filter case M6 × 1.0 2 8 0.8 5.8
Air filter joint and air filter case M5 × 0.8 1 4 0.4 2.9
Air filter element M6 × 1.0 1 2 0.2 1.4
Exhaust pipe M8 × 1.25 2 20 2.0 14
△Exhaust pipe protector M6 × 1.0 3 10 1.0 7.2
△SilencerM8 × 1.25 2 30 3.0 22
Silencer clamp M8 × 1.25 1 16 1.6 11
Crankcase M6 × 1.0 11 12 1.2 8.7
Crankcase bearing stopper M6 × 1.0 11 10 1.0 7.2
Crankcase bearing stopper (crankshaft) M6 × 1.0 4 14 1.4 10
Oil level check window holder M6 × 1.0 1 10 1.0 7.2
Left crankcase cover M6 × 1.0 8 10 1.0 7.2
Right crankcase cover M6 × 1.0 8 10 1.0 7.2
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase oil drain bolt M10 × 1.25 1 20 2.0 14
△Crankshaft end accessing screw M32 × 1.5 1 — — —
△Timing mark accessing screwM14 × 1.5 1 — — —
Drive chain sprocket cover M6 × 1.0 2 8 0.8 5.8
Kick shaft ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Kickstarter crank M8 × 1.25 1 33 3.3 24
Primary drive gear M18 × 1.0 1 75 7.5 54
Clutch spring M6 × 1.0 5 10 1.0 7.2
Clutch boss M16 × 1.0 1 60 6.0 43
Clutch cable locknut M8 × 1.25 1 7 0.7 5.1
Clutch cable adjust bolt and locknut M6 × 0.75 1 4 0.4 2.9
Push lever shaft M6 × 1.0 1 10 1.0 7.2
Drive sprocket M18 × 1.0 1 75 7.5 54
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Shift pedal M6 × 1.0 1 12 1.2 8.7
Part to be tightened
Thread size Q'tyTightening torque
Nm m•kg ft•lb

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

3-8
ENGINE
2. Apply:• Lithium soap base greaseOn 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. Remove: •Seat
• Fitting bolt "1"
•Washer "2"
• Air filter element "3"
• Air filter guide "4"
2. Clean: • Air filter elementClean them with solvent.
After cleaning, remove 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.
3. Inspect:• Air filter element
Damage
→Replace.
4. Apply: • Foam-air-filter oil or equivalent oil
to the element
Squeeze out the excess oil. Element
should be wet but not dripping.
5. Install:• Air filter guide "1"
Align the projection "a" on filter guide
with the hole "b" in air filter element.
6. Apply:• Lithium soap base grease On the matching surface "a" on air
filter element.
7. Install: • Air filter element "1"
• Washer
• Fitting bolt
Align the projection "a" on filter guide
with the hole "b" in air filter case.
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.
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)
Fitting bolt:
2 Nm (0.2 m•kg, 1.4
ft•lb)

4-2
SEAT, FUEL TANK AND SIDE COVERS
REMOVING THE SIDE COVER
1. Remove:• Bolt (side cover)
• Left side cover "1"
• Right side cover "2"
Draw the side cover downward to re-
move it because its claws "a" are in-
serted in the air filter case.
REMOVING THE NUMBER PLATE
1. Remove:• Bolt (number plate)
• Number plate "1"
• The projection "a" is inserted into
the band of the number plate. Pull
the band off the projection before
removal.
• Remove the hot starter cable "2" and clutch cable "3" from the cable
guide "b" on the number plate.
• The projection "c" on the lower bracket is inserted into the number
plate. Remove the number plate by
pulling it off the projection.
INSTALLING THE AIR SCOOP
1. Install• Air scoop "1"
• Bolt (air scoop)
Put the portion "a" of the flap of the air
filter case on the inside of the air
scoop.
Bolt (air scoop):
7 Nm (0.7 m•kg, 5.1
ft•lb)
4