valve YAMAHA YZ250F 2005 User Guide

SPEC
2 - 14
NOTE:
1. First, tighten the steering nut approximately 38 Nm (3.8 m  kg, 27 ft  lb) by using the steering nut
wrench, then loosen the steering nut one turn.
2. Retighten the steering nut 7 Nm (0.7 m  kg, 5.1 ft  lb). Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Upper bracket and outer tube M8 × 1.25 4 23 2.3 17
Lower bracket and outer tube M8 × 1.25 4 20 2.0 14
Upper bracket and steering stem M24 × 1.0 1 145 14.5 105
Handlebar holder and upper bracket M8 × 1.25 4 28 2.8 20
Steering stem and steering ring nut M28 × 1.0 1 Refer to NOTE.
Front fork and damper assembly M51 × 1.5 2 30 3.0 22
Front fork and adjuster M22 × 1.25 2 55 5.5 40
Damper assembly and base valve M42 × 1.5 2 29 2.9 21
Adjuster and damper assembly M12 × 1.25 2 29 2.9 21
Front fork bleed screw and base valve M5 × 0.8 2 1 0.1 0.7
Front fork and front fork protector M6 × 1.0 6 10 1.0 7.2
Lower bracket and brake hose guide M6 × 1.0 1 4 0.4 2.9
Front fork protector and brake hose holder M6 × 1.0 2 7 0.7 5.1
Throttle grip cap M5 × 0.8 2 4 0.4 2.9
Front brake master cylinder M6 × 1.0 2 9 0.9 6.5
Brake lever mounting bolt M6 × 1.0 1 6 0.6 4.3
Brake lever mounting nut M6 × 1.0 1 6 0.6 4.3
Brake lever position locknut M6 × 1.0 1 5 0.5 3.6
Clutch lever holder M5 × 0.8 2 4 0.4 2.9
Clutch lever mounting nut M6 × 1.0 1 4 0.4 2.9
Hot starter lever holder M5 × 0.8 2 4 0.4 2.9
Front brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Front brake hose union bolt M10 × 1.25 2 30 3.0 22
Front brake caliper M8 × 1.25 2 23 2.3 17
Front brake caliper and brake hose holder M6 × 1.0 1 10 1.0 7.2
Pad pin plug M10 × 1.0 2 3 0.3 2.2
Front brake caliper and pad pin M10 × 1.0 1 18 1.8 13
Rear brake caliper and pad pin M10 × 1.0 1 18 1.8 13
Brake caliper and bleed screw M8 × 1.25 2 6 0.6 4.3
Front wheel axle and axle nut M16 × 1.5 1 105 10.5 75
Front wheel axle holder M8 × 1.25 4 23 2.3 17
Front brake disc M6 × 1.0 6 12 1.2 8.7
Rear brake disc M6 × 1.0 6 14 1.4 10
Brake pedal M8 × 1.25 1 26 2.6 19
Rear brake master cylinder M6 × 1.0 2 11 1.1 8.0
Rear brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Rear brake hose union bolt M10 × 1.25 2 30 3.0 22
Rear wheel axle and axle nut M20 × 1.5 1 125 12.5 90
MAINTENANCE SPECIFICATIONS

SPEC
2 - 14
N.B.:
1. Serrer d’abord l’écrou crénelé à 38 Nm (3,8 m  kg, 27 ft  lb) à l’aide d’une clé à ergots, puis le desserrer
d’un tour.
2. Resserrer l’écrou de direction à 7 Nm (0,7 m  kg, 5,1 ft  lb). Pièce à serrerDiamètre du
filetQtéCouple de serrage
Nm m·kg ft·lb
Té supérieur et fourreau M8 × 1,25 4 23 2,3 17
Té inférieur et fourreau M8 × 1,25 4 20 2,0 14
Té supérieur et arbre de direction M24 × 1,0 1 145 14,5 105
Support de guidon et té supérieur M8 × 1,25 4 28 2,8 20
Colonne de direction et écrou de direction M28 × 1,0 1 Voir N.B.
Fourche et amortisseur complet M51 × 1,5 2 30 3,0 22
Fourche et dispositif de réglage adjuster M22 × 1,25 2 55 5,5 40
Amortisseur complet et soupape de base M42 × 1,5 2 29 2,9 21
Dispositif de réglage et amortisseur complet M12 × 1,25 2 29 2,9 21
Vis de purge de la fourche et valve de réglage M5 × 0,8 2 1 0,1 0,7
Fourche et protection de fourche M6 × 1,0 6 10 1,0 7,2
Té inférieur et guide de durit de frein M6 × 1,0 1 4 0,4 2,9
Protection de fourche et support de durit de frein M6 × 1,0 2 7 0,7 5,1
Capuchon de la poignée des gaz M5 × 0,8 2 4 0,4 2,9
Maître-cylindre de frein avant M6 × 1,0 2 9 0,9 6,5
Boulon de montage du levier de frein M6 × 1,0 1 6 0,6 4,3
Ecrou de montage du levier de frein M6 × 1,0 1 6 0,6 4,3
Contre-écrou de réglage de position du levier de frein M6 × 1,0 1 5 0,5 3,6
Support de levier d’embrayage M5 × 0,8 2 4 0,4 2,9
Ecrou de montage du levier d’embrayage M6 × 1,0 1 4 0,4 2,9
Support du levier de démarrage à chaud M5 × 0,8 2 4 0,4 2,9
Couvercle de maître-cylindre de frein avant M4 × 0,7 2 2 0,2 1,4
Boulon de raccord de durit de frein avant M10 × 1,25 2 30 3,0 22
Etrier de frein avant M8 × 1,25 2 23 2,3 17
Etrier de frein avant et support de durit de frein M6 × 1,0 1 10 1,0 7,2
Bouchon de goupille de plaquette M10 × 1,0 2 3 0,3 2,2
Etrier de frein avant et goupille de plaquette M10 × 1,0 1 18 1,8 13
Etrier de frein arrière et goupille de plaquette M10 × 1,0 1 18 1,8 13
Etrier de frein et vis de purge M8 × 1,25 2 6 0,6 4,3
Axe de roue avant et écrou d’axe M16 × 1,5 1 105 10,5 75
Support d’axe de roue avant M8 × 1,25 4 23 2,3 17
Disque de frein avant M6 × 1,0 6 12 1,2 8,7
Disque de frein arrière M6 × 1,0 6 14 1,4 10
Pédale de frein M8 × 1,25 1 26 2,6 19
Maître-cylindre de frein arrière M6 × 1,0 2 11 1,1 8,0
Couvercle de maître-cylindre de frein arrière M4 × 0,7 2 2 0,2 1,4
Boulon de raccord de durit de frein arrière M10 × 1,25 2 30 3,0 22
Axe de roue arrière et écrou d’axe M20 × 1,5 1 125 12,5 90
CARACTERISTIQUES D’ENTRETIEN

3 - 1
INSP
ADJ
MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind
that such factors as weather, terrain, geographical location, and individual usage will alter the
required maintenance and lubrication intervals. If you are a doubt as to what intervals to follow in
maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every
third
(or
500 km)Every
fifth
(or
1,000 km)As re-
quiredRemarks
ENGINE OIL
Replace
Inspect
OIL FILTER ELEMENT, OIL STRAINER
Clean
VALVES
The engine must be cold.
Check the valve seats
and valve stems for wear. Check the valve clearances
Inspect
Replace
VALVE SPRINGS
Check the free length and
the tilt. Inspect
Replace
VALVE LIFTERS
Check for scratches and
wear. Inspect
Replace
CAMSHAFTS Inspect the camshaft sur-
face.
Inspect the decompres-
sion system. Inspect
Replace
TIMING CHAIN SPROCKETS, TIMING
CHAIN
Check for wear on the
teeth and for damage. Inspect
Replace
PISTON
Inspect
Inspect crack
Inspect carbon deposits
and eliminate them. Clean
Replace
PISTON RING
InspectCheck ring end gap
Replace
PISTON PIN
Inspect
Replace
CYLINDER HEAD Inspect carbon deposits
and eliminate them.
Change gasket Inspect and clean
CYLINDER
Inspect and clean
Inspect score marks
Inspect wear
Replace
CLUTCH
Inspect housing, friction
plate, clutch plate and
spring Inspect and adjust
Replace
TRANSMISSION
Inspect
Replace bearing

3 - 7
INSP
ADJ
RADIATOR CAP INSPECTION
CAUTION:
Do not mix more than one type of ethyl-
ene glycol antifreeze containing corro-
sion inhibitors for aluminum engine.
Do not use water containing impurities or
oil.
7. Install:
Radiator cap
Start the engine and warm it up for a sev-
eral minutes.
8. Check:
Coolant level
Coolant level low → Add coolant. Handling notes of coolant:
The coolant is harmful so it should be han-
dled with special care.
WARNING
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.
EC355000
RADIATOR CAP INSPECTION
1. Inspect:
Seal (radiator cap) 1
Valve and valve seat 2
Crack/damage → Replace.
Exist fur deposits 3 → Clean or replace.

3 - 18
INSP
ADJ
ENGINE IDLING SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it up.
2. Adjust:
Engine idling speed
Adjustment steps:
Adjust the pilot screw.
Refer to “PILOT SCREW ADJUSTMENT”
section.
Turn the throttle stop screw 1 until the
specified engine idling speed.
NOTE:
Using a digital engine tachometer for idle
speed adjustment, detect the engine idling
speed by bringing the sensing element c of
the engine tachometer close to the ignition
coil 2.
To increase idle speed → Turn the throt-
tle stop screw 1 in a.
To decrease idle speed → Turn the throt-
tle stop screw 1 out b.
Engine idling speed:
1,900 ~ 2,100 r/min
c2
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
NOTE:
The valve clearance should be adjusted
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 tank
Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
2. Drain:
Coolant
Refer to “COOLANT REPLACEMENT”
section.
ENGINE IDLING SPEED ADJUSTMENT/
VALVE CLEARANCE INSPECTION AND ADJUSTMENT

3 - 19
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
3. Remove:
Right radiator
Refer to “RADIATOR” section in the
CHAPTER 4.
Carburetor
Refer to “CARBURETOR” section in the
CHAPTER 4.
Spark plug
Upper engine bracket
Cylinder head cover
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
4. Remove:
Timing mark accessing screw 1
Crankshaft end accessing screw 2
O-ring
5. Check:
Valve clearance
Out of specification → Adjust.
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 - 20
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
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.
NOTE:
In order to be sure that the piston is at Top
Dead Center, the punch mark c on the
exhaust camshaft and the punch mark d on
the intake camshaft must align with the cyl-
inder head surface, as shown in the illustra-
tion.
Measure the valve clearance e using a
feeler gauge 1.
NOTE:
Record the measured reading if the clear-
ance is incorrect.
6. Adjust:
Valve clearance
Adjustment steps:
Remove the camshaft (intake and
exhaust).
Refer to “CAMSHAFTS” section in the
CHAPTER 4.

3 - 21
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Remove the valve lifters 1 and the pads
2.
NOTE:
Place a rag in the timing chain space to
prevent pads from falling into the crank-
case.
Identity each valve lifter and pad position
very carefully so that they can be rein-
stalled in their original place.
Select the proper pad using the pad
selecting table.
Pad rangePad Availability:
25 increments
No. 120
~
No. 2401.20 mm
~
2.40 mmPads are available in
0.05 mm increments
NOTE:
The thickness a of each pad is indicated in
hundreths of millimeters on the pad upper
surface.
Round off the last digit of the installed pad
number to the nearest increment.
Last digit of pad
numberRounded value
0, 1 or 2 0
4, 5 or 6 5
8 or 9 10
EXAMPLE:
Installed pad number = 148
Rounded off value = 150
NOTE:
Pads can only be selected in 0.05 mm incre-
ments.
Locate the rounded-off value and the mea-
sured valve clearance in the chart “PAD
SELECTION TABLE”. The field where
these two coordinates intersect shows the
new pad number to use.
NOTE:
Use the new pad number only as a guide
when verifying the valve clearance adjust-
ment.

3 - 22
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Install the new pads 3 and the valve lift-
ers 4.
NOTE:
Apply the engine oil on the valve lifters.
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.
Install the camshafts (exhaust and intake).
Refer to “CAMSHAFTS” section in the
CHAPTER 4.

3 - 23
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
INTAKE
MEASURED
CLEARANCEINSTALLED PAD NUMBER
120 125 130 135 140 145 150 155 160 165 170
175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.00 ~ 0.04 120 125 130 135 140 145 150 155
160165 170 175 180 185 190 195 200 205 210 215 220 225 230
0.05 ~ 0.09
120 125 130 135 140 145 150 155 160 165170 175 180 185 190 195 200 205 210 215 220 225 230 235
0.10 ~ 0.15
STANDARD CLEARANCE
0.16 ~ 0.20125130135140145150155160165170175180 185 190 195 200 205 210 215 220 225 230 235240
0.21 ~ 0.25130135140145150155160165170175180185 190 195 200 205 210 215 220 225 230 235240
0.26 ~ 0.30 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.31 ~ 0.35 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.36 ~ 0.40 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.41 ~ 0.45 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.46 ~ 0.50 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.51 ~ 0.55 160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.56 ~ 0.60 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.61 ~ 0.65 170 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.66 ~ 0.70 175 180 185 190 195 200 205 210 215 220 225 230 235240
0.71 ~ 0.75 180 185 190 195 200 205 210 215 220 225 230 235240
0.76 ~ 0.80 185 190 195 200 205 210 215 220 225 230 235240VALVE CLEARANCE (cold):
0.10 ~ 0.15 mm
Example: Installed is 175
Measured clearance is 0.23 mm
Replace 175 pad with 185 pad
Pad number: (example)
Pad No. 175 = 1.75 mm
Pad No. 185 = 1.85 mm
0.81 ~ 0.85 190 195 200 205 210 215 220 225 230 235240
0.86 ~ 0.90 195 200 205 210 215 220 225 230 235240
0.91 ~ 0.95 200 205 210 215 220 225 230 235240
0.96 ~ 1.00 205 210 215 220 225 230 235240
1.01 ~ 1.05 210 215 220 225 230 235240
1.06 ~ 1.10 215 220 225 230 235240
1.11 ~ 1.15 220 225 230 235240
1.16 ~ 1.20 225 230 235240
1.21 ~ 1.25 230 235240
1.26 ~ 1.30 235240
1.31 ~ 1.35 240
EXHAUST
MEASURED
CLEARANCEINSTALLED PAD NUMBER
120 125 130 135 140 145 150 155 160 165 170
175 180 185 190 195 200 205 210 215 220 225 230 235 240
0.00 ~ 0.04 120 125 130 135 140 145 150 155
160 165 170 175 180 185 190 195 200 205 210 215 220 225
0.05 ~ 0.09
120 125 130 135 140 145 150 155 160165 170 175 180 185 190 195 200 205 210 215 220 225 230
0.10 ~ 0.16
120125130135140145150155160165170 175 180 185 190 195 200 205 210 215 220 225230235
0.17 ~ 0.22STANDARD CLEARANCE
0.23 ~ 0.25 125 130 135 140 145 150 155 160 165 170 175
180 185 190 195 200 205 210 215 220 225230235 240
0.26 ~ 0.30130135140145150155160165170175180185 190 195 200 205 210 215 220 225230235240
0.31 ~ 0.35 135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.36 ~ 0.40 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.41 ~ 0.45 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.46 ~ 0.50 150 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.51 ~ 0.55 155 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.56 ~ 0.60 160 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.61 ~ 0.65 165 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.66 ~ 0.70 170 175 180 185 190 195 200 205 210 215 220 225230235240
0.71 ~ 0.75 175 180 185 190 195 200 205 210 215 220 225230235240
0.76 ~ 0.80 180 185 190 195 200 205 210 215 220 225230235240
0.81 ~ 0.85 185 190 195 200 205 210 215 220 225230235240
0.86 ~ 0.90 190 195 200 205 210 215 220 225230235240VALVE CLEARANCE (cold):
0.17 ~ 0.22 mm
Example: Installed is 175
Measured clearance is 0.27 mm
Replace 175 pad with 185 pad
Pad number: (example)
Pad No. 175 = 1.75 mm
Pad No. 185 = 1.85 mm
0.91 ~ 0.95 195 200 205 210 215 220 225230235240
0.96 ~ 1.00 200 205 210 215 220 225230235240
1.01 ~ 1.05 205 210 215 220 225230235240
1.06 ~ 1.10 210 215 220 225230235240
1.11 ~ 1.15 215 220 225230235240
1.16 ~ 1.20 220 225230235240
1.21 ~ 1.25 225230235240
1.26 ~ 1.30 230235240
1.31 ~ 1.35 235240
1.36 ~ 1.40 240