2007 YAMAHA YZ250F valve

3 - 20
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
Measure the valve clearance e using a
feeler gauge 1.
NOTE:
Record the measured reading if the clear-
ance is incorrect.
5. Adjust:
Valve clearance
Adjustment steps:
Remove the camshaft (intake and
exhaust).
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
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

3 - 21
INSP
ADJ
VALVE CLEARANCE INSPECTION AND ADJUSTMENT
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.
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 - 22
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

3 - 40
INSP
ADJTIRE PRESSURE CHECK/SPOKES INSPECTION AND
TIGHTENING/WHEEL INSPECTION
EC36Q000
TIRE PRESSURE CHECK
1. Measure:
Tire pressure
Out of specification → Adjust.
NOTE:
Check the tire while it is cold.
Loose bead stoppers allow the tire to slip off
its position on the rim when the tire pressure
is low.
A tilted tire valve stem indicates that the tire
slips off its position on the rim.
If the tire valve stem is found tilted, the tire is
considered to be slipping off its position. Cor-
rect the tire position.
Standard tire pressure:
100 kPa (1.0 kgf/cm2, 15 psi)
EC36S002
SPOKES INSPECTION AND TIGHTENING
1. Inspect:
Spokes 1
Bend/damage → Replace.
Loose spoke → Retighten.
2. Tighten:
Spokes
NOTE:
Be sure to retighten these spokes before and
after break-in. After a practice or a race check
spokes for looseness.
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)
EC36T000
WHEEL INSPECTION
1. Inspect:
Wheel runout
Elevate the wheel and turn it.
Abnormal runout → Replace.

INSP
ADJ
REIFENLUFTDRUCK
KONTROLLIEREN
1. Messen:
Reifenluftdruck
Nicht nach Vorgabe → Einstel-
len.
HINWEIS:
Den Reifenluftdruck bei kaltem
Reifen kontrollieren.
Bei zu niedrigem Reifenluftdruck
besteht die Gefahr, dass der Rei-
fen auf der Felge rutscht.
Ein schräg stehender Ventilschaft
deutet darauf hin, dass der Reifen
sich verschoben hat.
Falls der Ventilschaft schräg steht,
sitzt der Reifen falsch auf. In die-
sem Fall die Reifenlage korrigieren.
Standard-Reifenluft-
druck:
100 kPa
(1,0 kgf/cm
2, 15 psi)
SPEICHEN KONTROLLIEREN UND
SPANNEN
1. Kontrollieren:
Speichen 1
Verbogen/beschädigt →
Erneuern.
Speiche lose → Spannen.
2. Festziehen:
Speichen
HINWEIS:
Die Speichen müssen vor und nach
dem Einfahren gespannt und nach
jeder Fahrt kontrolliert werden.
T R..3 Nm (0,3 m · kg, 2,2 ft · lb)
RÄDER KONTROLLIEREN
1. Kontrollieren:
Felgenschlag
Das Rad anheben und dre-
hen.
Anormaler Schlag → Erneu-
ern. CONTROLE DE LA PRESSION DES
PNEUS
1. Mesurer:
Pression des pneus
Hors spécifications → Régler.
N.B.:
Contrôler les pneus à froid.
Le pneu risque de se déjanter si le
gonflage est insuffisant.
Une tige de valve de pneu inclinée
indique que le pneu est mal assis.
Une tige de valve de pneu inclinée
indique que le pneu est mal assis. Cor-
riger la position du pneu.
Pression des pneus stan-
dard:
100 kPa
(1,0 kgf/cm
2, 15 psi)
CONTROLE ET SERRAGE DES
RAYONS
1. Contrôler:
Rayons 1
Déformation/endommagement →
Remplacer.
Rayon desserré → Resserrer.
2. Serrer:
Rayons
N.B.:
Veiller à resserrer ces rayons avant et
après le rodage. Après tout entraînement
ou toute course, contrôler la tension des
rayons.
T R..3 Nm (0,3 m · kg, 2,2 ft · lb)
CONTROLE DES ROUES
1. Contrôler:
Voile de roue
Surélever la roue et la faire tour-
ner.
Voile excessif → Remplacer.CONTROLLO PRESSIONE DEI
PNEUMATICI
1. Misurare:
Pressione dei pneumatici
Non conforme alle specifiche →
Regolare.
NOTA:
Controllare il pneumatico quando è
freddo.
Se gli elementi di arresto del tallone
sono lenti, il pneumatico scivola via
dalla sua posizione sul cerchio quando
la pressione è bassa.
La valvola del pneumatico inclinata
indica che il pneumatico scivola via
dalla sua posizione sul cerchio.
Se si nota che la valvola del pneuma-
tico è inclinata, il pneumatico è fuori
posizione. Correggere la posizione del
pneumatico.
Pressione standard dei
pneumatici:
100 kPa
(1,0 kgf/cm
2, 15 psi)
CONTROLLO E SERRAGGIO DEI
RAGGI
1. Controllare:
Raggi 1
Deformazioni/danni → Sostituire.
Raggio lento → Serrare.
2. Serrare:
Raggi
NOTA:
Assicurarsi di serrare i raggi prima e
dopo il rodaggio. Dopo l’utilizzo o dopo
una competizione, controllare che i raggi
non siano lenti.
T R..3 Nm (0,3 m · kg, 2,2 ft · lb)
CONTROLLO DELLE RUOTE
1. Controllare:
Scentratura ruota
Sollevare la ruota e farla ruotare.
Scentratura anomala → Sostitu-
ire.
CONTROLE DE LA PRESSION DES PNEUS/
CONTROLE ET SERRAGE DES RAYONS/CONTROLE DES ROUES
REIFENLUFTDRUCK KONTROLLIEREN/
SPEICHEN KONTROLLIEREN UND SPANNEN/RÄDER KONTROLLIEREN
CONTROLLO PRESSIONE DEI PNEUMATICI/
CONTROLLO E SERRAGGIO DEI RAGGI/CONTROLLO DELLE RUOTE
3 - 40

4 - 10
ENGCARBURETOR
EC468000
CARBURETOR DISASSEMBLY
Extent of removal:
1 Carburetor disassembly
Extent of removal Order Part name Q’ty Remarks
CARBURETOR DISASSEMBLY
1Carburetor breather hose 4
2Valve lever housing cover 1
3Screw (throttle shaft) 1
4Throttle valve 1
5Needle holder 1
6Jet needle 1
7Accelerator pump cover 1
8Spring 1
9Diaphragm (accelerator pump) 1
0Float chamber 1
ALeak jet 1
BPilot screw 1 Refer to “REMOVAL POINTS”.
CFloat pin 1
DFloat 1
ENeedle valve 1
1

4 - 13
ENGCARBURETOR
2. Inspect:
Main jet 1
Pilot jet 2
Needle jet 3
Starter jet 4
Pilot air jet 5
Leak jet 6
Damage → Replace.
Contamination → Clean.
NOTE:
Use a petroleum based solvent for cleaning.
Blow out all passages and jets with com-
pressed air.
Never use a wire.
Needle valve
1. Inspect:
Needle valve 1
Valve seat 2
Grooved wear a → Replace.
Dust b → Clean.
Filter c
Clogged → Clean.
EC464301
Throttle valve
1. Check:
Free movement
Stick → Repair or replace.
NOTE:
Insert the throttle valve 1 into the carburetor
body, and check for free movement.
EC464401
Jet needle
1. Inspect:
Jet needle 1
Bends/wear → Replace.
Clip groove
Free play exists/wear → Replace.
Clip position
Standard clip position:
No.4 Groove

4 - 14
ENGCARBURETOR
Float height
1. Measure:
Float height a
Out of specification → Adjust.
Float height:
8.0 mm (0.31 in)
Measurement and adjustment steps:
Hold the carburetor in an upside down
position.
NOTE:
Slowly tilt the carburetor in the opposite
direction, then take the measurement
when the needle valve aligns with the float
arm.
If the carburetor is level, the weight of the
float will push in the needle valve, resulting
in an incorrect measurement.
Measure the distance between the mating
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
If the float height is not within specification,
inspect the valve seat and needle valve.
If either is worn, replace them both.
If both are fine, adjust the float height by
bending the float tab b on the float.
Recheck the float height.
EC464600
Float
1. Inspect:
Float 1
Damage → Replace.