4-23
VALVES AND VALVE SPRINGS
4. Measure:
• Margin thickness "a"
Out of specification
→
Replace.
5. Measure:
• Runout (valve stem)
Out of specification
→
Replace.
• When installing a new valve always
replace the guide.
• If the valve is removed or replaced
always replace the oil seal.
6. Eliminate:
• Carbon deposits
(from the valve face and valve
seat)
7. Inspect:
• Valve seat
Pitting/wear
→
Reface the valve
seat.
8. Measure:
• Valve seat width "a"
Out of specification
→
Reface the
valve seat.
Measurement steps:
a. Apply Mechanic's blueing dye
(Dykem) "b" to the valve face.
b. Install the valve into the cylinder
head.
c. Press the valve through the valve
guide and onto the valve seat to
make a clear pattern.
d. Measure the valve seat width.
Where the valve seat and valve
face made contact, blueing will
have been removed.
e. If the valve seat is too wide, too
narrow, or the seat is not cen-
tered, the valve seat must be re-
faced.
9. Lap:
• Valve face
• Valve seat
After refacing the valve seat or re-
placing the valve and valve guide, the
valve seat and valve face should be
lapped.
Lapping steps:
a. Apply a coarse lapping compound
to the valve face.
Do not let the compound enter the
gap between the valve stem and
the guide.
b. Apply molybdenum disulfide oil to
the valve stem.
c. Install the valve into the cylinder
head.
d. Turn the valve until the valve face
and valve seat are evenly pol-
ished, then clean off all of the
compound.
For best lapping results, lightly tap
the valve seat while rotating the valve
back and forth between your hands.
e. Apply a fine lapping compound to
the valve face and repeat the
above steps.
After every lapping operation be sure
to clean off all of the compound from
the valve face and valve seat.
f. Apply Mechanic's blueing dye
(Dykem) to the valve face.
g. Install the valve into the cylinder
head.
h. Press the valve through the valve
guide and onto the valve seat to
make a clear pattern.
i. Measure the valve seat width
again. If the valve seat width is out
of specification, reface and relap
the valve seat.
CHECKING THE VALVE SPRINGS
1. Measure:
• Valve spring free length "a"
Out of specification
→
Replace.
Margin thickness:
Intake:
0.8 mm (0.0315 in)
Exhaust:
0.7 mm (0.0276 in)
Runout limit:
0.01 mm (0.0004 in)
Valve seat width:
Intake:
0.9–1.1 mm (0.0354–
0.0433 in)
<Limit>:1.6 mm
(0.0630 in)
Exhaust:
0.9–1.1 mm (0.0354–
0.0433 in)
<Limit>:1.6 mm
(0.0630 in)
Free length (valve
spring):
Intake:
37.81 mm (1.49 in)
<Limit>: 36.81 mm
(1.45 in)
Exhaust:
37.54 mm (1.48 in)
<Limit>: 36.54 mm
(1.44 in)
Содержание YZ250F(X)
Страница 2: ......
Страница 37: ...2 17 LUBRICATION DIAGRAMS 1 Crankshaft 2 Oil filter element 3 Oil tank 4 Oil hose A From oil pump ...
Страница 57: ...3 13 ENGINE INTAKE EXHAUST ...
Страница 108: ...4 41 OIL PUMP 15 Rotor housing 1 Order Part name Q ty Remarks ...
Страница 159: ...5 29 STEERING 9 Bearing race 2 Refer to removal section Order Part name Q ty Remarks ...
Страница 168: ...5 38 REAR SHOCK ABSORBER 12 Bearing 2 Refer to removal section Order Part name Q ty Remarks ...
Страница 243: ...3 13 MOTEUR ADMISSION ECHAPPEMENT ...
Страница 275: ...4 21 CULASSE 7 Carter de chaîne de distribution côté échappe ment 1 Ordre Nom de la pièce Qté Remarques ...
Страница 298: ...4 44 BALANCIER 5 Replier l onglet de la rondelle frein ...
Страница 300: ...4 46 POMPE A HUILE 14 Arbre d entraînement de pompe à huile 1 15 Boîtier du rotor 1 Ordre Nom de la pièce Qté Remarques ...
Страница 361: ...5 38 AMORTISSEUR ARRIERE 12 Roulement 2 Se reporter à la section de dépose Ordre Nom de la pièce Qté Remarques ...
Страница 384: ......
Страница 419: ...2 17 SCHMIERSYSTEM SCHAUBILDER 1 Kurbelwelle 2 Ölfiltereinsatz 3 Öltank 4 Ölschlauch A Von der Ölpumpe ...
Страница 439: ...3 13 MOTOR EINLASS AUSLASS ...
Страница 495: ...4 45 ÖLPUMPE 15 Rotorgehäuse 1 Reihenfolge Bauteil Anz Bemerkungen ...
Страница 555: ...5 38 FEDERBEIN 12 Lager 2 Siehe den Abschnitt zum Ausbau Reihenfolge Bauteil Anz Bemerkungen ...
Страница 578: ......
Страница 634: ...3 14 MOTORE ASPIRAZIONE SCARICO ...
Страница 685: ...4 40 ELEMENTO FILTRO OLIO E POMPA DELL ACQUA Applicare il grasso a base di sapone di litio sulla guarnizione circolare ...
Страница 688: ...4 43 EQUILIBRATORE 5 Piegare la linguetta della rondella di bloccaggio ...
Страница 690: ...4 45 POMPA DELL OLIO 15 Alloggiamento del rotore 1 Ordine Denominazione Quantità Osservazioni ...
Страница 774: ......
Страница 775: ......