Valve - Yamaha YZ250F(V) Owner's Service Manual

VALVES AND VALVE SPRINGS
INSPECTION

Valve

1. Measure:
2. Replace:
Replacement steps:
NOTE:
To ease guide removal, installation and to
maintain correct fit heat the cylinder head in
an over to 100 °C (212 °F).
• Remove the valve guide using a valve
• Install the new valve guide using a valve
• After installing the valve guide, bore the
4 - 36
• Stem-to-guide clearance
Stem-to-guide clearance =
valve guide inside diameter a –
valve stem diameter b
Out of specification → Replace the valve
guide.
Clearance (stem to guide):
Intake:
0.010 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
<Limit>: 0.08 mm (0.003 in)
Exhaust:
0.025 ~ 0.052 mm
(0.0010 ~ 0.0020 in)
<Limit>: 0.10 mm (0.004 in)
• Valve guide
guide remover 1.
guide remover 1 and valve guide installer
2.
valve guide using a valve guide reamer 3
to obtain proper stem-to-guide clearance.
ENG