Yamaha VMX12 2001 Service Manual page 157

VALVES AND VALVE SPRINGS
2. Replace:
NOTE:
@
To ease valve guide removal and installation,
and to maintain the correct fit, heat the cylinder
head to 100 °C in an oven.
@
a. Remove the valve guide with the valve
b. Install the new valve guide with the valve
c. After installing the valve guide, bore the
NOTE:
@
After replacing the valve guide, reface the
valve seat.
@
3. Eliminate:
4. Check:
5. Measure:
4 - 27
• valve guide
guide remover 1.
guide installer 2 and valve guide remover
1.
valve guide with the valve guide reamer 3
to obtain the proper valve-stem-to-valve-
guide clearance.
Valve guide remover (5.5 mm)
90890-01122
Valve guide installer (5.5 mm)
90890-04015
Valve guide reamer (5.5 mm)
90890-01196
• carbon deposits
(from the valve face and valve seat)
• valve face
Pitting/wear → Grind the valve face.
• valve stem end
Mushroom shape or diameter larger than
the body of the valve stem → Replace the
valve.
• valve margin thickness a
Out of specification → Replace the valve.
Valve margin thickness
1.1 ~ 1.5 mm
<Limit>: 0.7 mm
ENG