Yamaha YXR70FX Service Manual page 180

VALVES AND VALVE SPRINGS
2. Replace:
• valve guide
TIP:
_
To ease valve guide removal and installation,
and to maintain the correct fit, heat the cylinder
head to 100 °C (212 °F) in an oven.
M MMM
a. Remove the valve guide using a valve guide
remover 1.
b. Install the new valve guide using a valve
guide remover 1 and valve guide installer
2.
c. After installing the valve guide, bore the
valve guide using a valve guide reamer 3
to obtain proper stem-to-guide clearance.
L LLL
TIP:
_
After replacing the valve guide, reface the
valve seat.
3. Check:
• valve face
Pitting/wear → Grind the face.
• valve stem end
Mushroom shape or diameter larger than
the body of the valve stem → Replace.
4 - 30
ENG
M MMM M M MMM M M MMM M M MMM
Valve guide position a
12.7 ~ 13.1 mm (0.50 ~ 0.52 in)
Valve guide remover (ø6)
90890-04064
Valve guide remover (6.0 mm)
YM-04064-A
Valve guide installer (ø6)
90890-04065
Valve guide installer (6.0 mm)
YM-04065-A
Valve guide reamer (ø6)
90890-04066
Valve guide reamer (6.0 mm)
YM-04066
L LLL L L LLL L L LLL L L LLL
M M MMM M MMM
L L LLL L LLL