Yamaha 2009 YFM25RY Service Manual page 183

Valve-stem-to-valve-guide clear-
ance
Valve-stem-to-valve-guide clear-
ance (intake)
0.010–0.037 mm (0.0004–
0.0015 in)
Limit
0.080 mm (0.003 in)
Valve-stem-to-valve-guide clear-
ance (exhaust)
0.025–0.052 mm (0.0010–
0.0020 in)
Limit
0.100 mm (0.004 in)
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.
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a. Remove the valve guide with the valve
guide remover "1".
VALVES AND VALVE SPRINGS
b. Install the new valve guide with the valve
guide installer "2" and valve guide remover
"1".
c. After installing the valve guide, bore the
valve guide with the valve guide reamer "3"
to obtain the proper valve-stem-to-valve-
guide clearance.
TIP
After replacing the valve guide, reface the
valve seat.
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