Checking The Valves And Valve Guides - Yamaha YZ450FX 2019 Owner's Service Manual

that it can be reinstalled in its original place.
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EAM30091
CHECKING THE VALVES AND VALVE
GUIDES
1. Measure:
• Valve-stem-to-valve-guide clearance
Out of specification  Replace the valve
guide.
Valve-stem-to-valve-guide clearance =
Valve guide inside diameter "a" -
Valve stem diameter "b"
Valve-stem-to-valve-guide clear-
ance (intake)
0.010–0.037 mm (0.0004–0.0015
in)
Limit
0.080 mm (0.0032 in)
Valve-stem-to-valve-guide clear-
ance (exhaust)
0.020–0.047 mm (0.0008–0.0019
in)
Limit
0.100 mm (0.0039 in)
VALVES AND VALVE SPRINGS
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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".
b. Install the new valve guide with the valve
guide installer "1" and the valve guide remov-
er "2".
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Valve guide installation height "a"
Intake
15.1–15.5 mm (0.59–0.61 in)
Exhaust
11.7–12.1 mm (0.46–0.48 in)