Checking The Valves And Valve Guides - Yamaha WR450FB 2012 Owner's Service Manual

EAS24290 ·
CHECKING THE VALVES AND VALVE
GUIDES
The following procedure applies to all of 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)
2. Replace:
• Valve guide
VALVES AND VALVE SPRINGS
·TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
a. Remove the valve guide with the valve guide
remover "1 ".
b. Install the new valve guide with the valve
guide installer "2" and valve guide remover
"1n.
Valve guide installation height "a"
Intake
10.3-10.7
mm
(0.41-0.42
in)
Exhaust
10.3-10.7 mm (0.41-0.42 in)
2
0
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 _ _ _ _ _ _ _ _ _ _ _ _ _ _
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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