Checking The Valve Guide; Replacing The Valve Guide - Yamaha F30B 2018 Service Manual

4. Measure:
• Stem runout
Above specification  Replace.
Runout limit EX
0.01 mm (0.0004 in)
Runout limit IN
0.01 mm (0.0004 in)

Checking the valve guide

Before checking the valve guides, make sure
that the valve stem diameter is within specifica-
tion.
1. Measure:
• Inside diameter "a"
Above specification  Replace.
a
Inside diameter IN
5.500–5.512
0.2170 in)
Inside diameter EX
5.500–5.512
0.2170 in)
mm (0.2165–
mm (0.2165–
7-34
2. Calculate:
• Valve stem to valve guide clearance
Out of specification  Replace the valve
and valve guide.
Valve stem to valve guide clear-
ance = valve guide inside diameter
– valve stem diameter
Clearance IN
0.010–0.037
0.0015 in)
Limit
0.070 mm (0.0028 in)
Clearance EX
0.025–0.052
0.0020 in)
Limit
0.070 mm (0.0028 in)

Replacing the valve guide

After replacing a valve guide, check the valve
seat contact area.
1. Remove:
• Valve guide "1" (from the combustion
chamber side)
Valve guide remover/installer "2"
90890-06801
Valve guide remover "2"
YB-06801
Camshaft and valve
mm (0.0004–
mm (0.0010–
2
1