Yamaha F30A, Service Manual

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67C3K11
5-30
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Checking the cylinder head
1. Eliminate carbon deposits from the com-
bustion chambers and check the cylinder
head for damage or scratches.
2. Check the cylinder head warpage using a
straightedge
1
and thickness gauge
2
in the directions shown. Replace the cyl-
inder head assembly if above specifica-
tion.
Checking the valve spring
1. Measure the valve spring free length
a
.
Replace if below specification.
2. Measure the valve spring tilt
b
. Replace
if above specification.
Checking the valve
1. Check the valve face. Replace the valve
if pitted or worn.
2. Measure the valve margin thickness
a
.
Replace the valve if out of specification.
Cylinder head warpage limit:
0.10 mm (0.0039 in)
Valve spring free length
a
:
39.85 mm (1.5689 in)
S67C5073
2
1
S67C5074
S68V5775
a
Valve spring tilt limit
b
:
1.7 mm (0.067 in)
Valve margin thickness
a
:
Intake:
0.6–1.0 mm (0.024–0.039 in)
Exhaust:
0.7–1.1 mm (0.028–0.043 in)
Cylinder head