Checking The Valves; Checking The Valve Guides - Yamaha F2.5A Service Manual

2. Measure the valve spring tilt b. Replace
if out of specification.
Valve spring tilt limit b:
1.2 mm (0.05 in)

Checking the valves

1. Check the valve face for pitting or wear.
Replace if necessary.
2. Measure the valve margin thickness a.
Replace if out of specification.
Valve margin thickness a:
Intake: 0.7 mm (0.028 in)
Exhaust: 1.0 mm (0.040 in)
3. Measure the valve stem diameter b.
Replace if out of specification.
69M3E11
Valve stem diameter b:
Intake:
5.475–5.490 mm
(0.2156–0.2161 in)
Exhaust:
5.460–5.475 mm
(0.2150–0.2156 in)
4. Measure the valve stem runout. Replace
if out of specification.
Valve stem runout:
0.03 mm (0.0012 in)

Checking the valve guides

NOTE:
Before checking the valve guide make sure
that the valve stem diameter is within specifi-
cation.
1. Measure the valve guide inside diameter
a.
a
Valve guide inside diameter a:
5.500–5.512 mm
(0.2165–0.2170 in)
Cylinder head
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S69M5350
5-16