Checking The Valve Spring; Checking The Valve - Yamaha F150B Service Manual

POWR
Cylinder head warpage limit:
0.1 mm (0.0039 in)

Checking the valve spring

1. Measure the valve spring free length a.
Replace if out of specification.
a
Valve spring free length a:
44.2 mm (1.74 in)
2. Measure the valve spring tilt b. Replace
if above specification.
Valve spring tilt limit b: 1.2 mm (0.05 in)

Checking the valve

1. Check the valve face. Replace if pitted or
worn.
2. Measure the valve margin thickness a.
7-39
Power unit
b
a
Valve margin thickness a:
Intake:
0.70 mm (0.0276 in)
Exhaust:
1.00 mm (0.0394 in)
3. Measure the valve stem diameter b.
Replace if out of specification.
b
Valve stem diameter b:
Intake:
5.477–5.492 mm (0.2156–0.2162 in)
Exhaust:
5.464–5.479 mm (0.2151–0.2157 in)
4. Measure the valve stem runout. Replace
if above specification.
Valve stem runout: 0.01 mm (0.0004 in)