Yamaha F150B - Checking the Valve Spring; Checking the Valve

7-39
Power unit
POWR
Checking the valve spring
1. Measure the valve spring free length a.
Replace if out of specification.
2. Measure the valve spring tilt b. Replace
if above specification.
Checking the valve
1. Check the valve face. Replace if pitted or
worn.
2. Measure the valve margin thickness a.
3. Measure the valve stem diameter b.
Replace if out of specification.
4. Measure the valve stem runout. Replace
if above specification.
Cylinder head warpage limit:
0.1 mm (0.0039 in)
Valve spring free length a:
44.2 mm (1.74 in)
Valve spring tilt limit b: 1.2 mm (0.05 in)
a
b
a
Valve margin thickness a:
Intake:
0.70 mm (0.0276 in)
Exhaust:
1.00 mm (0.0394 in)
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)
Valve stem runout: 0.01 mm (0.0004 in)
b