Yamaha EH63 Service Manual page 81

VALVES
a
a
Valve stem length (Intake):
79.8 mm (3.1417 in)
Valve stem length (Exhaust):
80.3 mm (3.1614 in)
Valve head diameter (Intake):
34.99–35.01 mm (1.3775–1.3783 in)
Valve head diameter (Exhaust):
30.9–31.1 mm (1.2165–1.2244 in)
Out of specifications  Replace.
2.
Measure:
• Valve stem diameter "a"
Valve stem diameter (Intake):
5.970–5.985 mm (0.2350–0.2356 in)
Valve stem diameter (Exhaust):
5.970–5.985 mm (0.2350–0.2356 in)
Limit (Intake):
5.940 mm (0.2338 in)
Limit (Exhaust):
5.940 mm (0.2338 in)
Out of specifications  Replace.
3.
Measure:
• Valve stem runout
Valve stem runout limit:
0.01 mm (0.0004 in)
Out of specifications  Replace.
TIP
The value is half of that indicated on the dial indicator
gauge.
4.
Measure:
• Valve spring free length "a"
Valve spring free length (Intake):
36.5 mm (1.4370 in)
Valve spring free length (Exhaust):
36.5 mm (1.4370 in)
Limit (Intake):
34.67 mm (1.3649 in)
Limit (Exhaust):
34.67 mm (1.3649 in)
Out of specifications  Replace.
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