Yamaha YFM400FAR, Service Manual

Page: 147 / 481

4 - 24
ENG
CAMSHAFT, ROCKER ARMS AND VALVES
●
Apply a fine lapping compound to the valve
face and repeat the above steps.
NOTE:
After every lapping operation, be sure to clean
off all of the compound from the valve face and
valve seat.
●
Apply Mechanic’s blueing dye (Dykem) to the
valve face.
●
Install the valve into the cylinder head.
●
Press the valve through the valve guide and
onto the valve seat to make a clear pattern.
●
Measure the valve seat width again. If the
valve seat width is out of specification, reface
and relap the valve seat.
*****************************************************
10.Measure:
●
Valve spring free length
a
Out of specification
→
Replace.
11.Measure:
●
Compressed spring force
a
Out of specification
→
Replace.
b
Installed length
Free length (valve spring):
Inner:
39.9 mm (1.57 in)
<Limit>: 37.9 mm (1.49 in)
Outer:
43.27 mm (1.70 in)
<Limit>: 41.27 mm (1.62 in)
Compressed spring force:
Inner:
104.9 ~ 120.6 N at 33.6 mm
(10.70 ~ 12.30 kg,
23.58 ~ 27.11 lb at 1.32 in)
Outer:
235.4 ~ 251.1 N at 36.6 mm
(24.00 ~ 25.60 kg,
52.91 ~ 56.45 lb at 1.44 in)