Yamaha YFM660RN, Service Manual

Page: 209 / 328

5 - 29
ENG
VALVES AND VALVE SPRINGS
●
Install the valve into the cylinder head.
●
Turn the valve until the valve face and valve
seat are evenly polished, then clean off all of
the compound.
NOTE:
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth
between your hands.
●
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.
Free length (valve spring):
Inner:
35.95 mm (1.42 in)
<Limit>: 34.15 mm (1.34 in)
Outer:
37.75 mm (1.49 in)
<Limit>: 35.86 mm (1.41 in)