Checking The Valve Springs - Yamaha YZF-R1P Service Manual

VALVES AND VALVE SPRINGS
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a. Apply a coarse lapping compound a to the
valve face.
CAUTION:
_
Do not let the lapping compound enter the
gap between the valve stem and the valve
guide.
b. Apply molybdenum disulfide oil onto the
valve stem.
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
seat are evenly polished, then clean off all
of the lapping compound.
NOTE:
_
For the best lapping results, lightly tap the
valve seat while rotating the valve back and
forth between your hands.
e. Apply a fine lapping compound to the valve
face and repeat the above steps.
f. After every lapping procedure, be sure to
clean off all of the lapping compound from
the valve face and valve seat.
g. Apply Mechanic's blueing dye (Dykem) onto
the valve face.
h. Install the valve into the cylinder head.
i. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
j. Measure the valve seat width a again. If
the valve seat width is out of specification,
reface and lap the valve seat.
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EAS00241

CHECKING THE VALVE SPRINGS

The following procedure applies to all of the
valve springs.
1. Measure:
• valve spring free length a
Out of specification → Replace the valve
spring.
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Valve spring free length
Intake valve spring
38.9 mm (1.53 in)
<Limit: 37.0 mm (1.46 in)>
Exhaust valve spring
40.67 mm (1.60 in)
<Limit: 38.6 mm (1.52 in)>
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