Checking The Valve Seats - Yamaha XC50V Service Manual

VALVES AND VALVE SPRINGS
a
b
5-22
EAS00240

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
8 carbon deposits
(from the valve face and valve seat)
2. Check:
8 valve seat
Pitting/wear
3. Measure:
8 valve seat width a
Out of specification
der head.
Valve seat width
Intake: 0.9 ~ 1.1 mm(0.035 ~ 0.043
in)
<Limit>: 1.6 mm(0.063 in)
Exhaust: 0.9 ~1.1 mm(0.035~0.043
in)
<Limit>: 1.6 mm(0.063 in)
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a. Apply Mechanic's blueing dye (Dykem) b
onto the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.
NOTE:
Where the valve seat and valve face contacted
one another, the blueing will have been removed.
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4. Lap:
8 valve face
8 valve seat
NOTE:
After replacing the cylinder head or replacing
the valve and valve guide, the valve seat and
valve face should be lapped.
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ENG
Replace the cylinder head.
Replace the cylin-