Checking The Valve Seats - Yamaha YP400T Service Manual

VALVES AND VALVE SPRINGS
6. Measure:
• valve stem runout
Out of specification → Replace the valve.
NOTE:
_
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always
replace the oil seal.
EAS00240

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• carbon deposits
(from the valve face and valve seat)
2. Check:
• valve seat
Pitting/wear → Replace the cylinder head.
3. Measure:
• valve seat width a
Out of specification → Replace the cylinder
head.
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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.
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ENG
Valve stem runout
0.01 mm (0.0004 in)
Valve seat width limit
1.6 mm (0.06 in)
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