Checking The Valve Seats - Yamaha XVS250 2001 Service Manual

VALVES AND VALVE SPRINGS
5. Measure:
D valve margin thickness a
Out of specification  Replace the valve.
6. Measure:
D valve stem runout
Out of specification  Replace the valve.
NOTE:
D When installing a new valve, always replace
the valve guide.
D If the valve is removed or replaced, always re-
place the valve stem seal.
EAS00240

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
D carbon deposits
(from the valve face and valve seat)
2. Check:
D valve seat
Pitting/wear  Replace the cylinder head.
3. Measure:
D valve seat width a
Out of specification  Replace the cylinder
head.
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 pattern.
d. Measure the valve seat width. Where the
valve seat and valve face contacted one
another, the blueing will have been removed.
5-23
ENG
Valve margin thickness
Intake 0.4 0.8 mm
Exhaust 0.8 1.2 mm
Valve stem runout
0.02 mm
Valve seat width
Intake: 0.9 1.1 mm
<Limit>: 1.6 mm
Exhaust: 0.9 1.1 mm
<Limit>: 1.6 mm