
POWR
Power unit
5-31
63P3F11
Checking the valve seat
1. Eliminate carbon deposits from the valve
with a scraper.
2. Apply a thin, even layer of Mechanic’s
blueing dye (Dykem) onto the valve seat.
3. Lap the valve slowly on the valve seat
with a valve lapper (commercially avail-
able) as shown.
4. Measure the valve seat contact width
a
where the blueing dye is adhered to the
valve face. Reface the valve seat if the
valve is not seated properly or if the valve
seat contact width is out of specification.
Replace the valve guide if the valve seat
contact is uneven.
Refacing the valve seat
1. Reface the valve seat with the valve seat
cutter.
2. Cut the surface of the valve seat with a
45° cutter by turning the cutter clockwise
until the valve seat face has become
smooth.
Valve seat contact width
a
:
Intake:
1.1–1.4 mm (0.043–0.055 in)
Exhaust:
1.4–1.7 mm (0.055–0.067 in)
Valve seat cutter holder:
90890-06316
Valve seat cutter:
30° (intake): 90890-06327
30° (exhaust): 90890-06326
45° (intake and exhaust):
90890-06325
60° (intake and exhaust):
90890-06324
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