Checking The Valve Seat - Yamaha F15B Service Manual

POWR
3. Insert the special service tool into the
valve guide 2, and then ream the valve
guide.
NOTE:
9 Turn the valve guide reamer clockwise to
ream the valve guide.
9 Do not turn the reamer counterclockwise
when removing the reamer.
Valve guide reamer:
90890-06804
4. Measure the valve guide inside diameter.
Replace the valve guide if out of specifi-
cation.
Valve guide inside diameter:
5.500–5.512 mm
(0.2165–0.2170 in)

Checking the valve seat

1. Eliminate carbon deposits from the valve
with 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 valve lapper (commercially obtain-
able) as shown.
5-27
Power unit
2
6D450630
6D450640
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.
Valve seat contact width a:
Intake:
0.60–0.80 mm (0.0236–0.0315 in)
Exhaust:
0.60–0.80 mm (0.0236–0.0315 in)
Valve lapper:
90890-04101
6D450650
6D450660
6D45F11