Refacing The Valve Seat - Yamaha F225F Service Manual

POWR

Refacing the valve seat

After every lapping procedure, make sure
to clean off any remaining lapping com-
pound from the cylinder head and valves.
1. Reface the valve seat using the special
service tools.
30 45
Valve seat cutter holder: 90890-06316
Intake:
Valve seat cutter 30°: 90890-06331
Valve seat cutter 45°: 90890-06332
Valve seat cutter 60°: 90890-06333
Exhaust:
Valve seat cutter 30°: 90890-06327
Valve seat cutter 45°: 90890-06325
Valve seat cutter 60°: 90890-06324
2. Cut the surface of the valve seat using a
45° cutter by turning the cutter clockwise
until the valve seat face has become
smooth. NOTICE: Do not over cut the
valve seat. To prevent chatter marks,
make sure to turn the cutter evenly
using a downward force of 40–50 N
(4.0–5.0 kgf, 8.8–11.0 lbf).
7-59
Power unit
60
45˚
a Slag or rough surface
3. Adjust the top edge of the valve seat
contact width using a 30° cutter.
30˚
b Previous contact width
4. Adjust the bottom edge of the valve seat
contact width using a 60° cutter.
b Previous contact width
5. Adjust the valve seat contact width to
specification using a 45° cutter.
a
b
b
60˚