Valves; Valve Seat Inspection - Yamaha F80A Manual De Servicio Suplementario

POWR

VALVES

Install the new valve guide to the spec-
ified position (from the top of the valve
guide bore as shown) a with the valve
guide remover/installer.
Valve guide position:
11.5 mm (0.45 in)
After installing the valve guide, bore
the valve guide with the valve guide
reamer.
Valve guide reamer:
YM-04066/90890-04066
NOTE:
Heat the cylinder head in an oven to 200 ˚C
(392 ˚F) to ease valve guide removal and
installation, and to maintain the correct
interference fit.
Before installing the valve guide, mark its
installation position b as shown.

Valve seat inspection

1. Measure:
Valve seat width a
Out of specification → Reface the
valve seat.
Valve seat width:
IN: 1.2 ~ 1.6 mm
(0.047 ~ 0.063 in)
EX: 1.2 ~ 1.6 mm
(0.047 ~ 0.063 in)
2. Reface:
Valve seat
CAUTION:
To prevent chatter marks, turn the valve
seat cutter while an even, downward pres-
sure (4 ~ 5 kg).
5-29
E