Yamaha TW200 Service Manual page 103

INSPECTION AND REPAIR
ENG
4. Reface:
-Valve seat
Use a 30°, 45° and 60° Valve Seat Cutter
CD·
lEI
Valve Seat Cutter:
PIN YM-91043
,l"~j
_
When twisting cutter, keep and even down-
ward pressure (4-5 kg) to prevent chatter
marks.
Cut sections as follows
Section
Cutter
A 30°
B
45°
C 60°
Valve seat refacing steps:
IAl
Valve face indicates that valve seat is centered
on valve face but is too wide.
Valve seat cutter set Desired result
Use
30° cutter
To reduce valve
lightly
seat width to
60° cutter
1.0 mm (0.039 in)
[B]
Valve seat is in the middle of the valve face but
too narrow.
Valve seat cutter set Desired result
To achieve a
Use 45° cutter
uniform valve seat
width of 1.0 mm
(0.039 in)
I
I
I
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' 2A
8
A
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