Yamaha ttr230 Service Manual page 121

INSPECTION AND REPAIR
A
B
4-27
4. Grind:
• Valve seat
Use 30°, 45° and 60° valve grinders 1.
Valve seat milling cutter:
YM - 91043
CAUTION:
When turning the milling cutter, keep a
4~5 kg pressure.
Mill the seat as follows:
Section
A
B
C
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Valve seat grinding steps
A The valve face indicates that the seat
is centered but too wide.
Milling cutter
30°
60°
B The seat is centered but thin.
Milling cutter
45°
ENGINE
Cutting
30°
45°
60°
Desired result
R e d u c e t h e s e a t
width to 1.0 mm
Desired result
Establish an 1.0 mm
wide uniform seat