4 - 23
ENG
INSPECTION AND REPAIR
●Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
●Remove the valve from the cylinder head.
●Measure the valve seat width a.
When the valve seat and valve face make
contact, bluing will be applied to the valve
face.
●If the valve seat width is too wide, too nar-
row, or seat has not centered. The valve
seat must be refaced.
*********************************
Valve seat width Limit
Intake
0.9 ~ 1.1 mm
(0.035 ~ 0.043 in)
1.6 mm
(0.063 in)
Exhaust
4.Reface:
● Valve seat
Use 30˚, 45˚ and 60˚ Valve Seat Cutter.
CAUTION:
Remove just enough material to achieve
satisfactory seat. When twisting cutter,
keep an even downward pressure to pre-
vent chatter marks.
*********************************
Valve seat refacing steps:
Å Valve face indicates that valve seat is cen-
tered on valve face but is too wide.
Valve seat cutter set:
P/N. YM-91043-B
Cut sections as follows
Section Cutter
A 30˚
B 45˚
C 60˚
Valve seat cutter set Desired result
Use
lightly
30˚ cutter To reduce valve seat
width to 1.0 mm
(0.04 in)
60˚ cutter
Å
4