ATV 250 Service Manual page 168

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.Press the valve on through valve guide pipe
to leave clear trace on the valves.
.Remove the valve from cylinder cover
.When the valve contancts with valve race,
the redle is marked on the valve form vavle
race, Then can measure the contacting width
of valve and valve race.
Contactingwidth of valve
and valve race
Intake
0.9~1.1mm
(0.035~0.043mmin)
Exhaust
.If the contacting width is too wide, too nar-
row or not in the middle, it is necessary to
recorrect valve race
4)Correct
.Valve race
Use reamers of30¡ã .45¡ã and60¡ã
Caution
Rotate the reamer with even force to avoid
cutting mark. And remove surplus part to get
ideal valve race.
Reamer used on each part
Part
A
B
C
Valve race correcting procedure
The contacting part A is in the middle of valve
face. But the contacting width is too wide.
Reamer assy of valve race
Reamer 30¡ã
Operate
lightly
Reamer 60¡ã
Limit
1.6mm
(0.063in)
Reamer
30¡ã
45¡ã
60¡ã
Result
Reduce the contacting
width to 1.0mm(0.04 in)