Yamaha YBR125 Custom, Service Manual

Page: 89 / 218

ENG
Check and repair
4. Grind:
Working face of air valve
Air valve seat
Note:
After replacing air valve and guide pipe of air valve,
grind the air valve seat and working face of air valve.
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Grinding procedure
Paint rough abrasive sand on working face of air valve.
Note:
Do not let the abrasive sand enter into slit between
air valve rod and guide pipe of air valve.
Paint disulfide containing moly on surface of air valve
rod.
Fit the air valve into cylinder cover.
Rotate the air valve until the working face of air valve
and air valve seat polish evenly.Then wipe off all san-
ding agent.
Note:
In order to get better grinding effect,when rotating the
air valve forward and backward with hands,you may
beat the air valve lightly.
Paint fine sand agent on working face of air valve.
Then repeat above procedures.
Note:
After each grinding,wipe off the sanding agent on
working face of air valve and air valve seat.
Measure the air valve seat width again.
If the air valve width exceeds specified value,
repair and grind air valve seat.
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