Yamaha YBR 125 Service Manual page 90

Check and repair
Air valve and guide pipe of air valve
1.Measure:
Clearance between air valve rod and guide pipe
Clearance between air valve and guide pipe=
Inner diameter of air valve guide pipe
air valve rod diameter
Exceeding specified value range→Replacing guide
pipe of air valve
Clearance between air valve rod and guide pipe:
Intake:
0.01 0.037 mm
Exhaust:
0.025 0.052 mm Limit valve:0.10 mm
Note:
After replacing guide pipe of air valve,repair the sur-
face of air valve seat.
2. Clean:
Carbon deposit
(clean from working surface of air valve)
4 - 21
ENG
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Limit valve:0.08 mm
Standard inner
Using limit
diameter
5.000~5.012mm 5.042mm
5.000~5.012mm
5.042mm