ATV 250 Service Manual page 166

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3)Measure
.Rod part run-out of valve rod
Replace it if unqualified
The rod part run-out of valve rod is less than
(0.03mm0.0012in)
4)Measure
.Clearance between valve rod and valve guide
pipe
Clearance=A-B
Inner diameter of valve guide pipe A
Valve rod diameter B
Repalce the valve or valve guide pipe if
unqualified.
Measure with micrometer and inner diameter
gauge ¢Ù
Clearance between valve rod
and valve guide pipe
Intake
0.010~0.037mm
valve
(0.004~0.0015 in)
Exhaust
0.025~0.052mm
valve
(0.0010~0.0020 in)
Caution
.When replacing the valve, should replace the
valve guide pipe and valve rod oil seal together.
3.Valve guide pipe
1)Check
.Valve guide pipe
Replace it if it is worn or the oil leaks into the
cylinder
2)Disassemble
.Valve guide pipe
Use valve guide pipe diassembling device¢Ù
Caution
Place the cylinder cover in the furnace to heat
to 100¡æ (212F)for the econvience of disassem-
bly and installation of valve quide pipe. And it
can ensure correct installating clearance.
Limit
0.08mm
(0.0031 in)
0.10mm
(0.0039 in)