ATV 250 Service Manual page 175

2)Check
Flexibility of chain tensioner
Checking procedure
.Press the tensioner pushing rod lightly with
finger, ad rotate it clockwise with thin screw-
driver to screw it in.
.Press the pushing rod lightly with finger and
remove the screwdriver, then the pushing rod
screws out stably
.If the operation is unflexible, replace chain
tensioner.
13.Valve cover and sproket cabinet cover
1)Check
.Valve cover (upper valve cover ¢Ùand lower
valve cover ¢Ú )
.spocket cabinet cover ¢Û
.O-ring ¢Ü
Replace it if there is crack and damaged
14.Cylinder and piston
1)Check
.Carbon deposit (from piston top to ring slot)
2)Check
.Surface of cylinder and piston
Rebore cylinder or replace cylinder and piston
if there is vertical scratch.
3)Measure
.Clearance between cylinder and piston
Measuring method is as following
.Measuring the inner diameter "C"of cylinder
with inner diameter gauge@is the measuring
position @is 40mm(1.6 in)far away from cyl-
inder top
Remark:
Measure twice the inner diameter "C"of cyl-
inder from two directions vertical with each
other in the same face. Then find out average
value.
Wear limit value
Standard value
70.97-71.02mm
71.10mm
Inner diameter
(2.794~2.796 in) (2.799 in)
"C"of cylinder
X+r
C=
2
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