Jianshe JS125-6B, Maintenance Manual

Page: 83 / 210

ENGINE
73
4. Measurement
Piston-to-cylinder clearance
Note
Cylinder and piston
1. Clean
Carbon deposit
(From the top of piston and ring groove )
2. Check
Piston side wall
Wear, scratching and damage Replace
3. Check
Cylinder wall
Wear or scuffing Bore cylinder once more or
replace
Measure the cylinder bore in the two directions, one
parallels to the crankcase, one squares to the crankcase,
and then demand an average value.
Measuring steps
1. Measure the cylinder bore C with a bore gauge.
The position of D3,D4 (40mm distance from the top
of cylinder)
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Out of specification Replace
Cylinder inside diameter standard:
54.024 54.056 mm
2. Measure the piston
Measure the piston skirt diameter with micrometer
calipers, and measure it at the distance of 5.0 mm
away from the bottom margin of the piston.
Piston outside diameter standard:
53.997 54.029 mm
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