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5. Remove the connecting rod bolt and connecting rod cover, remove the crankshaft, and
then remove the connecting rod and piston assembly.
6. Remove the piston pin circlip with pliers, then remove the piston pin and the piston.
7. Remove the oil seal, locating pin and bearing bush.
Piston
1. Measure the piston outer diameter at the specified measuring point.
If the specified value is not met, replace it.
Diameter of piston: 64.950～64.965 mm
Measuring point○a : 5mm
2. Check the inner diameter of piston pin bore.
If the specified value is not met, replace it.
Inner diameter of piston pin bore: 15.974~15.985mm
Cylinder bore
1. Measure the piston outer diameter ○1 , ○2 and ○3 at the specified measuring point.
At each measure point, six diameters parallel to the crankshaft direction D1, D3, D5
and perpendicular to the crankshaft direction D2, D4, D6 are measure respectively.
Height of measuring point ○1 20 mm;
○2 60 mm;
○3 100 mm
Cylinder bore: 65.000～65.013 mm
2. Calculate the taper limit and roundness limit. If the specified value is exceeded, replace
the crankcase.
taper limit: 0.08 mm (D1-D5, D2-D6)
Roundness limit： 0.05 mm (D2-D1, D6-D5)
Piston pin outer diameter
Check the piston pin outer diameter; If it does not conform to the specified value, replace
it.
Piston pin outer diameter: 15.965～15.970 mm
Piston ring
1. Check the piston ring cross-sectional dimensions. If the specified value is not met,
replace it.
Thickness Section width
Top ring
1.17～1.19 mm 2.39～2.41 mm
2
nd
ring 1.47~1.49mm
2.49～2.51 mm
Oil ring
2.34～2.46 mm
2.75mm
2. Push the piston ring parallel into the cylinder with the piston to the specified measuring
point (20mm from the joint surface).
3. Measure the end clearance of piston ring with clearance gauge; If it does not conform to
the specified value, replace it.
End clearance (when installing) Top ring 0.15 ~ 0.30 mm
2
nd
ring 0.30～0.50 mm
Oil ring 0.20 ~ 0.70 mm
a
D
②
③
①
D1&D2
D3&D4
D5&D6
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