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Carbon deposit is accumulated on the top of piston and the edge of upper port of the cylinder.
Carbon deposits shall be cleared up before the inspection. Soak the carbon deposit with
kerosene first, and then remove it with a blunt scraper or metal brush.
a) O.D. of piston skirt
Measure the O.D. of the piston skirt by O.D. micrometer, to replace it if it exceeds the service
limit.
Standard
Service limit
94.46-94.47 mm
94.36 mm
b) The clearance between piston pin hole and piston pin
Use the inside micrometer and the outside micrometer to measure the inner diameter of the
piston pin seat hole and the outer diameter of the piston pin respectively. And then calculate
its clearance value based on measured result.
Standard
Service limit
0.002-0.008 mm
0.008 mm
d) Clearance of piston ring side
When inspecting, place each ring in its respective piston ring groove. Piston rings shall rotate
freely, to be neither loose nor sluggish. Then measure by insert a thickness gauge into the gap
between upper and lower planes of the ring and slot.
