YG125-30A Maintenance Manual
Cylinder Head, Cylinder and Piston
67
Piston inspection
Check the piston for abrasion or damage, cracks, etc. and
check the skirt section for scratch.
Measure the piston external diameter at the position
10mm above the piston skirt.
Maintenance limit:
≥φ
84.87mm
Measure the piston pin hole inside diameter.
Maintenance limit:
≤φ
20.05mm.
Measure the clearance between the piston ring and the
piston groove before removing the piston ring.
Maintenance limit: First ring / Second ring
≤
0.12mm, Oil
ring
≤
0.40mm.
Mount the piston rings into the cylinder respectively and
measure the gap clearance. Maintenance limit: First ring
≤
0.65mm, Second spring
≤
0.7mm.
Measure the piston pin external diameter.
Clearance gauge
Maintenance limit:
≥φ
19.98mm
Work out the clearance between the cylinder and piston.
Maintenance limit:
≤
0.10mm.
Work out the clearance between the piston and piston pin.
Maintenance limit:
≤
0.07mm.
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