Generic Race 50, Service Manual

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163
roundness
- 0.05
Top ring
0.015－0.05 0.09
clearance between the piston ring and
ring groove
Second
ring
0.015－0.05 0.09
Top ring
0.1-0.25 0.5
Joint face clearance
Second
ring
0.1-0.25 0.5
Piston outer diameter
39.97-39.99 39.9
Clearance of cylinder and piston
0.005-0.015 0.1
Piston
Piston
ring
Piston pin hole inner diameter
12.002-12.008 12.04
Outer diameter of piston pin
11.994-12 11.96
Clearance between piston pin hole and piston pin.
0.002-0.014 0.02
Small end inner diameter of the connecting rod.
14.016-14.034 14.06
13.2 Fault diagnosis
Low compression pressure White fume in vent pipe
The piston is worn out
，
burnt out or broken. The piston spring is worn down or damaged
.
The air and cylinder piston is worn out or damaged. The piston and air cylinder is worn out or damaged.
The gasket is damaged; there is air leakage between the crankcase and the gas.
Compression pressure is too high Piston noises
Carbon deposit in the combustion chamber is in overabundance. ·The air cylinder, piston and piston ring is worn out.
·The piston pin hole and piston pin are worn out.
13.3 Cylinder body