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Crankshaft and transmission device
Notice in maintenance Check crankshaft
Troubleshooting Check transmission device
Break down crankcase Install crankshaft
Remove transmission system Install transmission system
Remove crankshaft Install crankcase
Notice in maintenance
This section introduce disassembly and assembly of crankshaft and transmission system,
break apart crankcase before working above began. Disassembly for other parts of engine
should be done before breaking apart crankcase.
Working before breaking apart crankcase
Remove engine and lay it on a clean workbench
Drain off lubricant
Remove right crankcase cover
Remove clutch comp.
Remove oil pump comp.
Remove starting spindle comp.
Remove left front cover
Remove magneto comp.
Remove electrical starting gear and starting motor
Remove cover of gearshift device
Remove gearshift arm comp.
Remove check plate comp. and gearshift drum plate
Remove cylinder head comp.
Remove cylinder body comp.
Remove piston comp.
Remove chain, chain adjustor, and tension plate of chain
Specification of each part
Items
标准值（
mm
）
维修极限值（
mm
）
Radial clearance of bigger end of
connecting rod
0.008
～
0.023
0.07
Total clearance between bigger end of
connecting rod and end of crankshaft
0.2
～
0.4
0.6
Thickness of fork and plate of gearshift
drum
4.93
～
5.0
4.83
Diameter of pin of gearshift fork
5.9
～
5.95
5.8
Width of groove of gearshift fork
5.0
～
5.18
5.33
Width of groove of gearshift drum fork
6.05
～
6.15
6.2