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XII
Crankcase
Service Data 12.1
Fault Diagnosis
12.2
Crankcase
12.3
Clutch 12.4
12.1 Service Data
Function of crankcase:
It is a bearing component in the engine. It is provided to support the crankshaft, clutch, gearbox, cylinder block
and cover, withstand impact from combustion and inertia force due to crankshaft connecting rod mechanism,
and it also forms some enclosed spaces (oil-seal and gas-seal).
Suspension hole is provided on the crankshaft, and it is connected with the suspension hole on the motorcycle
so that the engine is connected with frame and other parts.
Precautions
Crankcase is thin-wall casting, so it is required to avoid impact during operation for fear of deformation or
breaking.
All parts must be cleaned before being checked, and purged with high-pressure air.
Prior to any operation, release lubricating oil from the crankcase.
Standard Value and Allowable Limit of Reference Items
Unit: mm
Item
Standard value
Allowable limit
Crank linkage
assembly, clutch
Right-left stroke of
connecting rod large end
0.1-0.30
0.5
Radial stroke of connecting
rod large end
0.002-0.010
-
Run-out
0.03
0.03
Friction plate thickness
2.8-2.9
2.8-2.9
Driven friction plate flatness
0.04
0.04
Pressure spring length
30.4-31.6
30.4-31.6
Needle bearing thickness
1.88-2
1.88-2
Shifting
mechanism
Fork shaft outer diameter
11.976-11.994
11.95
Fork bore diameter
12-12.018
12.05
Fork thickness
4.993-5
4.7
Shifting hub outer diameter
35.8-36
35.75
Shifting hub lock slot width
7.1-7.2
7.35
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