No.
Fault symptom
Cause analysis
Remark
1
Shift difficulty
The shift fork is bent and deformed
Gaskets and bolts of speed drum loose and
loose
2
Groove-skipping
The pawl of the shift gear is worn
The shift fork is bent or worn
3
Crankshaft noise
The needle roller bearing at the big end of the
connecting rod is worn
Connecting rod bending
The crankshaft bearing is worn
4
Main and countershaft gear
noise
The main and countershaft gears are worn
The spline shaft is worn
Decomposition of crankcase
The decomposition steps of crankcase are as follows:
1. Place the right crankcase of the engine upward, remove the starting shaft retainer ring, remove the starting shaft
return spring and the starting shaft return spring seat;
2. Place the left crankcase of the engine upward; Remove 1 GB/T 5787/ M6x12 bolt and baffle at the hole of the
variable speed drum, take out the rubber plug, take out 1 GB/T 5787/ M6x16 bolt and the washer of the variable
speed drum;
3. Remove 4 GB/ T5787-M6x65 bolts, 2 GB/ T5787-M6x6 bolts and 1 GB/T5787 / M6x50 bolts, turn the
crankcase to separate the left crankcase from the right crankcase, and remove 2 positioning pins and crankcase
gaskets.
Disassembly of crankshaft, main and auxiliary
shaft
Disassembly of crankshaft, main and auxiliary shaft
1. Take out the crankshaft assembly from the box;
2. Take out the fork shaft, fork, speed change drum and
main and auxiliary shaft assembly from the box.
Note:
ensure that no parts are left behind when taking
the main and secondary shaft components.
Decomposition of variable speed drum
The decomposition steps of the variable speed drum are as follows:
1. Remove the spring clip.
2. Pull out the fork pin.
3. Take out the fork
Inspection of crankshaft
