Abnormal sound in the crankcase

There are parts scattered or broken inside the crankcase

Engine stalling

Clutch is stuck

Shifting difficulty

Separation between the clutches is not complete

Poor returning spring of the clutch

Locked grove of the gearshift hub worn

Crankcase

Disassemble the left cover of the crankcase

Release the fastening bolts of the starting engine to remove the starting engine.

Release the fastening bolts of the left cover to remove the left cover.

 

Release the locking nuts of the flywheel using electric or pneumatic tools.

Allocate the flywheel assembly (including the star wheel) to remove the electric idle gear.

Remove the gasket.

 

Disassemble the right cover of the crankcase

Loosen the fastening bolts to remove the right cover of the crankcase, gasket and locating pin.

 

Clutch

Removal

Loosen the five bolts of the pressure plate according to the diagonal cross mode.

Remove the clutch springs, spring washers, pressure plate, bearing washer, surface needle roller bearing and bearing pedestal, clutch separation shaft sleeve and so on.

 

 

Use a special tool to screw off clutch locknut. Remove locknut and washer.

Remove clutch center bracket.

Remove clutch drive and driven friction plates.

Removed components refer to exploded view.

 

Remove the thrust washer.

Remove housing assembly.

 

Install clutch in the reverse order of removal.

Disassemble Clutch

1 Bolt 2 Spring washer 3 Clutch spring 4 Pressure plate 5 Bearing washer 6 Surface needle bearing 7 Clutch separation shaft sleeve 8 Jam nut 9 Locking washer 10 Friction plate assembly 11 Driven plate 12 Clutch driven hub 13 Thrust washer 14 Clutch driving drum assembly 15 Internal separation mandrilЎ 16 Needle roller bearing 17 Bushing 18 Internal separation mandril¦т 19 Separation drag bar weld assembly 20 Clutch assembly
Inspection

Check if there are burs or broken parts on the housing groove of clutch. If there are, fix and adjust with a file.

If there is a lot for fix and adjustment, replace it.

 

 

Check if teeth of pressure plate and center bracket are injured. If they are, replace them.

 

 

Measure the free length of pressure spring.

Allowable limit: replace it if below 29.7mm.

 

Measure the thickness of friction plate with a vernier caliper.

Allowable limit: Replace it when below 2.5mm.

 

Check the flatness of the driven friction plate with the plug gauge.

Allowable limit: Replace it if above 0.2mm.

 

measure the thickness of the surface needle roller bearing.

Allowable limit: Replace it when it is below 1.8 mm.

Crankshaft connecting rod combination and variable speed chamber

Gearshift mechanism

Disassemble

Remove the stop arm.

Remove the gearshift locating plate.

Remove the gearshift shaft combination

Remove the parts.

(Please refer to the exploded view of the
variable-speed shift assembly)

 

Inspection

The gearshift plate should be pulled back flexibly without clamping stagnation before being disassembled.

Check whether the gearshift plate and the gearshift shaft combination are worn. If badly worn, replace it.

Check whether the gearshift locating plate is worn. If badly worn, replace it.

Check whether the gearshift shaft is bent. If excessively bent, replace it.

Check whether the force of the return spring is weakened, and replace it if necessary.

 

 

Loosen the nuts and washer of the right crankshaft to remove the clutch drive gear using electric or pneumatic tools.

 

Remove the nuts of the countershaft to remove the sprockets and bushings.

Loosen the mould assembling bolt.

Separate the crankcase.

Attention: There should be no damage on joint case surface.

Remove the left case.

 

 

Crankcase connecting rod combination

Disassemble

Remove the trunnion shaft combination and crankcase connecting rod combination from the right crankcase.

Attention: There should be no damage on joint case surface.

 

 

 

 

Inspection

Measure the clearance between the big ends of connecting rod.

Allowable limit: 0.5 mm.

 

 

Measure the clearance in the X-Y direction of the big ends of connecting rod.

Allowable limit: 0.008-0.018mm.

 

Measure the jumping of the crankshaft.

Allowable limit: 0.03 mm.

 

Check whether there is abnormal sound or loose for the revolution of the crankshaft bearing. If any, replace the crankshaft assembly.

 

Set aside the shifting fork shaft.

Remove the gearshift drum.

Remove the gearshift fork.

 

Inspection

Measure the outer diameter of the shifting fork shaft.

Allowable limit: 9.96mm.

 

Measure the inner diameter of the shifting fork hole.

Allowable limit: 10.05mm.

 

 

Measure the thickness of the shifting fork.

Allowable limit: 4.6mm

 

Measure the outer diameter of gearshift drum.

Allowable limit: 41.75mmЎЈ

Measure the width of the locked groove of the gearshift drum.

Allowable limit: 5.7mm.

 

 

13.7 Variable speed chamber

Remove the spindle assembly.

Remove the layshaft assembly.