8 -
Final drive
1
Circlip
2
Nut with left-hand thread
3
Washer
4
Nut
5
Rear sprocket flange
6
Washer
7
Bush
8
Bush
9
Cush drive bush
10
Rear sprocket
11
Seal
12
Collar
13
Chain
14
Front sprocket
15
Bolt
16
Front sprocket retaining plate
17
Bolt
18
Front sprocket cover
 Parts catalogue
GEARBOX
REAR WHEEL AXLE
 Important
Bold reference numbers in this section identify parts not shown in the figures alongside the text, but which can be found in the exploded view diagram.
Inspecting the final drive
To check wear of the final drive, carry out a visual inspection of the front sprocket (14) and the rear sprocket (10). If the teeth are found to worn as shown in the figure (dotted line), the sprocket must be renewed.
To check the amount of wear on the chain (13), keep the chain taut and measure 16 links.
If the length (L) is greater than 254 mm, the chain should be renewed.
 Important
The rear sprocket (10), front sprocket (14) and chain (13) must all be renewed together.
Removal of the front sprocket
Remove the LH footrest bracket assembly as described in Section H 4, Removal of the footrest brackets.
Undo the bolts (17) and remove the sprocket cover (18).
Slacken the chain (Sect. D 4, Adjusting the chain tension).
Engage a low gear and unscrew the two screws (15) on the sprocket retaining plate (16).
Remove the retaining plate (16) from the gearbox output shaft.
Slide the front sprocket (14) with the chain (9) off the gearbox output shaft and take the chain (13) off the sprocket.
Refitting the front sprocket
Check that the splines of the gearbox output shaft and the sprocket are in perfect condition.
Hook the chain (13) onto the sprocket (14).
Install the front sprocket on gearbox output shaft (B) as shown in the figure. Push the sprocket beyond the groove (A).
Fit the sprocket retaining plate (16) to the gearbox output shaft (B) and turn it in the groove (A) until the holes in the plate (16) are aligned with the threaded holes in the sprocket (14): position the retaining plate with the rounded edge facing the sprocket.
Apply threadlocker to the threads of the screws (15).
Engage first gear.
Tighten the screws (15) to the specified torque (Sect. C 3, Frame torque settings).
 Important
Adjust the chain tension as described in Section D 4, Adjusting the chain tension.
Fit the sprocket cover (18) and tighten the bolts (17) to the specified torque (Sect. C 3, Frame torque settings).
Renewal of the oil seal on the gearbox output shaft
 Notes
For clarity, the figures show the engine removed from the frame. The procedure can also be carried out with the engine installed in the frame.
 
After removing the front sprocket as described previously, prise the oil seal (11) out of the crankcase with the aid of screwdriver.
 Important
The old oil seal and O-ring must be discarded and new ones fitted on reassembly.
 
Install the bush of service tool no. 88713.2060 on the output shaft. Lubricate the new oil seal (11) and press it into position.
Using the drift of the tool, drive the oil seal home so that seats against the crankcase bearing.
Refit the front sprocket as described in the previous paragraph.
Removal of the rear sprocket
 
Operation
Section reference
Slacken the chain
D 4, Adjusting the chain tension
Remove the rear wheel
G 4, Removal of the rear wheel
Remove the circlip (1) from the nut (2).
Restrain the stub axle against rotation and, using a socket wrench, loosen the nut (2).
Fully unscrew the nut (2) and remove the washer (3) and the flange (5) complete with the rear sprocket.
Recover the collar (12).
Using a mallet, tap the sprocket flange (5) with the cush drive bushes (9) off the sprocket (10).
Check the cush drive bushes (9) for signs of wear and, if necessary, remove from the sprocket flange and renew them.
Refitting the rear sprocket
Refitting is the reverse of removal; ensure that all mating surfaces and the undersides of the retaining nuts (4) of the cush drive bushes (9) are lubricated with the recommended grease.
Check for wear following the instructions given at the beginning of this section.
Insert the rear wheel stub axle (C) in the hub (D).
Install the tapered spacer (6) on the axle (C), with the tapered side facing the axle, as shown in the figure.
Fit the chain (13) to the rear sprocket (10), inserting the sprocket teeth in the chain links.
Fit the sprocket (10) on the axle.
Fit the washer (3) on the axle.
Apply grease to the axle thread and to the contact face of the nut (2).
Fit the nut and tighten it to the specified torque (Sect. C 3, Frame torque settings).
Install the safety clip (1), positioning it on the nut (2) as shown in the figure.
 
Operation
Section reference
Refit the rear wheel
G 4, Refitting the rear wheel
Adjust the chain tension
D 4, Adjusting the chain tension
Washing the chain
Chains with O-rings must be washed in oil, diesel fuel or paraffin (kerosene).
Do not use petrol, trichloroethylene or other solvents, which could damage the rubber O-rings. For the same reason use only sprays specifically formulated for use with O-ring chains.
Lubricating the chain
Chains with O-rings are lubricated and sealed to protect the O-rings themselves against wear in the pin/bushing area. However, these chains need lubricating at regular intervals to protect metal parts of the chain and the O rings.
Lubrication also serves to keep the O-rings soft and pliable to ensure the maximum sealing efficiency.
Using a brush, apply a thin protective film of high-density engine oil along the entire length of the chain both inside and outside (see specifications in Sect. C 2, Fuel, lubricants and other fluids).