Transmission

TRANSMISSION Heavyweight Models

Front chain adjustment. The Scrambler Models use a chain adjuster on each side of the gear box, to prevent the gear box from moving.

Remove the engine plate cover, also inspection cap on chaincase.

Slack off the clamp bolt.

To tighten the chain: Screw down the adjusting bolt. Press down the rear chain to pull the gear box backwards,

Check the chain tension, which, if correct, should have a whip of a".

If the chain is too tight, unscrew the adjusting bolt a little at a time, until the adjustment is correct.

Check the tension in several places. Chains do not always stretch evenly. Retighten the nuts.

Now check the rear chain adjustment. Chain case oil level. With the machine vertical and on both road wheels, the bottom run of the chain should just touch the oil. Rear chain adjustment (quickly detachable wheel). To take up slack or tighten the rear chain and with the machine on the central stand;

Release slightly the spindle nut (22) and the dummy spindle nut (20).

Run back the lock nuts on the two chain adjusting bolts through fork ends, unscrew each adjusting bolt a trifle at a time, also an equal amount, until the chain whip taken in the centre of the bottom chain run is 1 8". Check the tension in one or more places.

As an alternative and possibly the best method is to have this adjustment made with the machine on its road wheels and the rider seated, when the chain whip should be ½". Retighten the release nuts when the adjustment is correct, then check the rear brake adjustment, which will be affected when the wheel position is altered. Rear chain adjustment (non-quickly detachable wheel). Release the spindle nut (1) and adjust the chain as already described, Removing the front chain. Follow details for removing engine from frame. When refitting the chain the closed end of the spring link should face the direction of rotation, Removing the rear chain. The rear chain is closely shrouded by the chain guard, which leaves little room to operate, other than releasing the chain guard from its fixings. If a new chain is to be fitted, disconnect the connecting link in the fitted chain and connect it to the new chain at the top run. Select a neutral position in the gear box then with the left hand holding the bottom chain run and the top with the right hand, the new chain can be pulled into position until the chain joint is accessible, when the connecting link can be fitted. NOTE—The closed end of the spring link should face the direction of rotation.

If a second chain is not available, use a piece of string 10 ft. long, take out the connecting link and pass one end of the string through the link hole. Pull on the string until both ends meet and tie them together.

Pull on the bottom run of the chain, with one hand, keeping the string taut with the other hand.

As the chain leaves the gear box sprocket, the string will be each side of the sprocket teeth.

When the chain is well clear, cut one piece of the string about one foot from where it passes through the chain.

Detach the chain, leaving the string in position. To refit the chain. Pass the longer end of the string through the chain and tie the ends together. Now pull on the string, guiding the chain until it encircles the gear box sprocket. Continue pulling until the top run encircles the rear wheel sprocket and fit the connecting link.

Lightweight Models

Front chain adjustment. Remove inspection cap from front chaincase; remove the two securing screws on the rear engine cowling; lift the cowling to expose the gear box adjuster bolt.

Slacken nut on left-hand side of gear box top fixing bolt.

Slacken two clamping strap bolts.

Adjust chain by means of adjuster eye-bolt 043938 and two nuts. (The correct whip is a".)

Check the adjustment in several positions and adjust at tightest part of chain.

Tighten two clamping strap bolts, top gear box fixing bolt.

Refit rear engine cowling and securing screws.

Replace chaincase inspection cap. NOTE—After adjusting front chain, check rear chain adjustment. Removing the front chain (350 c.c. and 250 c.c. CSR Models). The front chain fitted to this model is duplex and endless, which means that the clutch sprocket, also the engine sprocket must be withdrawn simultaneously if the front chain is to be removed. To proceed, follow the instructions given for dismantling the clutch, as far as removing the gear box mam axle shaft nut. Then remove the nut and washer retaining the rotor to the driving side engine shaft, take out the key for the rotor from the shaft. The engine sprocket and clutch, together with the chain in position, can then be withdrawn. NOTE—One or more shim washers may be fitted at the rear of the engine sprocket, which must be replaced during assembly. Rear chain adjustment. Prior to adjusting rear chain, check front chain and adjust if required.

Loosen both nuts on the rear wheel spindle.

Loosen lock nuts on the adjusters and turn the adjusters until correct chain adjustment is obtained, taking care to move both adjusters exactly the same amount to maintain wheel alignment.

While on the stand the chain whip should be ¾" to ensure ½" whip when rider is seated.

Check the adjustment in several positions and adjust at tightest part of chain.

Remove the rubber cap on the totally enclosed chain guard to check chain tension.

Retighten wheel spindle nuts, and adjuster lock nuts.