The Primary drive takes the crank rotation and connects it to the clutch with a reduction chain gear; in this case, a duplex chain. The chain has no split links, so replacement is only possible by removing both sprockets as a pair and then fitting a new chain on the bench, before replacing the whole assembly back on the bike.
The primary chain can be accessed by removing the left side engine cover. It is worth draining the gearbox oil first and the gear lever and kickstart must be removed.
A worn primary chain can be confirmed by pressing the top run and seeing how much slack there is. The chain shown here was producing noticeable rattle.
All 6 clutch springs need to be removed by compressing the springs and removing each locking pin in turn.
The tool to do this, was made from a piece of 8mm pipe with a notch cut in the end. A file handle was added for comfort.
Then the clutch clutch plates can be removed from the basket....
....followed by the thrust rod.
One method to stop the engine from turning is to put some string in the bore, through the spark plug hole.
With the engine held, the pinion nut in the end of the crank can be undone (right handed threaded).
The inner clutch reel has to be held whilst the centre nut is undone. The photo shows a homemade tool which was used to lock the inner reel to the clutch basket.
The drawing for the tool is shown above. It is made from a circle of 25 holes which was then bored out on the lathe. Click for a printable image.
The clutch nut has a left -handed thread, so clockwise to undo.
The crank pinion is held to the crankshaft with a taper. To break the taper fit, a puller is needed and the pinion has a 26mmx1.5mm external thread which can be used for this purpose.
Pinion extractor tools are available or there is a drawing for a suitable design given above. Click for a PDF.
With the pinion released, it should be possible to withdraw both sprockets and the chain.
With the new chain fitted, the slack should be noticeably less.
The clutch centre nut should be torqued up to ~65Nm. Check that your torque wrench works anti-clockwise, some don't!
Ensure that when the clutch plates are replaced, the first one in the basket is the metal chamfered one, orientated as shown.
The outer clutch cover should be orientated so that the dimple of the cover aligns with the punch mark on the inner clutch wheel.
Closer view of the inner clutch punch marking.
Easiest Website Builder