I have recently bought an alleged fully mechanically rebuilt Supa 5.The more I ride it the less I like it.After a 30 minute ride round town at 30 – 45mph the bike now makes a noticeable knocking noise from the lefthand engine cover which disappears when the clutch lever is pulled in. I’ve had 4 previous MZ’s but no Supa 5’s and this is a new noise to me. It should be noted the noise disappears when the engine has cooled down and then restarted. Is this normal or is it a problem.Many thanks.
Most likely it’s because the output gear has not been shimmed properly. Different thicknesses of thrust washer are available to reduce set the clearance. Too big a gap and you get the knocking noise which goes because operating the clutch closes the gap. Very common on rebuilt motors and since the shims are only available in a limited range of sizes, not always possible to get rid of it completely. Its an irritating noise but not life threatening.
To fix it you need to remove the clutch which requires a special puller. I am sure you know not to use a 3 legged puller as advised in the Haynes Manual.
Other possible causes are worn main bearings or a worn clutch support bearing in the outer case.