Scooterotica

That disappears when clutch engaged? Clues?

Worn clutch bearing or loose nut? Loose endplate? You know you need to take the side case off and see.

Worn out main shim, no oil in case, bad end plate bearing can also cause clutch noise. Like rosscla says, gotta take the case cover off to see what's going on.

I have the same problem on my GP and been advised to add thicker chaincase gasket or thicker washer behind the circlip holding the kickstart shaft in place on the outer side of the chaincase (ie; just behind the kickstart itself) to hold the kickstart out from the 1st gear cog. I am going to strip the bike today and see if there's any signs of 'metal to metal' rubbing. I must confess I did have a few chips on my first gear on the rebuild but dismissed these as a bit of wear over the years..

Nope, completely rebuilt engine with all new bearings and seals. End plate correctly torqued up. New clutch corks soaked for 48 hours. New phosphor bronze clutch bearing. New LI150 gearbox complete. It's not first gear catching on the kickstart either. Fresh ST90 gearoil topped up until overflowed from top drain plug.

Chain alignment?

I put an extra washer on the outside of the chaincase yesterday, between the kickstart and under the circlip and it's pulled the kickstart out from the engine by at least 1mm ....so is better I would say with no sideways movement BUT still a minor sound.......keep on trying I guess.....may grind off the ramp next and use an LI type on the chaincase, see if this helps !!

While it's running try placing a large screwdriver on the case and putting your ear up against it, like a kind of stethoscope, listen at different places might help you track it down.

Chain link pins catching on endplate stud?

Well, had the fecker apart, and stripped down gearbox. No signs of wear anywhere but feck loads of filings on magnetic drain plug. Further examination of parts showed it was the perennial classic of top clutch plate rubbing on kickstart ( it was already ground down a lot, but not enough). Ground some more off. Now have to remove 5 Cwt of filings off drain plug. Just got to sling the fecker back together and hope to feck the kickstart doesn't snap