Scooterotica

could be that the top friction plate is riding over the top of the crown wheel now and again. This can happen if the top steel is too thin, you can buy different thickness ones!
I only say that as you say it happens after you have sat with the clutch pulled in for a while as when the clutch is pulled in the plates are free to move about and if the top steel is too thin the top friction plate is more likely to ride over the top of the crown wheel when the clutch is pulled in!

it then wedges between the top of the crown wheel and the top steel which makes it drag, the grinding noise could be the ears on the friction plates scraping and dragging across the top of the crown wheel till it gets to the next notch and falls back in to place.


PS: is there a prize for who ever gets the diagnosis correct?

Worth checking the chain isn't rubbing on an endplate stud when the clutch is used.

Yes there is a prize. It will probably be the top steel plate as that seems to me to be the culprit. Its the standard original one, but looks like i really shouldve checked the clearance. that does make sense though, and I reckon Ill have to pull the case definitely now. wanted to check chain tension again anyhow so there we go!
I was never really happy with the fit of the kickstart shaft, but im pretty certain its not rubbing. will check that too.
will also check endplate studs for rubbing, do hope its not that though that could well end in catastrophic failure!

cheers all, that's alot of stuff to go with, i certainly feel more comfortable routing around knowing what to look out for.