Here are some notes from changing over a clutch from a tuned scooter with 16,000Km on the clock.

The clutch "bell" has also been strengthed with 4 extra rivets.

The holes are drilled with a 3.2mm (1/8 inch) carbide drill and then the rivets are custom made to fit the holes perfectly. The key is a fit with no movement. My friend Jeremy did the work and said drilling the steel was quite hard. The exact position of the holes are not critical but the rivet fit is.

When we pulled out the clutch though the existing rivets were in good condition. There was minor wear though on the clutch plate "steels" teeth and the corresponding cog they fit into. Below shows a new cog top and old bottom. We replaced these as part of the clutch plate change.

On a much more thrashed scooter, where the rivets did break, the above wear was much more noticable.

Theory to Test: