well i have been doing a top end rebuild on my MC28
and everything was going nice.
until i went to put the new rings on my second piston.

got the bottom one on fine put the top one on and woo it grabbed it like its life depended on it. could not get it to slip around or move freely. and in the end i F'd the ring up trying to get it off.

so ordered a new set of rings which arrived today.
cleaned up the piston and started again.
exactly the same thing happened. the top grove appears to have shrunk ? impossible i know.
it wont even except the original rings and its not like its just tight in one place its tight the whole way round.

never seen anything like it.

so new piston it is and i have to wait a bit longer to get my bike out on the road. ho hum