I had the exhaust side skirt break off of the exhaust side of my piston, it was a standard sized cast piston with ART on the inside, supposed to be a pro-x. In my case the cylinder was way to worn, but it looks like they honed it and threw a piston in anyway.
I got about 15 or so hours on it before, upgrading my pipe, first time I tached it out hard then grabbed the next gear, smack that piston couldn't take it, the only thing that saved me from beating it all to hell is a piece of cast flew up into the spark plug and fouled it out. It probably the only thing that saved it the motor had all but quit and made one crunchy sounding rotation and the got locked by cast aluminum between the rod and the case , guarenteed if it would have been at WOT spinning 7 or 8k rpm it would have busted a hole in the case.
So I split the cases and cleaned them out I couldn't believe how much aluminum grit was in the crankcase from just one piston skirt.
Even after splitting the cases removing the seals ,using kerosene, carb cleaner,compressed air, brake kleen,wd-40, a pick, etc. I still couldn't get all the grit out of the main bearings and had to replace them. I hated to replace them as they were same as new, as was the wiseco crank set.
Anyhow if the cases aren't split and cleaned out properly the best you can hope for is that you were able to get enough out to keep from destroying the next piston, but even then you got 2 to 10 hours before you loose a bearing to the shavings that are definitely going to be left in them.
Get the service manual, watch some Ken O' Conner vids on teardown and building, then find a table in you garage clear it off put down a white to well or two. Order a clutch /flywheel holding tool, and a flywheel puller.
And get that motor stripped down, out of the frame and split in two.
When you get It going again, it will be with a different sort of pride.
