Sorry, there was only 80 miles on the rebuild. There is no compression on the clutch side piston and the other piston compression is fine. The spark plug on the clutch side is grey with metal fragments and the other plug is reddish brown. So, why is the clutch side piston burning up all the time. This is now the second time that the piston has melted.
Did you replace the crankshaft seal when you did the rebuild? That's another common place for an air leak. Also, check to make sure the main jet on that side carb isn't clogged or varnished, making the jet effectively smaller in size, resulting in a lean condition.
I have a 1992 Polaris Indy 500 that consistantly is burning up on piston in one cylinder. It will run about 20 miles or so and bog down and run on one cylinder, i will then check er out and it ends upthat the one piston (same piston) is rubbed down and looks like a burn hole. like a a groove was worn on it.
I am gonna try and spray some brake fluid on it when she is running cause i have a good piston in her now, see if that cause her to stall so i know its the crank seal.