Don't worry the dog hair in the first pic didn't cause this
..what oil you using, pete?
Well, was using amsoil for a long time. Recently switched to... I'll have to go look. sh**, I just threw away the bottle the other day. Bought it at a Polaris dealership. Supposed to be good stuff. Was supposed to have less odor. I'm not sure if it did or didn't. Either way I don't really attribute that to it. Look the pics and you'll see.
The rings caught the exhaust port. Short story, a little while before it blew up it started running really funny. Would idle fine, but would break up at WOT. After trying everything I could think of I finally just tore down the top end and in the process found a shot exhaust gasket. The piston, rings, and cylinder all looked good... really good, so I replaced all the gaskets and cleaned up the carbon build up in the exhaust port. Got it back together and it ran good again. About a month later complete compression loss.
First off let me state I have never taken the time to chamfer all the ports on my new cylinders. I know I should have. I guess I figured if I spent 200 f'in dollars it should be fine to just bolt on. Like most of us on here I learn as I go. At the time of the install I didn't know I was completely oblivious.
So, here's what I think happened. As I said I cleaned the carbon out of the exhaust port like any logical thinking person would. When I think back the carbon was built up around the edge of the port. In essence acting as a guide for the rings as the rings moved past the port. When I cleaned the carbon out it allowed the rings to snag the port as I assume it had been until the carbon built up. The rings simply couldn't take any more of it and from the looks of it it snagged one good time and obliterated the rings. Actually I'm surprised the piston is still in one piece. That didn't happen the first two times.
I should also say that my factory piston and cylinder failed in the exact same way. hmmmm.... Yeah...
