I pulled the head off my banshee today to replace the 21cc domes with 19cc domes, and found some damage to the left piston and dome. The marks on them are round, so I know it wasn't a piece of the ring. It looks like a ball bearing, but I don't know where it could have come from. I didn't notice any problems the last time I rode it. I usually ride only 2 or 3 times a year, so I can't tell if it was a little down on power or not. It seemed fine to me.

Here's the pictures

sudweeks.net/banshee

I don't think there's any damage to the cylinder wall. The wall of the left one actually has less marks on it then the right one. But both are pretty smooth. No vertical groves that I can feel. There's also no slop in the either piston.

My questions are --

What was caused the problem? Where could that little bb have come from?
Is it safe to just replace the domes and ride without replacing the piston or inspecting the bottom end?
Also - if the bb came from the carb or something - could that in itself cause me some problems?

Thanks

-Josh

 

You'r right something was in there at one time. I would replace the pistons and domes.

 

What the heck are those spots? My first thought is sabotage. You need too tear it down because you should have some crap in the bottom end. I would go with new pistons, rings, a fresh bore and new domes. Unbolt the cylinder and it will roll right off the front of the engine WITH the crank if you are careful and wanna try and clean things up without the pistons and bore job....not advised though.

 

Well - I just replaced the domes and threw it back together and rode this weekend. Ran great. Maybe I'll wait for a problem before I rebuild it.