In my group of riders we have 3 bikes setup with Trinity 420 kits (like the one in my profile).All 3 are less than a year old and all three have scattered in the last month.

We have done some investigating and found that the pins to hold the rings in place have been over drilled. While the pistons looked ok at install, over time the rings push against the pins, the pins work there way into the piston farther, and then allow the rings to start to move around the piston. As the rings move, they edges get over a intake or exhaust port and... BAM!! the ring breaks!

We have also seen this on a RM250 piston manufactured last year in the same time.

Has anyone else seen this problem? We are looking for more info to go after Wiseco with!

Any info posted here or emailed to banshee@silicontemple.com would be appreciated!!

Thanks
Brad

 

I am not sure if I had wiseco's or OEM's in my banshee, they guy I bought it from said it had new wiseco's.. after examining them I have came to the conclusion that a circlip fell out of the left side and went throught the engine, and I think one of the rings on the other side stuck then broke? here are a couple pictures..
http://www.geocities.com/jibaridge/right.jpg
http://www.geocities.com/jibaridge/left.jpg
like I said, dont know for sure if they were wisecos.. but I just figured I'd throw that in..

 

What was the piston clearance at the time the ring locating pins worked loose???

 

The Pins didn't work loose... they pushed IN to the piston. I'll get the clearance tonight, but the motor had less than 25 hours on it.