I have a 2003 KFX 400 and i overheated it and the rings collapsed. Scorched my piston. Got a new piston and now the rings wont set. so im going to get a Cylinder Works 434cc Big Bore Kit,but I was just curious about if there is any other little things you need to get other then a jet kit. Would appreciate the help thanks!

 

Did you replate the stock jug, or just throw a new piston/rings in it? Dd you check that the head was still true?

Anyways, I put a Cylinder Works kit in my atv last season. They are OK, but the Vertex piston is cast, and mine had a premature catastrophic failure. I was running it pretty hard at the time though. For about the same money you can send your stock jug out to be bored/plated and pick a better piston.

 

I didnt know you could replate it since it was that nickel plating, and i sent head to machine shop to get cleaned up and all that stuff. But i didnt replate it so do you send it out for that? and i have a wesico high compression piston in it now. But if it costs as much as a bore kit to do that i think ill just try a used cylinder of ebay for about 200 bucks

 

Yes, they need to be replated and honed. If you had piston/ring damage then the cylinder was damaged too and is why you have trouble now. The replating is cheaper than a new jug, and even if you buy a used one that would probably need plating and certainly a fresh hone. I hate to say it, but I would put another brand new piston/rings in with the freshened up cylinder.

 

alright thanks man