Should I do the 10.25 piston or stock?

444 · Jun 11, 2009

Well my 02 warrior has started burning a lot of oil while driving. Tailpipe pours blue smoke on a cold start. I bought the quad for a cheap price but you can tell it was ridden hard and put away wet. So I was just going to hone it with my stone hone and do a set of new rings and run it, but boring it and putting in a weisco 10.25 piston does not cost much money either. This will be a good time to replace my seeping side cover seals and add an oil cooler.

My question is, I primarily do rough trail riding, should I do the weisco 10.25 piston or will it run too hot on the trails with the added CR? I think it should be fine with some pump premium gas but would like to hear any personal experiences. Thanks.

20warrior00 · Jun 11, 2009

thats what i got in mine and i run mine on the trails all day with out a oil cooler, i fine it does get a bit hotter but if you jet accordingly and add a oil cooler you'll be fine.

yamarider · Jun 11, 2009

The wiseco piston won't have enough compression to cause a problem, just run premium fuel in it and you'll be fine.

More than likely your thick smoke at startup is not piston rings though, i'd be willing to bet that your valve seals are shot. When the motor cools down after a ride everything contracts slightly as it cools, and old hardened valve seals will not keep sealed and let residual oil drain down into the combustion chamber, then when you fire it up it'll smoke like hell until that burns off. Better change those valve seals while it's apart or you'll be taking it back apart anyways.

sykowarrior357 · Jun 11, 2009

i run it and its fine, i ride in real rough xc terrain, it runs a tad bit hotter but nothing dangerous, plus if you get an oil cooler that will help out even more, you should consider JE piston also, there nice as well.

444 · Jun 12, 2009

YamaRider said:
The wiseco piston won't have enough compression to cause a problem, just run premium fuel in it and you'll be fine.

More than likely your thick smoke at startup is not piston rings though, i'd be willing to bet that your valve seals are shot. When the motor cools down after a ride everything contracts slightly as it cools, and old hardened valve seals will not keep sealed and let residual oil drain down into the combustion chamber, then when you fire it up it'll smoke like hell until that burns off. Better change those valve seals while it's apart or you'll be taking it back apart anyways.

You know I have also been thinking to myself that it could be the valve seals because if it was ring seal it would more than likely be hard to start. I think the first thing I'll do is pull the head and have my local machine shop inspect for valve guide wear, then I can do the valve seals.