426 is blowing white smoke!!

My babied 02 YZ426 with only 40 original hours on it is starting to blow white smoke. after the last ride I noticed it lost some of its power. Ive heard its the headgasket or valve seals or something along those lines. Is that the issue, and could someone give me a rough span of the repair costs? Thanks guys, RIDE BLUE.

Sounds like a headgasket to me. Burning coolant is usually white. It's either a bad headgasket or a cracked cylinder wall. My money is on the headgasket.

Do you plan to do the work yourself or take it to a shop?

Thanks for the response Zlathim.

originally i planned on taking it to a very reputable guy in town, a friend of mine But, it appears to be a pretty simple fix.

Does the smoke have a particular odor? It's usually pretty easy to destinguish the difference between burning oil and coolant fumes.

If the hours are truly that low, I can't imagine piston/cylinder wear would be an issue.

Does the smoke have a particular odor? It's usually pretty easy to destinguish the difference between burning oil and coolant fumes.

If the hours are truly that low, I can't imagine piston/cylinder wear would be an issue.

One of the regulars here had a low hour '07 that ran something up the bore with the piston and ended up with an audible piston noise and oil consumption, but you're right; it would be rare.

The point about the odor is a good one. Coolant definitely smells distinctively different than oil. Also, coolant "smoke" is actually steam, and like steam, it will tend to disappear into the air (faster when it's warmer out), whereas oil smoke drifts away and dissipates by thinning out. There is reasonably little of either fluid in the system, and the level of one or the other should be dropping noticeably.

thanks for the responses guys. I think it slowly happened over time. at first it was very slight on start up and i was told that it was just moisture in the titanium steaming out. Is this true or was it indeed the coolant leak beginning to get worse and worse?

No way to know, but the clearing of condensed moisture that is common to car exhausts on cold mornings is fairly rare in off-road motorcycle because there isn't as large an internal surface area in the pipe.

In any case, the difference between steam and smoke still applies, and a brief puff of smoke on cold start up is usually a sign of valve guide seals letting oil run down the valve stems while the bike sits.

i just replaced the head gasket in mine. or had it done rather. the head gasket kit is around $35 bucks, i got charged 4 hrs of labor, but i also had my piston, rings and whole head replaced. it would probably be about 2hrs of labor for just the head gasket.

thanks for the responses guys. gotta get it fixed so I can sell it. Two strokes are much more fun! :bonk:

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