All 2st Lots of white smoke......

My WR 300 had a bad day! It was quite muggy out and I got stuck in some nasty singletrack. After a few spills, I got it out of there and went back down the mountain. When I got back onto a wide open section to clean it out, it was breaking up and billowing white smoke. I rode it about 2 miles home and changed the plug and cleaned out my blocked trans. vent hose. Could trans oil have gotten into the cylinder one of the times it was taking a nap on its side?

Or bad clutch side crank seal has gone out. You should also be able to smell coolant and also notice coolant loss, if you have a blown head gasket. BUT, You do have a major problem that must be addressed before you cause MAJOR damage.

White smoke means either blown head gasket (though the white smoke will dissipate quickly as it's just steam) or flooding (too much fuel). Everything OK with the carb?

I doubt it is oil as oil produces more of a blue-ish tinge smoke and you'll definitely smell it.

Is it possible that the plug was just fouled and it was loading up? I didnt have time to ride it much after I put the new plug in it but it seemed to be much better.

im voting head gasket, warped head due to overheating. sparkplug shouldnt change the color of your smoke, if it does i want a green smoke one! the trans vent line got clogged up on one of our yz125s and bad things happend because of that - including almost taking my hand off when i pulled the drainplug, couldnt believe it built up that much pressure

Oil smoke is white with bluish tinge, Coolant is more white . Running rich or too much fuel is BLACK smoke not white.

I second vinduro, theres been instances of the crankcase seals being installed from the factory backwards causing intermitent amount of trans oil in the crankcase

http://www.thumpertalk.com/forum/showthread.php?t=986179

goodluck

Thanks for all of the replies! I can't say that I'm looking forward to figure it out though.

If your bike spent a significant amount of time on its side, then you may have just gotten a bunch of fuel in the bottom end from overflow from the carb. That would get your plug all foul-y and cause a bunch of smoke. It also might explain why it's all better with the new plug.

God I hope so! I didnt have a chance to ride it since. I'm going to try it out tonight and see what happens.

I finally got to ride it tonight and everything seemed good. Hopefully it is ok now......

bingo- flooded pipe/case. remove pipe, let it drain, pull plug and lower piston....let it air out a couple days stroking the motor slow like by hand one or twice a day (in bad cases like parking for a few days with the gas on and a full tank etc...). careful with these they can bite. seen bent rods from towing behind truck with this condition. take it easy for while till things are right again.

wet crank seal failure = LOTS of smoke, dead plug now and wont clear out.
blow h/g = pushes coolant out rad, SWEET smell out the pipe, rusty plug.

glad she sounds ok!

I rode 45 miles of single track, double track and railroad beds today and she ran like a top. Thanks for the advise as always.