[jmoffett]

i just bought my son a 2000 yamaha ttr-90 dirt bike. it has a 4-stroke engine but it's blowing white smoke. it starts on the first kick and idles perfectly, but it eventually fouls the plug when ridden and i have to clean the electrode. after that, it starts right back up.

the guy i bought it from said that it didn't smoke when it was last ridden, but that it sat for about a year before he started it when i went to look at it. i drained the oil from the crankcase/transmission and it was milky brown. i've changed it two more times since and the color gets better with each change.

what are my chances this thing will quit smoking after it has ran a while? i'm afraid it needs a ring job but i'm grasping for good news. by the way, i bought it for about half of what they are going for because of the smoke and the back brake was shot. if it needs rings i'll still be money ahead.

 

[GTClown]

How did it get the water in the case?
If it sat for a while with water in the case it may have caused problems with the top-end.
That might be why you got it cheap. You would be best off to break it down and check things out.

 

[jmoffett]

is water causing the milky color? they said they also got a little water out of the carburetor, too.

 

[dennybsh]

Water would cause the oil to have a milky color. I'm not familiar with those bikes, but my son had a Honda 80 that was water-cooled several years ago. Is this one air cooled or water cooled?