Maybe your bike REALLY wants to be a 2-stroke bike and it's in the process of transformation. . . . . sorry, I just couldn't resist!

 

haha good one... could be part kdx too, you never know with those second hand bikes it could be a mixed breed lol...

 

Well, there's no doubt that it's oil burning at start-up. I would just take the plunge and replace the valve seals.

 

a friend had the same exact problem on his 1996 klx 650. We thought it was the valve seals too so we replaced those but the bike still smoked. Turns out it was the piston rings. We were going to replace the piston but it looked fine so we just did the rings. The bike hasn't smoked since. It could be the valve seals but if I were giving advice I'd suggest doing both at the same time so that you don't end up going back in there again if it's not the seals.

 

+1 on that, better safe than sorry. It's not too fun tearing it down twice if you can take care of it the first time.

 

i was thinking about that yesterday and i think if i do tear it down i am going to do both of it... it could even be a combination of both... but now that its warming up out side the bike dosnt do it half as bad only if you are revving it before it warms up but i start it tith the choke turn the choke off and w8 a min or 2 and its fine... but the rings and valve seals are on my to do list next winter if i dont have it done before then...