White Smoke ? yz450f 03

5 replies to this topic
  • motocopbyday

Posted May 05, 2008 - 05:36 AM


I searched site but need more info. Installed fly wheel weight, changed oil, now i have white smoke after starting (like a two stroke). The bike was perfect before I made changes (no smoke). The bike was like new when i bought it from someone with too many hobbies. It couldn't have enough hrs on it to need rings. It had original everything, tires still had nubs. My concern is that it sat in his garage without use. Rings? valve seals? where do I start?

  • grayracer513

Posted May 05, 2008 - 08:30 AM


The first question is whether you did the oil change correctly, which is to ask whether you drained both the crankcase and the frame/oil tank. If it sat that long without being started, there may well have been no oil in the frame, but if you fail to drain the frame during an oil change, the result is an overfill condition.

That, however usually ends up as a situation in which the smoking, if it happens, continues as long as the bike runs, and even gets worse when it gets hotter. It's also usually accompanied by excess breather oil exhaust.

White ("blue") smoke on start up that lasts for just a minute or few, then stops, is usually a sign of leaking valve guide seals. Oil drools down the intake stems while the bike sits after running, and there is enough of it on the next start up to show as smoke. This can be corrected without removing the head, by not with the tooling most people, or even many shops have, and replacing the seals usually means the head must come off.

  • motocopbyday

Posted May 05, 2008 - 09:29 AM


Thank you for your response. This was actually the 2nd time I changed the oil. I had to drain it to install weight. I drained frame both times, oil level looked good. I guess I will have to take it in. I am just shocked that it happened so suddenly and right after flywheel weight was put in. My two strokes always gave a little warning. Is there any chance that If I didn't drain all of the old oil out it wouldn't register as overfilled on dip stick when bike is hot?

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  • grayracer513

Posted May 05, 2008 - 11:17 AM


Is there any chance that If I didn't drain all of the old oil out it wouldn't register as overfilled on dip stick when bike is hot?

Not after it's warmed up, no.

  • motocopbyday

Posted May 05, 2008 - 06:04 PM


I guess i will be taking it to the dealer. Thanks

  • BigBore364

Posted May 05, 2008 - 06:46 PM


Heck Id just filler up with oil and run it or just sellit and get a KTM

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