Blue smoke start up after sitting hot?

8 replies to this topic
  • Thumper_426

Posted May 20, 2007 - 05:30 PM


I rode about 100 miles the past two days and rode a few trails that were not by choice slow, bike felt hot at times and I would open it up whenever I had the chance and tread water as well when I could slowly to keep bike cooler. But everytime I stared my bike, a puff of blue smoke would come out, can't say I remember a 4 stroke doing that. No problems w/the bike so far, 416 miles on it now. I change the oil every 3rd or 4th ride also. I'm not panicing, just wanting to know if its normal since I was running hot a few times not by choice. Temp outside was about 65*
Thanks for any input. :)

'06 WR450F free mods still..............

  • responding

Posted May 20, 2007 - 06:57 PM


I can't say for sure, but I have an 02 wr426, and have never seen a puff of smoke in the time I've owned it. I know I've gotten it pretty warm at times, (the kind of warm where you can hear the radiators cracklin'), but that has never caused a problem. I do alot of extremely slow, technical riding where sometimes I don't get out of first gear for 30 min or more. Blue smoke generally signifies oil burning, and if it does it immediately after start up, then goes away, that usually means valve seals are worn out. I'm going off my automotive experiance, and do not know if it's applicable to these bikes. Also, usually if it is valve seals, it will do it the worst when you first start it cold after not having ridden for awhile. Hope this was some help. Best of luck!

  • responding

Posted May 20, 2007 - 07:01 PM


By the way, I'm usually riding in 90 - 110 degree heat, so I suspect in 65* weather, you would not get it hot enough to do any damage. If it is valve seals, they are a cheap and easy fix I think.

  • dl19

Posted May 20, 2007 - 08:52 PM


Sounds like valve guide problem leaking oil by. Maybe a warped ring, but something is letting oil by.

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  • Linc007

Posted May 21, 2007 - 05:14 AM


If you can, take a look in the intake tract,remove the carb and boot,get a flash light and peer into the port and look very carefully at the valve stems and at the valve heads,if the seals are bad enough,you can sometimes see the oil on the valves.Also check the exhaust side.Another way to check is to have a buddy follow you down a hill(preferably on pavement,,,no dust)rev the engine high,cut the throttle and then roll the throttle back on ,if a chuff of blue smoke comes out then,generally that means the seals are getting weak.


  • dominator426

Posted May 21, 2007 - 10:38 AM


What kind and grade of oil are you using, Thumper_426?

  • Thumper_426

Posted May 21, 2007 - 03:26 PM


I've been using Vavaline 20 50 w. I'm going to buy some Yamaha lube or eql. oil vs what I have been using from now on also. Thanks for the info. guys. I won't have time this week to do any work on my bike, Dental surgery. But next week I should be able to check it out closer. I've thought about switching over to Royal Purple also anyone use that in they're 4 stroke?
Thanks again, Mark

  • farkawi

Posted May 21, 2007 - 05:14 PM


Where there's smoke there's oil in the combustion chamber. There are only three ways for this to happen. 1. Down the valve guide. 2. Up past the rings. 3. In thru the carb/intake tract. The third is rare and usually only occurs when the airbox gets full of oil pumped out by the blow by tube. A leak down test will tell the horrible truth.

Royal Purple is good stuff. Been using it in my '05 since the 2nd oil change. I'll likely buy another case when this one is gone.

  • Thumper_426

Posted May 23, 2007 - 11:00 AM


I'm home now, can't do much of anything since Dental surgery. But my friends bought me some Royal Purple and new oil filter. I was told bike was running hot on trail and it should be fine. Bought me some ICE also for radiator and Friends test rode it a few times while I was out of commission and said its ok. Cleaned carb out and air box again. I'm very meticulous with my bike. I don't leave it dirty over night. I clean it as if I just bought it off the show room floor everytime. Yeah, ride for 4 or 5 hours a day, and clean it for 2 after words. Hope to up and riding again soon. Pretty wobbly myself right now, but just being able to see my bike in the garage makes me feel better.
Thanks for everyones info.
Mark :) :ride:


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