Slight smoke


8 replies to this topic
  • bhsballer76

Posted July 24, 2009 - 07:02 PM

#1

After riding with my buddy for a few hours the other day i noticed that when he revved it real hard there would be a slight bit of smoke coming out of his exhaust. His bike is a strong running 2005 yz450f. We took a look at it closer before we loaded it up to head home. It only happens on a good quick rev.Its not blue smoke so i dont think its burning oil. The smoke has more of a white/gray tint to it.. Anyone have any ideas?? Thanks to all.

  • crf250r_motorhead

Posted July 24, 2009 - 07:28 PM

#2

could be getting a little oil past the rings or valve seals..

  • bhsballer76

Posted July 25, 2009 - 06:14 AM

#3

could be getting a little oil past the rings or valve seals..


yea, that was my fist thought too. The thing is its a very light smoke and it is not constant at all. It only happens on hard revs. I guess it could be though. Any possibility its a jetting issue?

  • crf250r_motorhead

Posted July 25, 2009 - 06:48 AM

#4

not with white smoke. could be if it was black smoke.

if it does it when its cold and your crack on the throttle thats fine IMO.

it shouldnt be doing it when warm though.

and even if it does slightly i wouldnt worry about it. unless the smoke hovers like a 2t.

id say your good!

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  • bhsballer76

Posted July 25, 2009 - 03:22 PM

#5

not with white smoke. could be if it was black smoke.

if it does it when its cold and your crack on the throttle thats fine IMO.

it shouldnt be doing it when warm though.

and even if it does slightly i wouldnt worry about it. unless the smoke hovers like a 2t.

id say your good!



alright, what if it was black smoke. Could that be a jetting issue??

  • TIG88

Posted July 25, 2009 - 05:43 PM

#6

alright, what if it was black smoke. Could that be a jetting issue??


Black smoke is indicative of an overly rich condition. I'm sure it would run a little rough if it was blowing black smoke.

The symptoms you have described are the first indication that a little bit of oil is getting past the rings. Probably time for a top end.

From my experience most of the time:

High revs-Rings starting to get weak
Startup and/or deceleration-Valve seals

  • bhsballer76

Posted July 26, 2009 - 05:01 PM

#7

Black smoke is indicative of an overly rich condition. I'm sure it would run a little rough if it was blowing black smoke.

The symptoms you have described are the first indication that a little bit of oil is getting past the rings. Probably time for a top end.

From my experience most of the time:

High revs-Rings starting to get weak
Startup and/or deceleration-Valve seals


hmm... ok. thanks alot. Anyway to do a compression test on these motors ?? I know they are auto decomp so i am not sure. Thanks.

  • TIG88

Posted July 26, 2009 - 06:25 PM

#8

hmm... ok. thanks alot. Anyway to do a compression test on these motors ?? I know they are auto decomp so i am not sure. Thanks.


You can do it, but its pretty much useless. A Leak Down Test will show you where its leaking, and how bad.

  • bhsballer76

Posted July 27, 2009 - 09:12 AM

#9

You can do it, but its pretty much useless. A Leak Down Test will show you where its leaking, and how bad.



alright. Thanks.





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