Engine Sputter on 03 YZ450F

8 replies to this topic
  • 2weelz

Posted October 05, 2006 - 04:51 PM


BTW, this is a street legal supermoto bike.

I am hoping someone can shed some light on my sputter problem. The engine always starts right up. It always runs great when you're applying throttle. Problem: when at a cruising speed and approx 3/8 throttle or less, the engine sputters every second or two. As soon as the throttle is applied, it runs strong with no sputters.

I just bought the bike today so I don't know any of it's history. It has a full exhaust and was told the carb has factory jets...I can't verify that. This bike came from Arkansas so I'd imagine it needs some jetting changes for the different altitude. What do you think?

  • Way Fast Whitey

Posted October 05, 2006 - 05:10 PM


does it do this in a certain gear by any chance?

you could just clean the carb really good and try it again. if it only does it in a certain gear(or two maybe) you might have tranny trouble.

  • grayracer513

Posted October 05, 2006 - 08:17 PM


At that low of a throttle opening, the pilot still has a significant influence. You might try fudging the fuel screw out (or in) a half turn to see what happens. Could be slightly lean at that point. A lean misfire should be kind of irregular. Rich is usually a more regular sounding stutter.

  • 2weelz

Posted October 05, 2006 - 08:17 PM


I think it does it in all gears. I'm pretty sure it's an engine miss.

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  • 2weelz

Posted October 05, 2006 - 08:42 PM


I'm not too knowledgable about carbs but the previous owner said he messed with the fuel screw (on the bottom, front) with no luck. What about a jet kit? It did come from Arkansas.

  • sthedreem

Posted October 06, 2006 - 05:49 AM


2 weelz
Here is the thread from when I was checking on this:


  • GreenKLX

Posted October 06, 2006 - 09:49 AM


The easy fix!

  • 2weelz

Posted October 06, 2006 - 05:05 PM


I can install this jet kit and problem solved?

  • 2weelz

Posted October 09, 2006 - 10:46 PM



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