Stalling problem

4 replies to this topic
  • gardnpa185

Posted November 06, 2006 - 01:47 PM


I have a 2003 YZF450 that usually runs great. I raced a Hare scrambles yesterday and had a hard time keeping it running. I have a GYTR flywheel that helps but for some reason it would backfire and then stall in the slower sections. It was around 45 degrees here yesterday. I am thinking that it was either too lean or the idle too low.

Anyone else experience this problem?



  • kawirider

Posted November 06, 2006 - 02:09 PM


If you have not already, you might want to bump the pilot to a 48 and turn your idle up 1/4 turn when your doing a lot of slow stuff. Make sure you use your fuel screw to fine tune it all.

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  • 642MX

Posted November 06, 2006 - 02:21 PM


A 48 pilot is too big for a 03. They come stock with a 42.

It sounds like it was a little cold outside and running a bit lean. I would try to turn out the fuel screw and see if the popping goes away. If you have to turn the screw out more than 3 turns to make it run right, then you should replace the pilot jet with the next bigger jet (a 45).

Remember, a properly jetted YZF will have some (not a lot) popping on deceleration.

  • scottbob99

Posted November 07, 2006 - 08:07 AM


I rode my 03 this past Sunday (50 deg), I had to adjust the air screw out a little and it ran fine.

  • YZ426F Rider

Posted November 07, 2006 - 08:38 AM


Fine tune your fuel screw and if there is still a problem then try adjusting your idle up a little bit...I'll do that when I'm running a HS on tight trails and it helps quite a bit.

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