Fouling plugs ?

3 replies to this topic
  • edeuce

Posted August 16, 2013 - 04:08 AM


I have 2011 YZ450F and fouling plug bot every 4 rides ? I had an unplugged air sensor thought that was my prob. Guess not ! I have the MXA performance map loaded. Runs great but will foul plug @ first cold start.? Plug really black. Thinking maybe valve seals r leaking some. Wondering if anyone has this happen ???

  • grayracer513

Posted August 16, 2013 - 06:46 AM


It sounds like you may have the incorrect spark plug.  One heat range too cold will do this.


Of course, it could also be weak ignition or a rich condition.

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  • edeuce

Posted August 16, 2013 - 09:07 AM


Stock plug and did same w/ stock map.??

  • grayracer513

Posted August 16, 2013 - 09:45 AM


 A rich condition could be the result of a leaking or otherwise faulty injector, or an incorrect PM signal from the ECU.  Could also be the ignition, as I mentioned. 

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