400 spark plug question

3 replies to this topic
  • bubbaisthebest

Posted January 24, 2009 - 12:55 PM


I have fouled many plugs (cr9e) in my bike over the past few months. Would running a hotter spark plug (cr8e) get rid of the fouling? My last resort is to change the jetting. Thanks for any info.

  • Michael Cahill

Posted January 24, 2009 - 06:36 PM


I had this same problem in my bike.
I ride alot of trails, so i figured since im not really ever getting into the top end much, the engine never really gets a chance to burn nice and hot to keep the plug from fouling.

so i leaned out the needle jet by moving the lil circlip up one position.
this seemed to have fixed the problem, because i have yet to foul a plug, and when i pull it out to check it, its always nice and tan looking :banana:

so basicly,
plug fouling= over-rich condition.

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  • grayracer513

Posted January 24, 2009 - 10:04 PM


You are running too cold a plug. The bike calls for a CR8E.

  • bubbaisthebest

Posted January 25, 2009 - 06:27 AM


Thanks for the replies, you answered my question

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