Fouled Plug

5 replies to this topic
  • stathy1

Posted January 02, 2006 - 07:43 PM


I just bought my son a 2005 yz85 and he is just learning to ride the new
bike and is not riding it too hard and is having a problem of fouling the plug.
What can anybody suggest i do to stop this from hapening.Should i turn in the pilot air screw adustment to lean it out a little? Or any other suggestions.
Other than that the bike runs great.I am also mixing the fuel at 36 to 1

  • BigIvyI

Posted January 02, 2006 - 07:50 PM


try dropping the main jet one size at a time.

  • stathy1

Posted January 02, 2006 - 07:55 PM


you don't think i sould change the pilot air screw?

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  • jct404

Posted January 02, 2006 - 08:01 PM


My boy's 65 was similar and I dropped the needle one notch, you may even go a size smaller on the idle jet too. If he isn't opening it up you need to cut back on the fuel. 0 to half throttle is mainly your air fuel screw, slow idle jet and your needle position in the main jet in that sequence. Dropping the needle and adjusting the air/fuel screw cost $0.00.

  • stathy1

Posted January 02, 2006 - 08:09 PM


I'm not quite sure how to drop the needle at this time so do you think ajusting the pilot air screw alone will help?

  • jct404

Posted January 02, 2006 - 08:33 PM


Not really, The owners manual should have a step by step description on how to do it. It not too bad especially on the smaller bikes.

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