Stumped, PLEASE HELP.....

7 replies to this topic
  • Dart 400F

Posted June 07, 2007 - 12:08 PM


Background: [COLOR="Blue"]1999 YZ 400F [/COLOR]Ran bike last Sat. (ran great) for 3hrs. Started raining, bike sat until it stopped. When it stopped raining I got the bright Idea to go play in the mud. 5 mins into the ride, the bike starts studdering and lerching and having some serious bogging issues. Got so bad that the bike wouldn't even take off from a stand still (would start though very easily). Got it back to camp and It sat for the remainder of the weekend.

What I have eliminated I think: Drained about half a gallon of fuel out of the tank thinking water somehow got into the tank. ran it up and down my road for a couple laps and a serious bog issue is still very apparent. I'm thinking water in fuel not the issue?

Problems I am considering: Clogged jet/ needle? Bad throttle pos. sensor (if it has one, no Idea)? CDI unit?

Please help with any other problems you all might think may help me solve this grand mystery. I feel the bike had plenty of time to dry out before the run through my neighborhood 2 days ago. Could it be just an electrical connection some where?

Help Please!!!!

  • grayracer513

Posted June 07, 2007 - 12:15 PM


Just because water isn't in the tank doesn't mean it's not in the carb. Drain the float bowl, and put 4 oz of ethyl (preferably) or isopropyl alcohol in your tank to absorb any left overs.

  • Dart 400F

Posted June 08, 2007 - 12:38 PM


I never thought of that. I'll be doin that this weekend. Thanks for the tip!

  • TeamPrecisionIT

Posted June 08, 2007 - 12:41 PM


Also check the neck from the airbox to the carb and get some compressed air through there.


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  • CaptainKnobby

Posted June 08, 2007 - 08:39 PM


check your plug wire and make sure your pet cock isnt being restricted by some foreign debri.

  • Dart 400F

Posted June 09, 2007 - 02:53 PM


All great suggestions. Thank you all.

  • Dart 400F

Posted June 13, 2007 - 01:59 PM


Finally got to tearing into my bike tonight and what did I find........ My plug wire somehow became dislodged from it's intended position. I guess I was freaking over nothing. Thank you for all the great ideas.

  • BergArabia

Posted June 14, 2007 - 04:39 PM


Glad it worked out well and painlessly.. :thumbsup:

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