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Dart 400F

Stumped, PLEASE HELP.....

8 posts in this topic

Background: 1999 YZ 400F 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!!!!

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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.

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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.

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