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Idle won't adjust

3099 Views 4 Replies 3 Participants Last post by  Helmut
I have an 88 fourtrax 300, been fixing last odds and ends on to get to trail riding shape. I will ride for a while with the idle consistent even while not moving, but eventually idle revs higher and won't calm back down to normal idle either in gear or in neutral...I have tried to adjust the idle with the black knob under the seat, as I did on my 90 before, but the adjust knob seems very loose and doesn't seem to be doing any adjusting in either almost seems this possible and how to fix?

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I agree with Shadetree. Take the carb off and clean it good, but you might have two problems. The idle screw might be stripped too. While you have the carb off cleaning it, look inside at the throttle plate and turn the idle screw and see if it opens the throttle plate.
Will I have to take the gas tank off to have room to do this or can I get to it from under the seat in the air-filter box area? Haven't done much to a carb before so might sound like a dumb question.

I would remove the seat and gas tank to get more room. The gas tank only has one bolt at the rear and then it just slides back. Don't for get to turn the gas off and unhook the gas hose. After you get the tank off, I would unbolt the bracket (4 bolts) that the gas tank bolted to, just to have more room. Now, you should be able to get to the carb pretty easy.
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