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mpowers

98 yz400 idle problem

6 posts in this topic

clean carb acc pump clean everything set right, idle screw is at the max to get it to idle,fuel screw set a little over 1.5 turns. btw I installed a zip ty fuel screw and tried to start...no go. took it apart and the fuel screw had broken off in the carb. not fun trying to get it out but its out. I sent it back to zip ty and haven't heard back yet.

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clean carb acc pump clean everything set right, idle screw is at the max to get it to idle,fuel screw set a little over 1.5 turns. btw I installed a zip ty fuel screw and tried to start...no go. took it apart and the fuel screw had broken off in the carb. not fun trying to get it out but its out. I sent it back to zip ty and haven't heard back yet.

Ok, so what exactly are you asking???

:thumbsup:

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Is this when warmed or while cold? Does it idle with the choke out? then dies when the choke is pushed in? How does it run otherwise? I would check two things. The first obvious is the fuel screw. I would also check the hot start valve to make sure it is sealed when not used. These little gems corrode easily from cleaning. Two ways to check the valve is one, plug the end of the hose leading away from the valve or remove the vlave assembly and blow into it. If air can pass through by blowing into it then you have a leak.

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it will idle both warm and cold, it runs fine but it just seems wrong to have the idle adjusted all the way "in". I did find that the hot start plunger rod is bent...not sure about the thing leaking I will check it. Got my new zipty screw today and will get it in and try to get it dead on......thanks

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My 98' YZ400 is having the same problem, except mine will not idle at all. My idle is all the way in as well. I'm getting ready to check the hot start. I've tried my fuel screw in various positions with little or no affect. When I ride, it is popping on decel. I have new gaskets for the exhaust on order. If you figure out your problem please send me your info. It might help me too. Thanks.

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