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Hanging idle 05 250f

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We are on our third 250f 03, 04 and now an 05 and are having a small idle issue. after a moto the bike likes to idle at a faster speedthan what was set before.

If you blip the throttle a few times it will slow down, But its almost like it has a dashpot like a car with a carb and auto trans. to keep the moto from stalling.

It has been cold with really dense wet air latley and all the four stroke are running lean in these conditions.

Our bike seems to be running a little rich. Stock jetting, sea level and 28-50 degries

I'm giong to try a 180 main and put the Zipty fuel screw back in from our 04 and see how it goes this weekend.

Cables are clean and carb slide works great.

Any input?

Thanks,

Eric

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Mine does it but it seams that when I readjust it when the motor is up to temperature then the idle will stay where I put it. If I adjust it low when it is cold it will get higher the hotter it gets. I like it a little high to help with stalling.

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Hanging idle is a sign of a lean idle mixture. Check the intake tract for leaks by squirting some staring fluid at all the joints (air boot, carb clamps, etc.) while the bike is idling. If it speeds up, you've found the leak.

If you don't have any leaks, then open the fuel screw in 1/4 turn increments until the hanging idle stops. Do this adjustment with the engine fully warmed up. If you get more than 3 turns open from fully seated, then you may have to go up one step on the pilot jet.

The winter weather and denser air causes your mixture to lean out. I wouldn't richen up my main jet unless it was missing at the top end, and certainly not to cure a hanging idle. You probably know all this stuff, but just trying to cover all the bases.

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I've also been having an issue with a hanging idle on my 01 yz250f. I recently added a zipty adjustable fuel screw and it made the process of solving the problem alot easier. My fuel screw was set a 1 3/4 turns out, it's at just about 2 turns out now and it seems to be running ok. The hanging idle is gone but I notice it will do it if the engine is not fully warmed. Once it warms up it goes away. In the summer I don't have a problem with it at all with the fuel screw at 1 3/4 turns out do to the temperature. Let the engine warm comletely, adjust your fuel screw, as said if the problem isnt going away before 2 full turns out then you either need a bigger pilot jet or you may have an air leak.

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