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whats the problem????

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Ive had my 06' 250f for about 10 months now. I jetted it when I got it and its ran super good until about a month ago. Now when the bike gets really warmed up its starts running like crap on the low end, popping and sounding really dirty. But if I get the rpm's up it runs like rapped ape. I thought I got some dirty gas so I cleaned the tank and the carb out. No dirt and still runs like crap. I also changed the plug, nothin.

Need your help. Thanks.

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yep check the valves. that or you may need to jet it again for different weather, or whatnot. but since its only bottom end you should only need to change one jet. maybe even the fuel screw??

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This last week my 06' started popping alot on idle and backfiring alot when I let offf of it. Took it to my dealer and they rejeted the carb.

Pilot Jet #45

Leak Jet #45

Main Jet #172

I think they got these specs off of team green manual, but it made my bike into a total differant machine, it's 30% more then I had before.

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I checked the valves a couple of weeks ago and they were in spec. A freind of mine also has an 06' KX250F and our bikes are jetted the same, his runs fine. I'm going to check the TPS tonight. It seems like its an electrical problem. Has anybody ever had a problem with the ignition?

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I would cheack the air boots. Sounds like you may have an air leak. also throughly clean the jets and accellerator pump. your choke maybe sticking also.

you problem doesn't sound like an ellectrical problem mainly because it wouldn't do it just in the low end.

If you still cannot figure out the problem then since your friend has an identical bike. swap the carbs see if that fixes yours and causes his to do the same. If so then its carb related if not well duh not the carb..

I would look into the valves after that then possibly head gasket.

change spark plug

theres me .02

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sounds like you are lean down low on the pilot. I would pull the carb apart and use HIGH pressure air through it. I use about 140psi from my air compressor to blow out the pilot jet. Carb cleaner won't get all the junk out.

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did your fuel scew fall out? this happened to me. It still ran fine at higher rpm's even with no fuel screw in it.

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I have an aftermarket screw made by Zip-Ty Racing, Its got a knurled knob on the end for easy adjustment. I tried a bunch of different settings and it hase'nt made it run better. I think I'm gonna take the carb off again and make sure the jets are clean. I also but a fuel filter to go inline, just to make sure no junk gets through. I'll let you know when I get it figured out.

Thanks for all of the input...

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I had a zip-ty fuel screw. The threds didn't seem to be a perfect match, it was hard to turn. I tossed it in to the tool box and put the stock one back in. Then it fell out and i lost it.

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