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06 kx250f throttle concern

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so i just bought my self a 06 kx250f and its my first 4-stroke. it runs great and everything but one thing that seems weird to me is when i rev it up then let go the throttle goes right back to place but the rpms only drop a little bit then a moment later they drop all the way back to idle. is this anything to worry about? thanks...

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its kinda weird.. ill let off the throttle and it does die down quite a bit actually, it sounds like it did all the way but then it drops just a bit more..

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Have you had the carb off? Was there much wear on the slide? I have heard that when a flat slide carb gets wear on the slide it can cause problems like you have described. Hopefully, White Stallion, D-K or Pr1malR8gw will see this. They seem to very knowledgeable.

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sounds like a hanging idle..i suggest going richer on the pilot circuit..try turning the fuel screw out..if its more than 3 turns go up on the pilot jet if thats not the issue. try turning the idle screw down

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alright ill try that.. could the hot start lever have anything to do with it? when i pull it in it doesnt make it any easier to kick.

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Racer24's suggestion for a true hanging Idle is correct.

If you manually return the throttle does it still hang? If not I would check the adjustment on the return cable and lube both cables.

The Hot start has nothing to do with ease of kicking.It adds a xtra shot of air to aid in starting when the bike is extremely hot. If it is stuck open it will cause the bike to run lean and run like crap.

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make sure that there is no air leak and the clamps on the rubber air boot is on tight or if the hotstart plunger is seized and stuck open...hanging idle usually means its lean..has this always been a problem or did this just start happening

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i just bought the bike so i havnt even had a chance to ride it on dirt yet. i tried turning the feul screw out and it seemed like it made it worse..

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hmm have you tried setting the idle screw...the stock jets usually work through a wide range or elevation/temp unless the elevation is high above sea level. the pilot jet should be either a 40 or a 42...a hanging idle is usually a lean issue..

try Adjusting the idle until it is too fast with the idle screw. Then adjust it back down until it sounds just a little high or around 1900 rpms if u have a tachometer...then turn the fuel screw out usind 1/4 increments and see where the idle feels smooth and rolling on the throttle sounds good..should be more than 3/4 turns and no more than 2 turns..any more you need a bigger pilot jet..i suggest taking the carb out and cleaning through the jets

and figuring out what jets you are using and clip position. and if you can get an owners manual and try resetting the float level..the float level will through off the jetting even if it was spot on...

HERE IS HOW TO DO IT..I USE METHOD 1 http://justkdx.dirtrider.net/floatlevel.html

ALSO how does the bike run on the track..does it backfire when you let off and slow down for turns

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thanks man ill try that.. it hasnt even seen the dirt yet.i just got it last week.but riding it on the drive way i did notice that it did back fire a couple times. i thought that was just a 4-stroke thing..

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if you bought it used, the previous owner might have had the jetting changed..but the backfiring is usually a lean issue ..if its backfiring on decel its usually the pilot circuit which could be fixed either changing the jet size or turning the fuel screw out...i suggest getting an aftermarket fuel screw to make easy "on the go" changes...my bike did that and i threw in a 42 pilot and have the fuel screw at 2....i also lowerd the clip position so i basically raised the needle to let more fuel through

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the guy i bought it from did put in a after market fuel screw but stock pipe so i dought he re jetted it. does the fuel adjuster only go 1 time around from 1 to 4? its at 3 now.

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if your talking about the numbers that are on the fuel screw then no..a full rotation is one..not from the number to the next

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okay.. i think i figured out the fuel screw. so you can keep loosening it till it falls out. right? the guy had it pretty much as tight as it would go. is it suposed to be able to wiggle around a little the looser it gets?

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okay so i turned the fuel screw right as far as it would go then i started it and gradually turned it left till i got to about 3 or 4 turns out and it sounds much better. the throttles way more snapy and it goes pretty much strait down to idle. i havnt looked at the jets or pin yet should i bother?

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If you are 3-4 turns out you should step up the pilot jet.

I'm willing to bet it is a stock 40 pilot and requires a 42 pilot.

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