KLX 250S carburetor problems

[chico]

Hey I have a klx250s and put a fmf pipe and rejeted also opened the air box
The bike works fine at sea level but I recently took a trip to the caribou and it ran like crap.So I went my bike shop in town and they suggested to put on a external air fuel adjuster kit so I can dial in the mixture when I go to higher elevations, seeings how my adjustments are now internal on my carburetor
Has anyone had this done to there bike and if so how did it work for you
Thanks:shock:

 

[Island Hopper]

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Your bike may run better at sea level but I'm guessing that it's jetted a little on the rich side even for 0 elevation....

The fuel mix screw is only effective for idle to maybe 1/8s throttle then your onto the pilot jet until about 1/4 throttle.... The biggest effect comes from the needle jet/jet needle which controls the fuel for the most used RPMs from 1/4 to approx 5/8s throttle... After that the main jet takes over....

You maybe able to clean up your richness by adjusting the jet needle so it sits one clip position lower {move the clip up 1 from pointy end} in the needle jet... If it doesn't have clips it may have a shim you could remove or replace with a thinner one to get it lower...

Having an adjustable low speed fuel screw helps to give you a clean idle provided your pilot jet is close to being the proper size....

 

[chico]

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Thanks for the info island hopper
I will run that info by my mechanic and get his thoughts on that
I don't want to make unnecessary mods if it's not going to fix the problem
Thanks

 

[dirtrider]

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I did the same to my KLX450, air box, pipe...then rejetted going 2 up on the main, 2 up on the pilot, cheaped out by not getting the fuel screw but figured it could be close enough with a guess on 2 turns out...well rode up Vedder to 1000 meters and ran like poop...got a fuel screw from Gnarly and what an inprovment!!! it turns out I only needed 1/2 a turn out. Now the bike starts easy, runs so crisp that on idle I can now just let the clutch out and it will pull and not stall..

The fuel screw has a way bigger effect than I imagined. Not like the air screw carbs where a turn hardly makes a change. On the fuel screw 1/8 makes a diff between a hesitation/bog or rough and surging engine...

 

[chico]

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Hey dirt rider
Thanks for the info I talked to my mechanic about the fuel screw and they told me it will make a difference although they seem to be having problems locating one.I'll tel them about gnarly parts to give them a call see if they might have screw
But in the mean time i'll try adjusting the jets. see what differents that make
Heading up to inks lake area this weekend :clap:so want the bike running good
Cheers dirtrider