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kx250 jetting

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can anyone point me in the direction of a kx250 jetting database (searched and cant find)

or give me some info on jetting for my altitude and heat and humidity

 

i am in australia and ride trails/ enduro

 

so far my jetting is as below:

 

all riding at sea level

fuel mixture 40:1

pilot jet 42: (plug showed dark brown colour

air screw: winter  (15 - 25 degrees celsius  30% humidity )1.5 turns  / summer 1.75 turns 35-40 degrees celsius / 95 fahrenheit ?

80-90% humidity

needle: 3rd clip (standard as far as i know)

main jet : 158 (plug chop showed light brown/ tan colour)

does not seem to slutter on to needle

no spooge and just a little whisper of smoke when revved

 

mods are fmf gnarly pipe and v force 3 reeds

 

am i heading in the right direction ?

 

thanks in advance guys

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What year is your KX?  In my 2003 these settings would be really lean at that elevation, but it seems to be working well for you.

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I would probably try dropping the needle one position.  I am running the same main and a smaller pilot in mine but I ride at about 5000 feet ASL.  A 155 main would be just right for me but mine snapped off last time I used it.

 

I'd say you're pretty close.

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I know you can buy the jetting chart from JD Jets. Off the top of my head I want to say it is $20 and he sends you all his info in an excel sheet

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Dyldog it is a 2000 model

Do you think the main is to lean ?

Is it costing me power ?

Edited by kxrob

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If the main was lean you would likely see that in the plug color but it sounds like you have a good color on yours.

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will find pic of plug

Edited by kxrob

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Thanks shrubitup :

 

everything looks similar to what i got except if i ran a 50 pilot i'd be fouling plugs all the time

i think the pro circuit settings would be okay for 32:1 (leaner on fuel) and for motocross where your not on the pilot circuit a lot

 

i think i pretty much got it dialed in now , just interrested what ours in similar conditions were running

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What's the history of the bike?  Did you just buy it or was it stock and you put the pipe on?  You generally go leaner with the Gnarly pipe. 

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Had bike for over a year and jetted to specs in 1st post

Just seeing what other people run in similar conditions

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Bumping post ,

Im thinking about making the switch to full synthetic pre mix and going to 50:1

Most of my riding is from idle to 1/2 throttle in third gear

I was going to rejet by going to a 42 pilot (adjusting air screw to suit ) and dropping needle down by raising clip to 2nd position ( clip in 3rd position at the moment)

What is a good replacement needle for the stock one (n3we ? Is in it now)

Sorry for a long post but I'm on a quest to have it run as clean as possible at idle and up to over 1/2 throttle

Goal is to have minimum smoke and a clean running pipe

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This is my pipe after today's ride

It was a hot day (35degrees Celsius/95 Fahrenheit)

And at sea level

image.jpeg

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admirable looking pipe there. I wouldn't try to lean it out based on that. Many have the drool running down whole pipe and dripping on swingarm. 

 

Pro Circuit says N3WF. I used their recommended settings for my 99 other the pilot jet which is a 48 vice the 45 they say. May switch back to 45 in the summer but it Works great! 

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pipe is pretty wet with oil inside .

 

when it gets revved  past 1/8 throttle it is a bit oily and takes a bit to clear out

 

im going to repack silencer soon and clean out the expansion chamber as well

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