help with jetting (please)

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volkoff
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help with jetting (please)

Post by volkoff »

As some of you know I have a 2003 KX220 hybrid. When I bought the KDX it ran decent down the road (85 degrees). I have not been on a 2 stroke in 30 years so not sure how it should run. It had some sort of FMF (I think) silenser and PC platinum 2 pipe. Now that the hybrid is done, the maiden voyage (granted pretty cold 38 degrees) with a FMF Gnarly Woods pipe and a FMF Q series silencer, First thru third gear sputtered quite a bit. 4th thru 6th seemed pretty strong. I am assuming this is some sort of jetting issue, and do not want to mess with it till it warms up outside. I am asking for a little suggestion on where to start to figure this out. I wrote down the current jetts but you might know I can not find it. I will be running Maxima 927 at 32:1, new piston, rings and every bearing and seal in the motor. Check out my hybrid thread, might help.
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Jaguar
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Re: help with jetting (please)

Post by Jaguar »

to lean out the jetting that is in effect before the throttle is fully opened:
turn the idle air screw counter-clockwise and drop the needle

to lean out full throttle jetting:
replace the main jet with one of a lower number.

all this is assuming the air filter is clean and you didn't leave too much oil in it which would restrict air flow and make it run rich
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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bufftester
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Re: help with jetting (please)

Post by bufftester »

Run through the jetting guide, don't skip any steps, starting with your current jetting. The guide will walk you through the adjustments you need to make to get that bike humming. Temp will definitely make a difference so I'd wait until it warms up a bit, or plan on revisiting the guide later in the season
Bitteeinit
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Re: help with jetting (please)

Post by Bitteeinit »

I've seen that guide a few places, butbi wish it included pictures for the total two-stroke noobs. I've also yet to see an excellent YouTube video on the matter, which is somewhat surprising.
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volkoff
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Re: help with jetting (please)

Post by volkoff »

so, pulled the carb and I have 145 pilot and a 45 main. This KX hybrid has all new top end and every seal and bearing in the motor, new air filter, new FMF quiet core pipe (KX250), FMF woods header, 93 octane with Maxima 927 at 32:1, needle clip moved to top. 1st and 2nd gear have a half to open throttle sputter, 3-6 all range is freakin awesome. I live about 1800' above sea level and 50-95 degree temps. These issues are on 65 degree days. 1st and 2nd are great as long as I am crawling through the woods. Looking for your thoughts
Silverfox
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help with jetting (please)

Post by Silverfox »

I've re-jetted my 220 and the 45 pilot was way too rich went to 42 still too rich. Now I'm at a 40 possibly 38 and is spot on. The main was 145 and am down to 140. I have boyesen reeds though which requires slightly leaner jetting and am running 40:1 mix.
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