1991 KDX 200 Jetting Advice

[zzmongo]

My '91 KDX 200 is really a great bike except its running too rich at the moment. Measured cylinder pressure, about 140 psi, carb is clean, new filter. Bike has a FMF Gnarly pipe with the approved spark arrestor, Boyeson power reeds and an opened up airbox. Anyone have jetting advice? How do I go about cleaning the power valve? Other than the rich condition (smoking alot) the bike is wonderful. In fact, I'm looking for another for my 13 year old son so he'll stay off mine. Thanks!!

 

[Rockey5000]

Is the rich condition throughout the throttle range, or at 1/4 through 3/4, Idle through WOT, 1/8 to 1/4, etc. Some smoking is normal with 2-Strokes, but excessive is rich jetting. To lean up the Pilot Circuit(idle-1/8 throttle) Turn OUT the air screw. If this does not fix the problem, so to a smaller pilot jet. To lean out the Needle Circuit (1/8-3/4 throttle), raise the clip position until you find an optimum setting. To lean out the Main Jet (3/4 to WOT), simply go to a smaller size main jet. I reccomend doing a WOT Plug chop to make sure the main isn't too lean, and listen for a boooooooooowah sound in 1/8 to 3/4 throttle, if you hear it the clip is too high so try lowering it. Adjust the air screw by turning it all the way in and backing it out until RPM peaks(don't turn it out too far though, the revs will stay up but the exhaust will sound dull and lumpy). I hope this helps, if you have any questions, just send me a PM, I'd be glad to help.

 

[XE326]

i have a 91 KDX200 prociruit pipe and silencer, power reeds, modified airbox cover and i'm running 48 pilot and a 152 main and a 1173 needle in the mid clip position, works good for me, mine smokes a bit when you first start it up till it's warm