Jetting question

[Sandman 2.0]

I have a 2001 KDX200 which I've rejetted but it still seems to be running a tad rich. From idle to about 1/8 throttle, not much smoke. Above that, I'm getting smoke and still some splooge. I'm at about 800' above sea level, stock pipe and silencer. Air box lid is cut leaving just enough to hold the ignitor box. Main jet is 155, pilot 45 and needle 2nd position from the top. Ready racing air filter. Now it runs fine, idles ok and rips through the power band but does smoke a bit. The plug is still showing a slightly rich condition. I'm wondering where to go from here and if anyone has found a good combination pilot/main whit a 200 like mine with stock pipe and silencer. I'm thinking a step down to 152 main/42 pilot. Also, I may get a FMF Gnarly and silencer this winter. Would that have much effect? Any help would be appreciated!

 

[_JOE_]

Leak down test. Could be a crank seal.

 

[Sandman 2.0]

Thanks but no, not a crank seal. Engine has only about 4 hrs total on it. Uses no trans oil. Tranny oil has a very distinct smell to it when burning.

 

[John Harris]

My experience has been to go to 42 pilot and leave the 155 main. You have to be very careful not to get the main too lean for that is where engines (two stroke) seize. Mine even ran great on a 40 pilot when weather was hot, but was too lean when weather was cold. You may still get a little smoke. Hard to explain, but stock muffler has a "reserve" of oil, so changes in running and jetting have a lag showing up in the smoke department. Nearly every two stroke will smoke a little sometimes under some conditions! Enjoy John

 

[Sandman 2.0]

Thanks John

I was wondering about that also. I've seen 2 strokes where the packing was oil soaked smoke no matter what you did to the jetting. I know the stock muffler doesn't have packing per se but I guess it's possible the oil builds up in the knooks and crannies. I appreciate your input.

 

[blackduc98]

I spent a long time messing around with jets and needles. I've gone through many combinations recommended by other kdx'ers, but still the bike had rich symptoms in certain throttle ranges. For example, my pilot air screw didn't seem to work as advertised. I finally said "screw the recommended jet sizes" and went back to basic principles of jetting, i.e. plug reading and ride-and-feel. I am now running a 38 pilot at sea level with temps around 60F, and it finally feels right. The air screw is now effective at about 1.5 turns like it is supposed to be, the plug looks better (but still a little rich) and the bike runs cleaner. My main is #152, my needle is stock (1174) with clip in #2 position. I've got an FMF rev pipe and Vforce-2 reeds. And my airbox lid is intact, with only the snorkel removed. So what does all this tell you? Not a damn thing, except that you shouldn't be afraid to go beyond what others are recommending for jet sizes, as long as you follow basic principles of jetting.

Oh yeah, another little thing I discovered along the way is that there might be a huge variation between individual carbs. It turned out that my carb had a gap between the jet block and the carb body (think air leak). And even though there is a rubber gasket in there, it didn't seal the gap. Let's just say I'm not very impressed with Keihin's manufacturing tolerances. Check out the photo: a feeler gauge easily slips into that gap! That ain't right! And it will certainly make a difference in the pilot and transition circuits. BTW, I took care of that gap with a couple of o-rings.

 

[Sandman 2.0]

Blacduc thanks

That is pretty interesting. I'm going to install a 42 pilot and 152 main this weekend and check the plug. I'll check that gap on my caburetor at the same time. My bike actually runs pretty good but to get a decent off throttle response and consistent idle, I'm about 21/2-3 (Indicating I need at least a leaner pilot) turns out on the air screw and I'm getting quite a bit of smoke/splooge still. When climbing a hill, I leave a bit of a smoke trail behind me. I think the 42/152 combination may do it for me. Not to get off subject blacduc but I see you have a WR250 listed also....how does it compare to the KDX? I always thought they looked kind of trick but I think it would seem a bit heavy compared to the the Kawasaki.

 

[blackduc98]

WR is heavier. Suspension is very different. Power is very different. Starting it is a PITA, whereas KDX starts in 1 or 2 kicks every time. KDX maintenance is definitely simpler.