Where do you have your air screw set? These work best with the screw set about 2.5 to 3 turns out. Make sure your float height is set correctly because that will change the overall jetting.
I would increase the pilot and main jet sizes. The designer of the STIC, George Boswell, told me that many KTM rider have are having good luck using larger main jets in the 195 to 200 range. I was told that the main jet overlap into the pilot jet throttle range (more than the stock Keihin) because it reduces the required draw and makes it easier for the carb to pull fuel at lower rpms. George said while it sounds odd, they run fine on top without being overly rich.
Our 125 had a similar problem being lean 1/4 to 1/3 throttle range. It was using the NEDJ needle (provided with the kit) raised to the top and I was able to correct the lean spot with a larger main jet and pilot jet. Ultimately I will probably use the NEDG needle in the 125 like I am using in my 327.
|