New member here, I have an 02 YZ426 that will not run smooth below 1/4 throttle. I cleaned the carb thoroughly and it was the same. Then I assumed it was lean and installed a 45 pilot. Still the same. Installed a new plug. Still the same but will run. Old plug covered in black soot. I went back to the 42, no change. So I checked the valves and cam timing. All the while I have the thumb pilot screw and am able to make adjustments. It runs awesome anywhere above 1/4 throttle. I idled it down the street in the worst position and then pulled the plug. It is covered in black soot. Now I have a 40 pilot and it has not changed. It doesn't seem to be affected by the turns on the pilot screw either. Ugh! Sanded the paint off the frame where the coil mounts and cleaned the connection for the ground. With every carb cleaning and jet change I have tried running it with and without the TPS connected. I am stumped and frustrated. It doesn't pop on deceleration. It will idle (not smooth). Anyone else have this issue? Is it electrical or am I missing something in the pilot circuit?