My crf230f bogs and studders under WOT. I have the Honda hop up kit with 132 main jet, full power needle clip on 5th notch, and 45 main jet. I'm running a k&n air filter with pro circuit t4 exhaust. I took the tip off the exhaust and it started sputtering under WOT and has not stopped since it started. If I put it half choke it doesn't sputter as bad. I also drilled holes in the airbox for more airflow so I'm guessing its running to lean. Somebody please help!