The stock jetting is grossly rich and needs to be changed whether you modify the air box lid or leave the bike completely stock. Check out the JustKDX web page and click on Tech Tips. You'll see a carb tuning guide there.
Careful with the double posts! 8 minutes after your question on jetting changes here you post the "Airboxmod/jetting changes" thread, my patients are wearing thin! :|
well what i did is take a visable marker and draw where you wanna cut i opened up air lid fully and and sum more holes in top where i couldnt but and its still exstremly strong and i went to the sides and cut sum large holes in both sides of air box if thats not good enought i dont know what is lol
roger kdx 200 15/48 ratio fmf fatty tourqe reeds and so on and so on