I have a wr 400 '00 that is big bored to a 426.It has 13.5:1 aries forged piston,bk,hb mod,yz timing,stock uncorked pipe and carb stop cut.I am tring to figure out the carb tuning.The carb has a #170mj,#42pj,obdrs needle clip in #3 position. I also run 105 unleaded fuel for the compression. It runs great and starts on 1st kick every time but it still stumbles if I hit the throtle hard from idle. My altitude is 900'. Can anyone help me on the fine tuning with higher compression on this bike. Maby one of you guys have done this to your bike.