I was having the same problem. No popping in my case tho. Just major hesitation at 3/4 to full throttle. i played with jetting and couldn't get it right. Once i put in the shop i was told that the plug caps were bad and that was more than likely my problem. I was getting other upgrades so I didn't feel too bad about not catching a simple fix. Check plugs wires, cap, spark plugs, and other electrical components. the needle shouldn't be ur problem at full throttle. Im sure someone would chime in to rule that out.