I'm trying to dial in my Mikuni HSR pumper on my 2000 XR650L. It seems to be running well except for one thing: when I pop the throttle from idle, it hesitates, blows a little black smoke out the exhaust, and has backfired a couple of times. My engine is stock, smog and snorkel removed, slip-on Pro Circuit T4. My carb is currently set at: 160 main 22.5 pilot 1 3/4 turns 96 needle, lowered 1 notch Any suggestions? Thanks!!!