Mikuni HSR pumper - close but no cigar

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!!!

back the pump screw out till it responds clean.you will increasing the gap a bunch.

back the pump screw out till it responds clean.you will increasing the gap a bunch.

Thanks, that did it. Now that that's fixed, I have another small problem: at a steady 1/4 throttle, it sputters a lot. Any more than 1/4 throttle, it clears up and runs fine. Any suggestions? Thanks!

go back to the stock needle position.

Works great - runs much better than ever! Thanks for all of your help! You're a GENIUS!!!

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