'74 CB750 sputters at 1/4 throttle

Here's the deal: Up to right around 1/4 throttle engine responds beautifully. 1/4 - 3/4ish throttle she bogs and it sounds like it's just sucking air. If, however, I crack the throttle past the 3/4ish mark she lights right back up and takes off. Additionally, one I crack it past that 3/4 mark I can roll the throttle back into the 1/4 - 3/4 range without it sounding like it's sucking air, for the most part. My guess is needle setting is too lean? Maybe drop down a clip? I can't remember for certain, but I want to say the clip is set in the middle. I'm running a 4-1 exhaust & velocity stacks. Last time I took the carbs apart was last year so I don't remember what I've got in there for mains, I think they're 115s, possibly 120s. Float height is spot on though, have gas and spark to all 4. Thoughts? Thanks.

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sputtering/burbling is too rich, so i would lower the needle by raising the clip 2 positions.

Huh, I had figured air sucking sound meant too much air! I'll give that a try!