The Hick-up would tell me::: that it May be too small a low speed jet (Lean) or a small leak in the intake manifold OR the excel-Pump NOT giving the **Squirt Needed to increase the RPM...
The **squirt can be checked by watching at the carb opening(air filter off) and a Nice Full stream of raw gas should be squirting at the center of the Venture/butterfly opening... When you twist the throttle wide open a good full flow is needed......
On the Idle Mixture screw the needle out 2.5 times. Take the bike for a ride of about 15 miles. With the engine running slowly screw the needle in until the engine starts running rough. Screw it our until the same thing happens. The ideal spot is half way between the two spots. If the engine hiccups on early throttle openings then slowly increase your accelerator pump and blip the throttle. Listen to see if screwing it out makes a difference.