Hesitation on low RPM acceleration?

I hope some of you can give me some ideas of where to start looking for a solution.
73 850, boyer and power box, battery fully charged, valve clearances fine.
Starts first kick, when applying throttle from 2500 to around 4000rpm the motor does not pull cleanly, very brief "hics" like not enough gas,
then pulls just fine above 4000rpm.

Brand new spark plugs, single Mikuni same settings for years, pulled it, cleaned and verified jetting.

In the past what I suspected as carburation turned out to be electrical upon resolution of problems.
This time, I can't find anything wrong, nothing loose, grounds, etc.
Wonder if it is possible I got some bad gas recently, same Chevron 89 as always, will drain gas and refill will fresh.

Any thoughts?
Would appreciate, thanks.

highdesert said:

Starts first kick, when applying throttle from 2500 to around 4000rpm the motor does not pull cleanly, very brief "hics" like not enough gas,
then pulls just fine above 4000rpm.

Click to expand...

HD, sometimes it's easier to go by throttle opening rather than RPM. I've put tape on my twistgrip with marks to be able to tell where it's at. You can tell if you're on the pilot, cutaway, needle, ect. Are you using an old tank of gas, or maybe just a bad batch? It happens.

Bob, I think you got it!
After reading your post I drained the tank and took the petcocks out because the flow was pathetic while draining (had to turn it upside down).
I removed the old petcock filters which looked terrible and put in some old ones without filters but had good flow.
New tank of premium and she runs really good, no hesitation.
Thank you for the suggestion.

NOW, I am at 6000 feet altitude with sea level stock mikuni settings, riders behind me report slight smoke coming out of both exhaust on acceleration.
I think I am too rich at mid throttle, which drop the needle a notch and see.............

If anyone is at my altitude are running a single 34 Mikuni, can you tell me what needle jet size and needle clip you are in?