Hesitation at 4,000 rpms

My '82 kz305 developed a hesitation at 4,000 rpms, like it bogs down or low on fuel, something like that. Runs up nice to then and over that it goes great. I took apart the carb cleaned everything out and made sure to blow compressed air from a can to make sure all ports and jets were clear.Diaphrams were solid and good. I thought for sure that would solve it. Replaced points and condensor, retimed, adjusted valves. No air leaks around boots that I could find. New spark plug caps as well as plugs. I tried to adjust float level and think I did it right using clear tubing. What am I missing?

Petcock and filter clean?
Is it always at 4k in the same gear? That is, is it always at a certain throttle position or at 4k no matter what the throttle position is?

Perhaps igntion timing advancer is sticking.

Could verify advancer performance with a strobe type timing light, by watching the timing move quickly back and forth as rpm is varied by blipping the throttle.

Would in any event lube the weight arm pivot points on the advancer.
At the least, a drop of oil on each pivot point, which may be accessible through the timing inspection window.

Re-test with timing light.

If timing light shows erratic behavior of the advancer, would remove the advancer for inspection, cleaning, and lubing.

Good Fortune!

There is a specified protocol for timing where points are involved.

First -- dress and clean the contacts. May use a folded over strip of fine sandpaper pulled through the contacts.

Next -- set the gap. And re-clean the contacts.

Finally -- adjust the timing.

Good Fortune!

It does it in all gears at the same rpms regardless of throttle position, I will do the checks suggested, thanks !!1