Slow pick up & exhaust popping

[pouchy750]

It's time to try & get the 1979 CBX1000 to run properly this year.
I rebuild the crabs last year with new float needles, repaired stand pipes in the float bowls & replaced the many cross tube o rings. The carbs were completely taken apart & all passageways & jets were clean. I also extracted the slow running jets & they were clean. There are no fuel leakages now.
Once the bike has started & warmed up, the throttle pick up is very hesitant, as if it wants to stall & there is also a slight popping in one exhaust system.
Is it running weak? Or do I have a coil failure?
Once the revs are above 3000 it wants to run properly, but I have to slip the clutch to get to that rev range.
I checked the diaphragms on the air bleed system & accelerator pump when the carbs were apart & they were intact, but not sure how stiff they should be. Could this be the problem?
Any help would be greatly accepted. I'm about to give up & sell the dam thing!

[daves79x]

Are those King crabs or Snow crabs? Sorry, couldn't resist! Seriously, are you sure you have good compression on all cylinders? Popping is a clue that some valves are not sealing at low revs. I'd check that and also be sure you have no intake or exhaust restrictions.

Dave