How the engine recovers from hesitation is what tells you whether it was too lean or too rich.
If the engine comes back with instant power cleanly, it was too lean.
If it burbles back into operation it was too rich, as it takes a few fire cycles to clean up/clear out the excess fuel.
It is not normal to have hesitation from throttle twist, unless you twist it more than half of available travel. Suddenly opening the slides at low RPM negates carb throat vacuum, which is the only thing pulling fuel into the carb throats. No fuel - no power. The only pressure to push fuel through the jets comes from outside atmospheric.
There needs to be rapid airflow through the venturi for it to create significant low pressure levels. Otherwise the only thing to make fuel draw is the downward fall of the piston on the intake stroke. With the slide snapped open, the intake stoke vacuum is equalized very quickly, quicker than the fuel can be drawn into the carb throat. All the CB550s are wheezy in this regard when the twist grip is abused.
BTW, the air screws on the early carbs are adjusted to get that 1/2 twist throttle response (in any gear at low RPM). Mark your throttle. If it wheezes, the air screw gets turned inward just enough for it to stop doing that. More than what is required, adds to plug fouling. You should also be using D7EA spark plugs, unless you are redlining it through desert heat.
