CARBURETTOR Problems In Low RPMs

[Fazerider]

It behaves like a ignition retardation when trying to overtake quickly. The engine sputters and looses power of the throttle is twisted quickly. But if I ease it in slowly then I can get through the whole range.

I'd guess that's one or more of the carb slides jamming because of the sudden large pressure difference, rather than rising smoothly.
You may be able to feel that if you try raising them one at a time by hand, though obviously that's a carbs-out job.