I live in Asia, where Honda sells several scooters that are 100-125cc. Some of these scooters are fully automatic with CVT/V-Matic transmissions (no shifting, no discrete gears, no clutch). Some of them are semi-automatic with discrete gears, shifting, but no clutch.

For 2 such bikes that have an engine with identical displacement, torque rating, and power rating, but one fully automatic and one semi-automatic, which bike can accelerate faster?

Please back up your answer with a citation/reference if possible.

I know that acceleration is somewhat operator skill-dependent, but please assume the rider is a "good, experienced shifter".

Bonus question: And how does acceleration of automatic and semi-automatic compare with a traditional manual bike (shifting, discrete gears, clutch), with all other things (displacement, torque, power) equal?

 

Any automatic will eat up a little more power turning the drivetrain than a conventional manual.

But, a CVT is perfect for smaller displacement engines, especially ones with narrow power bands, because under full throttle acceleration the transmission can hold the engine at peak power and accelerate by changing the gearing. This can produce quicker acceleration than a manual, which will climb in power with the revs until peak (power, not rpm), then fall off past it, potentially resulting in an average acceleration rate lower than the CVT equipped vehicle.

So, CVT vs. auto w/ discrete gears, all else equal, the CVT should win. Even more so since most CVT's lack a torque converter. CVT vs. manual, depends on how much power the CVT saps.