Shift Kit!
The key to acceleration and top speed is the shift kit or a NuVinci hub, connected to a powerful engine.
Whereas most MB's have constant gear ratios of 18.75:1(Staton) or 18.26:1(Happy Time with 44t sprocket), the shift kit or the NV hub can produce varying ratios of ultra-stump-pulling or "holeshot" acceleration ANNNNND freeway overdrive gearing ratios.
I wasn't actually "racing" the scooter. I wanted to find out if I could accelerate faster than the scooter and normal commuters waiting at the traffic light. There was no contest; acceleration was brutal. I have a ported Tanaka 47R engine, which wanted to throw me off the bike on every powershift.
Top speed is 39mph with stock muffler and short-shifting. When I install the Tanaka pipe and wind out the engine, it'll go faster if needed.
However, it's how fast I get to the speed limit is what satisfies me.
My first gear is 41.65:1 ratio. Too much of a granny gear, unless I'm climbing a grassy knoll. I can jump off the light in second gear, which is 33.85:1, third is 28.64:1, all the way thru 8th gear, which is 14.32:1. By that time, I'm cruising at the speed limit. In about 4 seconds, the scooter and the cars catch up and pass me by. I don't want to get caught breaking the speed limit. I MIGHT have to pay for that ticket.
My friend Rick has an 18.75:1 Staton gearbox, sprocket and a NV hub. His mind-bending low gear is 62:1! His high gear is 8.85:1. Using my GP460 engine and an ADA S1 pipe, top speed on the flats is 47mph, 57mph downhill.
Now that's crazy!