The top speed of a motorized bike can vary. But let's first be clear...this is not a motorcycle. Nor would you want to be going those kinds of speeds on a regular bicycle frame. Here at PedalChoppeer, I only sell and use high quality engines. They generally give you 30-50mph. The top speed you get out of them will vary depending on what specialty parts you use.We carry a variety of high performance parts. For instance, one of our high compression heads will add 10- 12 mph to your top end. That is plenty of speed to really be a blast to ride, as well as get you where you are going in good time.
Don't forget, just because it is NOT a motorcycle, doesn't mean you don't need a helmet. Accidents can happen at any speed and this is faster than you would be riding if you just pedaled. My customers often prefer a motorcyle style half helmet like this one - http://amzn.to/1YFzn0E . I like the look of the flat black and it's light weight. It looks cool while still being DOT approved if you are required to wear a helmet where you are riding.