Re: Looking to buy first bike engine kit and i need help deciding which is the best?
I really like my GenV from MotorBicycleRacing. Much nicer overall quality with the upgraded hardware and better balanced crank.
I got nothing but good customer service and would not hesitate to buy another.
Keep in mind, ANY engine will die under abuse so don't be too surprised if you find yourself replacing motors quite often.
From the sound of your post, I suspect you are going to be breaking a lot of stuff.
Honestly? If you really want to do 40+ all day long, you might be better off with a custom build with the parts to handle abuse. Better brakes, stronger frame, bigger engine, etc. are about the only way you are going to get the speed you want with any chance at reliability.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.