so what kind of hp? 750 is kind of vague.
also, pretty much all the good bikes, yes they are battery ie DC driven but the motor is actually 3 phase AC. and they have several with a pretty hefty power density .vs. weight. Energica is a prime example of this cutting edge tech put to use. This is why I mentioned generators too. Generator / Motor 3 phase, the only difference really is direction of current flow.
A DC motor, can be crudely simple, you essentially turn a rheostat for field strength to make it go roundy roundy, but not much finesse there. it'd be a cheap work on a go cart or similar install. or go 3 phase ,but you have very precise and predictable control via the inverter / vfc. i mention 3 phase also because inverters/vfd's are widely available from 3 to 5 hp up to thousands of hp. What do you need type thing.
im sure if you searched alibaba you could get some ideas.
aaron