A series wound DC motor of a few HP can be quite a handful with an across the line start.

Simply using it as an example!
Max.

 

It would seem that many of these bikes and go-carts now use a Radial or Axial flux motor, often eliminating the need for a gear box, as it has been done in washing machines, also RC motors etc, often termed out runner motors, and require a 3ph controller.
Max.

 

Awesome would you know a good controller for a motor like this or a thread that I could find out

Everyday Practical Electronics published a project for exactly that a couple of months ago.

 

It would seem that many of these bikes and go-carts now use a Radial or Axial flux motor, often eliminating the need for a gear box, as it has been done in washing machines, also RC motors etc, often termed out runner motors, and require a 3ph controller.
Max.

My response did suggest motor, controller, and battery. All three are required unless it is one of those situations where you never have to back off. In that case you are shy on horsepower..