Regarding the gear drive unit with 13:1 gear ratio we could help with determining how to incorporate it into the drivetrain for a 3 to 4 MPH top speed. We would need to know all of the drivetrain details such as wheel diameter, sprocket sizes, and powertrain configuration. A drawing would probably be needed to successfully convey this information.
However, we carry gear motors that have low enough gearing to use with only a chain between them and the axle and have low enough gearing for a 3 to 4 MPH top speed. Using one of these gear motors would simplify the drivetrain considerably compared to using a gear drive unit which would need two chains to operate.
Please let us know your thoughts on this or if you have any questions.
has any one added electric assist to a DINO KART
We have sprockets, freewheels, and freewheel to axle adapters that can be used to run power from a gear motor to the axle. Here is a link to the page that these parts are sold on: https://electricscooterparts.com/bicyclesprockets.html