I have a 150cc 2 Seater gas gocart that I used for about 2 years. The starter motor stripped a gear 3 months ago and I decided to convert it to Electric Power rather than fix the gas engine.
Controller - $300
Motor - From old golfcart ($600 in store)
Wire - $20
Misc nuts/bolts - Already had them ($30 in store)
Contactor - $25
Diode and Resistor - $10
Sprocket - $35
Aluminum Plate and Bar - Already had in my garage.
Misc stuff that I had - $10-50
Step 1: Motor
The label is worn off the motor casing but as far as I can tell its specs are as follows:
Type: Series Wound DC Motor
Max Current: 300A
Cont. Current: 100A
Max HP: 15
Cont. HP: 5
It was pretty rusted up and the pulley that was on it was a pain to remove. I took the motor apart and cleaned the dirt out of the coils, brushes and also greased the bearings.