How fast do you want to go? My first thought would be a stock 27T brushed motor. That would get you up to about 20 mph. They are getting so hard to come by at a good price. A new
Snow Panther 27T is about $26 or the
Integy 27T. I can almost guarantee those two motors are the same thing. There many more out there, just with different stickers wrapped around the same motor can. I only suggest those because you can change the brushes once they wear out.
A little more speed?
Snow Panther 21T motor.