Well, I went to Tractor Supply Center (TSC) today and all they had were imperial sized pulleys (1/2" and 3/4"). The motor that I have must be a metric size one because the 1/2" hub pulleys were too large. I bought some 1/2" hub pulleys anyway since I wanted to see if it would work as a proof of concept (and just around how much more power I'll need).
Now I just have to make a mount for the motor. I think I'll just use a piece of 2x6 wood that I have laying around and make a simple mount.
I took the motor, motor controller, batteries, and everything else out of the Razor. I tried to play with the motor controller. It turned out the "throttle" on the bike was only a switch and not a potentiometer. I tried using a 5K pot but the motor speed (unloaded) didn't seem to change any. I'm not sure if this controller is variable or not, but it wouldn't make any not to be, right? Maybe I need more resistance.
If I can get the pulley and V-belt on next weekend and cut the mount and drill it out, I'll be able to get the electronics in and the mo-ped on the road to test it out.
To answer some of the comments on the previous post:
1. Definitely 240 watts is too little, if that is the actual rating of the motor. Once I get this to work and can show proof of concept to my partner, my budget for getting a bigger motor should be approved.
2. I thought about a hub motor and might go down that route if belts/pulleys become too much of a bugaboo. It'd certainly solve a lot of problems except the financial ones -- most ones I've seen are $300-500 right? That's about $200-400 over my current budget (until I can prove that this will work, and that I haven't ruined my partner's mo-ped in the name of science).