Well, let's start with the tires:
Foam tires generally get the best traction, but they don't last long. I would get some belted rubber tires. For just messing around I like the HPI Advan tires. They have good traction, and last pretty long.
The piece on the left of the pic, the round cylinder shapped copper piece is the comm. You need a lathe to do it. If you don't have one, ask at your local hobby shop or at the local track. I'm sure someone there has one.
As for the spur/pinion combination, that sounds a little high to me. Once HPI's web site gets back up (www.hpiracing.com
) they will have some setup info and gear ratio charts there. You will notice a difference if you change your pinion and/or spur.
If you take the number of teeth on the spur gear and divide them by the number of teeth on the pinion gear you get your gear ratio. Take your combination: 93 divided by 21 = 4.42. If you raise that ratio, you will have more top end speed, but less low end. If you lower that ratio you will have more low end but your top speed will be lower. To lower the ratio, use a smaller pinion or larger spur. To raise the ratio, use a larger pinion or smaller spur. But don't change too much. If you over gear a motor (make it try to run a gear ratio that is too high) you will overheat the motor, and possibly damage your speed control.