Re: Standard upgrades for Motorized Bicycles?
A few things that come to mind:
Sick Bike Parts makes a good exhaust that almost everyone agrees on.
Of course a new spark plug
I would even say replace the spark plug wire with something like Magnacore.
A bigger sprocket if you don't mind losing a some low end power for high end speed.
Possibly a new carb though there is some debate about the benefit.
For some "not so performance" related upgrades:
Better grade mounting hardware
Better grade chain
Disk brakes for more reliable stopping power
Lower gauge spokes for the rear if you intend on using the rag joint.
Possibly repacking all bike bearings since you will be putting a lot more wear and tear then was intended.
Just a few things off the top of my head.