Mopeds are 50cc with pedals like a bicycle to start the engine. Check out the photos tab..
Moped became a catch all term for 50cc bikes. Used for registration purposes...
Yes some bikes had a limiter in the cdi. But these are top quality Japanese and European scooters, speed limited for the us market. Your best bet is going to be identifying what engine the bike has...most likely a Honda or Yamaha clone. Finding an expansion chamber exhaust and upjetting the carb...that should get you a few mph.
Just so you know, these Chinese bike are known for bad build quality. Good luck tho