There are different types of mini motos, these are as follows:
mini motos These are the standard mini motos, these are usually 39cc but can be purchased up to 49cc, and in some cases kits can be bought to increase capacity to near on 60cc. These are very small bikes and are race scale replicas of the real things. Start at around 2.5hp and can be purchased now at up to 15hp. These have a two stroke engine.
midi motos These are slightly larger then the mini motos, this isto ensure all riders are capable of riding them. These usually are no less powerful then 4.2hp but can be bought up to 15hp.
pocket bike American term for mini moto
mini quads These are around the same size as the mini motos but in the style of a quad with four wheels. These are usually around 3.7hp and not usually as fast as the mini motos.
mini sidecars These are mini motos with sidecars on the side of them just like the full size racing sidecars. Again using the same two stroke engine as the mini motos.