Is there motorcycle that goes 600 mph?
No, in fact the world land speed record on a motorcycle is less than 400 mph.
I am looking to but a scooter that goes at least 55 mph and I keep seeing things like 50cc and 125cc does this have anything to do with the speed?
Indirectly, yes. "50cc" and "125cc" refer to the displacement of the engine, expressed in cubic centimetres. In my jurisdiction, a 50cc. scooter is not capable of speeds in excess of 50 MPH, therefore you don't need a motorcycle endorsment on your driver's license. A 125cc. "scooter" is legally a motorcycle, and there are 125cc. bikes that are capable of speeds in excess of 100 MPH. There are also 50cc. scooters that will exceed 55 MPH…