Do i need a motorcycle licence for my scooter/gas powered/49.5cc and its top speed is 40 mph?

i live in california

You need a M2 or M1 license.
With an M1 license, you may ride any type of motorcycle.
With an M2 classification, you will be permitted to drive a motorized bicycle, a moped, a bicycle with an attached motor, or a motorized scooter only.

So to answer your question, you need at least an M2 (which is just a written test)

NO.. Antartica has no rules for the road as it dosnt have a resident government..

Im just guessing you live there....... no profile info so I had to be psycic....

Each state may be different, in my state you do not need a license to operate a scooter of that size, but you cannot ride it on the interstate highways or turnpikes. Check with your Dept. of Motor Vehicles, or get a Driver's Manual for your state.

Regulation for vehicle/two wheel type lincensure depends on what country you are living. Here is the logic - If a person that drives are required to have a driver license how much more the vehicle. You are using a road rigth of way when you are driving, and they are subject of an accident. What ever happens on the road you can be easily trace for investigation and be responsible for all the things.