Can i ride a motorbike without a license up to a certain power (cc)?
 

if so, what cc? many thanks in advance

Usually 125cc in IL

yes. The law states that you must have a license to operate any vehicle which reaches 55 miles per hour or more. I am not sure which one that is though.

No, you should posses a provisional license to ride a motor bike

you can with a provisional up to 125cc but you have to display L plates

It depends on your location. I know for a fact in Illinois and Colorado you not only need a driver's license but also need a special category (L for small, M - for larger bikes). In Austria, on the other hand, you need a regular driver's license if you are less than 21 yo, and no license otherwise. This applies to smaller bikes/scooter up to 125 cc.Check with your state dmv.