Are mini bikes illegal in Maryland?

You can own them, you just can't ride them on the street. This is comong from someone that owned a few (still own one) and has been pulled over for riding on the street. I was told that I could get fines for operating an unregistered motor vehicle (you cannot register a minibike in MD, although I have seen a mini chopper tagged?), operating a motorcycle without a license, riding an uninsured motorcylcle, and more. The officer said he could easily give me $1000s in fines. Lucky for me, he decided to tell me to take it home and keep it off the road.