Where I live its illegal to drive a 4-wheeler if you are under the age of 16, but if I was under age and driving on my property could the cops come and give me a fine?

To the best of my knowledge the laws governing 4-wheelers are different from state to state. I lived in a state where police had jurisdiction over 4-wheelers on private property but that was also a state that had a large percentage of private roads (no County roads).
In most states 4-wheelers can't be driven on paved roads, so the only place the law in your state could apply would be on private roads and/or property. But you have to research what exactly the law says for your state and some counties and cities have their own laws also.

Hello rex:

You don't need a drivers license to operate a motor vehicle on private property. If you got a ticket, fight it.

excon

Let me clarify what excon is saying. You will not violate the law by driving anything on your OWN property (property owned by your family). Nor could you be ticketed for driving on property owned by someone else, if you have their permission.

However, if you use private property without permission, they you can be in trouble.