One thing you should know is that it is not against the law for you to ride a motorized bicycle at age 14. It is just against the law for you to ride it on a public road. You can ride it on a private track or on private property. I just thought I would tell you that.
If you do decide to ride it under age you should make sure that you have a DOT approved helmet and that you obey all the traffic laws. If you do ever get stopped by a cop you should know that many cops don't really know the laws about motorized bicycles. Also, never refer to your bike as a "motor vehicle" when talking to the cops, use the term "peddle assist bicycle". I recommend that you wear sunglasses and if you see a cop, DON'T PANIC, just sit up as tall as you can and don't look at him, look the other way so he can't see your young face, just pretend like you don't see him or that you are messing with your bike or something. Also, another thing to think about is that it's not against the law for you to ride it if the engine isn't running, I mean, as long as you are just peddling. The cop would actually have to see you with the engine running, riding it on a public road in order to bust you. Just something to keep in your mind. Remember, it's not a motorcycle, it's still a bicycle.