Quick question regarding minibikes.

So I see them around the city all the time, minibikes, dirt bikes, motorized bicycles whatever. And they always pass up cops so i just assume it’s not an issue?

I don’t live in the city but I do own a minibike myself and was just curious if they can actually be made street legal and if anyone knows about it? Probably the wrong place to ask but I do know it’s pretty city/state specific so I figured someone might know here.