The only dirt bikes that are legal in all states are Enduros. That is dirt bikes with turn signals, headlights / taillights, and a license plate. Any dirt bike not equipped with these is not street legal in any state.
if it has the speed governer take it off then .... that doesn't even make sense. Google your question. You'll find that you can buy a kit from someone like bajadesigns and get it legal, but it all...
A street legal dirt bike is any dirt bike that has a four stroke motor, head lights, brake lights, turning signals, a spark arrestor in the silencer, and street legal on-off road tires.
Here in NJ we buy them street-ready.. I have never heard of anyone "converting" one to street-legal status, but i suppose if it were to pass inspection it would be legal. I think it needs to meet...