I am getting a used Roketa Tahiti MC-03 scooter today. Is there some kind of speed limiter on these machines? If so, can it be removed to get upwards of near 60mph?

Are the engines easy to take apart and rebuild? I think it may need some work. I was told it has a slight oil leak. Maybe a half a quart every 5 to 10 fillup's.

yeah it is easy to take off the limiter man. There is this website that shows you how with detailed explanations and various pictures. As for the oils leak.... Roketa's dont have very highly ranked parts... I suggest if you are serious about this Roketa performing well, get an MRP Power Pack and switch all the Roketa Tahiti parts out for those. You will gain at least 10-15mph and these parts wont wear out on you.