My mini bike took full speed off with me on

That sounds like a painful experience, fortunately it doesn't sound like you were hurt that badly, I know someone who spent 3 months in the hospital for a similar accident.

It's not the governor, the governor is there to limit revs and reduce power, not keep them up, and the way they work is very unlikely to cause that issue. This sounds like a classic stuck open throttle problem. When you twist the throttle open on your handlebar it pulls a cable (similar to a bicycle brake or gear cable) which on the other end is connected to the throttle control arm. When you let go of the throttle a spring attached to the throttle control arm pulls it closed, causing the throttle on the handlebar to close too. So the problem could be in one of the following areas:

• Stuck carburetor: a carb is a mechanical device that mixes fuel and air, your carb may have seized up in the open position. If this is the case the carb must be taken off and completely refurbished
• Stuck throttle cable: the throttle cable is usually stranded metal inside a smooth sheath, grit can get in between the cable and the sheath and stop it from moving, or braids of the cable can snap inside the sheath
• Broken throttle twist grip: the mechanical parts of the throttle twist grip could break and stop it from moving. This is rare
• Broken throttle return spring: this is the spring that pulls the throttle closed when you let go, if the spring breaks your throttle won't return to idle unless you twist it back

With the engine off try twisting the throttle, if it doesn't move or moves slowly you have a problem with the cable or the carburetor itself. Disconnect the throttle cable from the carb's control arm and move each independently, if the throttle still won't twist then the cable's probably seized and you'll need to replace it. If the carb control arm won't move it's the carb that needs work. If the throttle moves back and forth fine but it doesn't snap back when you let go then it's probably the spring.