I've run my engine quite a bit with just the external parts of the governor removed without any problems. All the internal parts do is turn the control shaft so that when it is connected to the stock levers, it can work the throttle plate.
The stock "throttle" lever only controls the operation of the governor, not the throttle directly. With, the external parts removed, the shaft may still be turning, but it has no effect on the throttle plate, therefore rendering the governor null and void. Simply put, the control shaft doesn't know it's been disconnected, but it no longer controls the throttle plate, you do.
There is a topic elsewhere of how I built the throttle linkage to work on the throttle plate directly. I'm sure there are simpler, maybe better ways, but this worked for me.
http://www.motoredbikes.com/showthread.php?t=8313