A simple test of the governor:
Set the hand lever to the idle position. The carb should be held against the idle stop screw. If it's not, the linkage is out of adjustment.
To determine if the governor is working, and the length of the gov to carb link, try this:
Pull the pin out of the yoke end of the link. Set the hand lever to about mid position. Hold the rod connected to the carb back against the idle stop with one hand, hold slight forward pressure against the governor arm, have an assistant start the engine.
Slowly and carefully bring the RPM up while feeling for the governor arm to push back. Be careful not to over rev the engine, but at some point the governor arm will reach the end of it's rearward travel. Note that position. Shut the engine off, adjust the length of the carb to gov link so that the carb is against the idle stop when the gov is at the end of the noted travel. If you get no push back, the governor is not working.
If all looks good, review the position of the linkage with the speed lever at idle, the carb should be against the idle stop. If not, loosen the U bolt and rotate the linkage until it is held at idle.
Try starting and bringing the speed up. It should max at around 2200 RPM. Adjust the final speed with the U bolt.