alot of times the engine will over revv and its usually because the governor is not hooked up correctly.
Here it is written out a little better.
Step 1. set throttle to fast position.
Step 2. losen governor linkage arm and turn governor input shaft clockwise till it stops.
Step 3. retighten linkage arm and be sure that the throttle is open to full.
Step 4. set throttle to low, the throttle linkage aon the carb should close a little bit but not always.
Step 5. start engine and see if it runs at the correct rpm, if the engine revs up at full throttle you did something wrong, if it doesnt go crazy and just runs fast, simply loosen up on the governor spring tension, if it runs to slow, simply tighten up on the governor spring.
Fuel mixture and idle adjustment is shownin the video.