Optional: While the crank case is open, if you are running an aftermarket carb with external or rev limiter built into the coils you may take this opportunity to remove the governor shaft and gear. To remove the governor gear from the crank case- just use a couple of screwdrivers to pry the gear up from the bottom- it will just pop off then remove the governor washer leaving the shaft in the case cover. To remove the governor arm from the block, remove the split rings from the top and slide the shaft out the bottom. You will also want to remove the bushing from the lower mount (it can vibrate loose without the governor arm to hold it in place). It seems to be loctited in place and I threw some heat on it and drove it out with a small socket and tack hammer. To seal the hole in the top of the block, you can use a 2” long ¼” or 3/8” stainless steel bolt and flat washers, a lock washer and nut (not a Teflon lock nut). Fill the cavity in the block left by the governor shaft with high temp silicone sealant (Black RTV or equivalent). Apply a little around the top surface of the block. Then put a washer on the bolt and insert it into the hole. Install the washers and nut on the inside and tighten it down. Wipe off any excess silicone on the inside. Apply more silicone around the head of the bolt to ensure no leaks and go about sealing up the crank case cover. 

Bolt Replacing Governor Shaft:

Remove Governor Shaft Bushing: