http://www.menintools.com/linkage.html here's pic's of govenor linkage
and here's pic's of the throttle to govenor arm from the kart the kid's are actually driving right now-sorry for the quality and all the dust/dirt!
hope this helps with that problem.
To add a kill switch I need to know if there is a kill switch already on the side of the motor. If there isn't you'll have to pull the side cover off the motor and attach a second wire from one of the coil leads to get it outside the cover and to a switch location of your choice.I can walk you thru the process if needed.
If you can post pic's like Buggymaster asked it would help us to see possible issues