if you shut the governor butterfly you can control the revs and then it is a problem with the governor springs. Put another carby on it and if it does the same it is the governor
Norm, on some of my mowers I disconnect the governor system and have the cable operating the throttle/butterfly valve directly. Call me a Control Freak :-)
For some mowing applications I like to be able to set the motor running at a particular speed, e.g. idling very slowly when emptying the catcher, or at a fast idle when doing a very light cut with razor sharp blades.
Pics below will show you the set up on the little Lawnkeeper.
BTW I note that B&S have carb options for High Altitude mowing. I presume that means smaller main jets - less oxygen means less fuel flow or a rich mixture would result. From contact with Muricans who are using chainsaws in the tall mountains they need to fiddle around with their carbies.
