Here's an interesting problem. I've replaced the crank case pan on my BS model 125K02 due to a cracked mounting hole (no internal damage). When I did this, I simply placed it back on and did'nt pay any attention to the position of the governor. Now when I start it, (after adjusting the governor according to BS manual instructions) I runs extremely slow, "hunts and surges", and easily dies. If I back the governor shaft adjustment off the slightest bit, it runs too fast and vibrates. When I replaced the pan, should I have made sure the governor cup and governor shaft were properly aligned, or should it have self aligned?

the gov is on the crank housing right??

anyways, doesn;t have to be timed, all it has to doo is spin with the speed of the engine.

Try this... (if you haven't)

throttle all the way down

engine off

loosen gov arm so that it can move freely...

move the throttle all the way up..note the movement of the arm....

turn gov rod the directon the arm traveled when you put the throttle up....

tighten arm....

Done that. That's when it runs too slow. If I back off of that position just a hair, it runs too fast.

the gov might have been slightly open when you replaced it. The only thing that holds them on that little rod is a metal ring. If it wasn't pushed all the way down before you assembled it, it could be throwing it off, just that little bit... im not sure... are all of the linkages in the right spots??

All of the external componants arer in place. the only thing I can think of is the governor itself.