I found this off an old Laura M56 engine (Batavus/Trac), that had been modified to not use the famous toothed belt. Cool farmer-john mod since the carb comes off easily now.
I can't figure out how to get the sprocket off, though! If I immobilize the sprocket and turn the nut at the other end of the shaft, I can actually spin the shaft underneath the sprocket. That means it's not welded to the shaft, and any Woodruff key is broken. Still can't pull it off, though (and thus can't remove clutch or crack the case).
There's a little screw sticking out the side of the back, which you can see in the 1st pic. I filed a notch in it to try to screwdriver it, but it seems to be fixed in place.
Anyone seen one of these sprockets before, or know how to remove it?