For some reason or other, at the moment, I seem to be rebuilding a lot of Harley motors for one of the local bike shops. One of them they gave me to do had a "little piece" broken off (their words not mine!)

The repair looked a lot worse than it was to actually do as it could be conveniently clamped up with the interference fit bolt that is used to centralize the casings, so all that was needed was to vee the broken part and the crankcase very deeply on each side (nearly it's whole thickness) and then bolt the 2 halves of the crankcase back together and weld as much of it as I could get to.