I looks like pot metal. The bell doesn't seem to fit tight on the crankshaft. When the screw is very tight I can cause the bell to wobble on the shaft by pushing on it. I first thought it was built in slop. My only throught was that the bell is held tight when the clutch shoes press against the bell. I am going to take it apart again and see if I can figure it out whats causing it not to fit tight.

Thanks for the comments.