I am currently rebuilding one of these engines for use in a miniature railway locomotive.
A major problem I have is that it has become obvious that the flywheel has been loose on the shaft for a while, and the movement of the key has damaged the keyway. Effectively it has widened it by pushing the keyway to one side.
It looks like I will have to remove the whole crankshaft so that I can machine it.
Does anybody have any idea what material it is made of? In particular I was thinking of building up the side of the keyway with weld then machining it in the lathe, finally recutting the keyway using my shaper.
Has anyone else come across this problem?