Hello - I've been looking for one of these for a while and
I read the following about them (a super rare part):
"Basically there were a few types available ,the old Iron Horse did a bit of a retrospective on them in the late 70s.
One type of timing cover was made by John Glew of Bell Auto Parts ,they were cast up in the late 40s.
Lou Kizer of San Diego made some too, and they had a tacho drive at the front of the cover being driven off the generator pinion,they might have been the bell ones recast, but I dont really know.
Larry Howard of Award Cycle made some as shown on one of his bikes below (1960s).
The Iron Horse article said that the patterns for the Larry Howard cover were later owned by Jungle Jim's in Lynwood California."
If anybody knows of one for sale for a rigid generator model I'm willing to pay up to $1,500 for one to dress up my 1952 triumph custom.