The source of this piston is also amusing (I think). Some time ago I bought a replacement barrel on Ebay (My original one had a bunch of fins missing). The piston came with the barrel which had been machined to accept it. So, I now need a new sleeve. Maybe I'm missing something but I can not see how a domed piston would make for an improved WM20, and how it might be damaged by a valve in a flathead engine.
