Bill,
Thanks for doing the thread.
Is there a piece of plating hanging on that upper transfer floor?
Is the chamber plated or bare?
Looks like they casted the exhaust port shape perfectly, just upside down.
I'd cheat on that ex roof. Just bevel the plating more in the center of the port than the outer. You'll effectively show the rings a rounder roof.
Yup, that's a little chunk of plating, one here, one there. Plated over casting flash where there's no bevel.
Chamber is plated. There's an odd looking dull, dark brownish, maybe 2mm ring at the top of the bore that almost looks like the plating ends but it still feels hard like plating. Might hone it/clean it up just a bit and see what it looks like then.
Really the floor of the exhaust port should have as much radius as is needed on the roof, the rings have to clear both.
Would likely have a nice exhaust note with the roof flat like that but I'd rather not chance it.
Yeah, I'll play around with the beveling on the roof and see what it looks like, the middle is pretty flat but toward the outsides it's well radius'd, I've seen worse on long running saws.
The bottom ring way clears the intake roof At BDC, so shape and beveling will come into play there also.
These two jugs are good there on beveling but again pretty flat.
Bottom of the skirt looks like it goes past the roof by about a mm at TDC. About 1.5mm left on the exhaust side skirt at TDC so some leeway for dropping the jug.
Another .5mm on the (below the pin) piston height wouldn't have been a bad thing...
