Capt’n finished cutting and tested the second cylinder. Left exhaust duration on the second cylinder at 150* and there appears to be about 150 RPM difference. In other words 5* less seems to cost 150 RPM but is not considered significant. Other factors such as run time, temperature or humidity or needle setting could have contributed to the difference. May change my mind as testing progresses. Continue to believe California lean carburetion is currently the limiting factor but not willing to buy a bunch of carburetors for experimentation.

With Dremel tool and a tile-cutting burr the cylinder cuts like butter. It is a delicate but easy task. Didn’t touch any other ports. Matter of fact the transfer ports seem strange in that they are flat at the top, which is unusual and not understood.

Bill