On two previous engines I have used purchased cast iron rings. They both performed very well. I am at a loss why this engine has no compression when dry, and by dry I mean no pool of oil setting on top of the piston. I have just looked in detail at both previous engines where the purchased rings worked fine, and in both cases I see that I lapped the cylinder with the piston which was to be used in the engine, then added the rings to the piston afterwards. On this current engine where I am having so much difficulty, the piston was deliberately machined to 0.002" less than the cylinder bore. On my engine "Thumper" I made a note to myself saying that even though I had used the piston to lap the final cylinder bore, it wasn't a tight enough fit to run without the rings. There is a lesson for me there. Even though I have read in numerous places that the piston should be 0.002" smaller than the cylinder bore, that doesn't work for me. I just paid $32 for another piece of cast iron 2 1/2" diameter x 4" long to make a new cylinder. I will bore it to almost final size, then use my new piston to lap the bore to final size.