Andy,

You had asked for some pictures on the Kioritz, however I don't have anything. I do have some on my first proof of concept effort on a Mac 21 cc. The engine was basically worn pretty good and I thought I'd try it out on it ratha than one of my "good" engines. I could only get it to run sort of on a high (30%) castor mix because of the worn rings. It didn't run very long before the crank gave out. It did show that there was enought material in the cylinder to turn it out and mount a conventional contra piston and head. The pictures are not very good, but you can get the idea of how I did it. The Kioritz was a little more difficult because it had an angled spark plug hole and didn't have as much material at the top of the cylinder like the Mac which had a center, upright spark plug.

I have been wondering if one of Motorboys ignitors might be the way to go. Cut down the cylinder base till you have about 10 thou clearance after cutting out the squish band from the cylinder head. Use the Ignitor to adjust the compression ratio. It would be easy enough to try.

Incidentially, on the Kioritz, I replaced the stock rings with rings from Frank Bowman. They are pinned, but made so that they cover the pin and have minimum clearance and thus minimum blowby.