Pat--I feel really good about this. Even though I felt very confident about being able to design a new/different engine, it was a great leap of faith to ask 10 other folks from around the world to join me, before I had even proven my design. There were a couple of times when I had that "Oh God, what have I done??" feeling, especially when I was getting the intermittent firing from the old 12 volt coil, which is very difficult to diagnose. That was the main reason that I went to the CDI ignition.--In general, it either works or else it doesn't work, making it a lot easier to diagnose why an engine won't run consistently. The download link I have posted to the drawings will get the water cooled version, the air cooled version, the version with ignition points, or the version with CDI ignition. The engine is out in my main garage, running away like a trooper, as it has been for the last two hours. This is a happy ending to a summer long story. I expect I will see a lot more "Rupnow engines" built, now that the design has proven to be a success, and the drawings are all free. ----Brian