Did a bit more work on the HF1E tonight. Raised the combustion chamber about a 1/16" so that the connecting rod is better centered in cylinder as it was scraping a bit on the top during part of the stroke. Then I removed the intake valve and filled the cap with lead. These two things didn't seem to help much. For some reason the engine doesn't ignite on every stroke, but every other stroke, or less. Maybe I have to play around more with the spark timing.
Charles Baetsen holds a Bachelor and a Master's degree in Engineering Physics from McMaster University in Hamilton, Canada.