Hi, I discovered this forum while searching for projects to build with my lathe. I purchase a lathe around 4 months ago. I have never used a lathe before but wanted to make an IC engine. First I just made some simple bushes, Kurled knobs, ornaments and a Gyroscope.. I found the MP3.2 plans on this site so decided to make it. I have attached a photo. I was wondering what the starting technique was. I have not been able to make it run for more than a few seconds. At first I had very little compression so I grew the cast iron piston by heating then quenching in oil, then tempering. It grew so it no longer fit into the bore. I then lapped it to get a push fit to the top of the bore. It seems to have good compression now from what I can remember from my RC flying days when I was in my 20's. I get it to fire but it only runs for a few seconds maybe 5 or so at what sounds like an old 4 stroke idling. One thing I didn't do was the little ledge on the backplate I circled in the attached 2nd image. Mainly because I didn't understand what it was for, it did not seem to be needed for piston clearance. Whats it for? Anyway I was hoping I could get it to run at least once. Thanks for Reading.