Kmot,

They are pressed in, not threaded. I had all of my flywheels milled down for weight, cooling and to fit inside the fuselage(for the DVII),so the guys just drilled out the top of the pins before milling. Those pins are hardened, by the way. If I remember correctly,Propnut said he got his out by prying them off with a screwdriver. I tried this when I first got my engine to see if I could get them off, but gave up for fear of breaking something. Also, a couple of my flywheels were also VERY difficult to get off,even with a flywheel puller, so perhaps these things vary from engine to engine