Originally Posted by OkiThumper
Thanks for the Mystery Oil tip, JKinTX. Interesting that one takes the plug out. I thought it was the compression that splayed the ring out to wear in. However, that it works is the main thing. I have a drill press stand for an electric drill. I could rig something to gently hold engines still while running them. Come to think of it, I have a few other lapped piston motors needing break in. This sounds like a great and convenient way to break in, and be flight ready sooner.
You can try it with the plug in, the Rat guy told me to take it out as a Dykes ring seats different than a standard one. Try it both ways, see what works for you. You might want to use Marvel Air Tool oil if you leave the plug in, it won't mess it up (I'm not sure about the Mystery Oil). One other reason to take the plug out is to be sure you don't get a hydraulic lock with too much oil initially and maybe bend the con rod, or damage the crank pin or wrist pin.
I spun it for a bit, put the plug in and put a prop on and flipped it. Pulled the prop and plug and spun it some more. I think it took like three times and then it had real good compression and would hand start easily.