I am going to have a go at making a flame licker engine, and like the look of the Poppin.
After teaching myself how to work harden stainless

, I am going to try again with some cast iron.
Many plans and descriptions of building these engines talk of lapping the cylinder for a good fit, but I can find any details of the process.
Are there any web sites with good instructions on how to do this, preferably with some pictures, or video?
Failing that, anyone kind enough to put together a tutorial?