RE: mccoy engine
 

The Mcoys do not like any synthetic oil in them. As was mentioned they really like lots of castor, and they need to build up a "varnish" along with the proper fit on the piston. A lean run will kill them quickly.
I know a guy in Portland that is pretty much an expert on Mccoys. He reworked one for me that was a tired pony. Something about the heat treating on the piston, then he tapped the top of the piston lightly , many many times, then lapped it to fit the liner. Its a really sweet motor now. Saving it for my goldberg profile shoestring stunter kit I found. THis will replicate my first "big" control line airplane from my youth.

his contact info is
Name: Scott Riese
Email: [email protected]
tell him Mark Scarborough sent ya, his collection of mcoy engines has to be seen to be believed!