I have a GMS .47 on an airplane. It runs great, but I can't get the engine to shut down. I pulled the throttle and trim back and even put my finger over the carb and it keeps idling. It is obviously getting air from somewhere. Any ideas on how to stop this? It is obviously not a big problem, I just want to have complete control of it.

I read somewhere that after-run oil should be put directly into the cylinder through the glow plug port. It seems to me that I don't really want to take the glow plug out after every flying day. The thing I read said that the after-run oil would eat away at the carburetor's rubber gaskets.

Thanks!

Herb