RE: 30cc Edge 540 build
Last week, just did the maiden with mine (at 5,000' elev) with the OS 33 and stock muffler and it's got plenty of power already and that's with an 18-8 break-in prop and 20:1 break-in mix. If it were me, I think I'd try something like the OS33 (or maybe the new DA35) on a pipe before thinking about a 50cc motor on this size plane. By the time you get it balanced with a 50-55cc, wing loading will be astronimcal for the 8500' elev at Bogota.