I have an Echo 23.6 in my Balsa USA Eindecker 90. The motor came out of a used blower and runs fine for it's age. Flys the big Eindecker just fine. I have a 21cc Echo trimmer motor with CH ignition I am finishing for a Seagull Models Edge 540. I figure it ill fly pretty well but won't be a rocket or an extreme 3-D plane. Good sport aerobatics should be decent though. It is a test for me and a few guys at the field to see how well we can do with the smaller gas engines. If this one is OK then the next one I am trying in this plane is a Toro 25. Same mounting pattern as the Echo to boot.