RE: 55 cc engine
They look to run good, some tach readings and weight would be helpfull though.
Yes there is several 50CC engines out there, but there is alot of intrest in that size of plane right now, if you notice the 50CC planes are growing to where a run of the mill 50 CC engine won't fly them to good, at least not here at my alt.
Untill my testing is completed i'm not sure just what I am going to do.
But you are correct in saying it's unlimited as to what a person can do if they want to.
I did run the engine again today for another tank of fuel. RPM's around the same as the video. 7850-7900 fairly constant. Should improve a little after its fully broken in.
After the holidays are over then I can do some serious prop testing, outside I hope and see where I stand..
I'm not sure about a saw cylinder, I would have to look into the specs for weight and the power band.