"The ryobi would be too long unless you modified the firewall.Wich will be bad because thats where the front landing gear cross leg almost ends up. "

If I make a hole in the firewall for the carb and turn a shorter hub it looks like it may fit OK. I would have to make a thin muffler box with the stacks running alongside the case and out the bottom. The prop would end up about 1" ahead of the cowl.

The other option is a Zenoah 41 cc. It is from a backpack blower. On that one I would have to make a 90-degree bend in the carb manifold. That would allow me to put the carb right next to the case facing down. That with a thin muffler that engine would fit too. It is such a reliable engine I am warming up to it for this plane. How does it work out to put a 90-degree bend in the intake manifold? I am inclined to believe it would rob a little power but how much? It is "to much" engine for this plane so I probably would not miss a little horse power.

I really want to avoid unsightly bits sticking out the side of the airplane and I don't want to buy a zenoah G-26.