A while ago I converted a Ryobi 31cc to airplane use. I flew it a few times on this scratch built coroplast plane I made. It worked fine. I just used the stock Walbro and gutted the muffler to get a modest 7000 RPM with an APC 16x8 prop. This turned out to be just the right amount of power. Not overpowered, but not underpowered. Full throttle wasn't needed to stay airborn.

The engine and plane has been collecting dust for about a year now, so I decided to mess with it again. However this time I wanted to run it on alcohol. I though maybe I could get a few more RPM's. So made a crude little adaptor out of some aluminum and JB welded an OS 4B carb (came off an OS.40 but has about the same bore (maybe awee bit smaller)as the stock Walbro). For fuel I just used some denatured alcohol and some Klotz Super Techniplate at 5%.

IMO it runs better now. I mean it actually has a midrange instead of just high and low like it did with the Walbro. Plus the idle is more reliable. Just all around smoother.

Yes fuel consumption is greater, but it doesn't gulp fuel.

RPM is the same as with gas.

I think I could have squeezed a bit more RPM out of it over the gas if I used my Super Tigre .40 carb. It is quite a bit larger than both the stock Walbro and the OS carb.

[youtube]http://www.youtube.com/watch?v=yXqBYO-ApsI[/youtube]</p>