Thanks guys for all the very good responses. For those of you that have the ZDZ80, and the Brison 5.8 - will either of them swing a 27 x 8 prop? I have read many responses, and they all settle in on a 26 x 10 as the favorite. I'm thinking that the slightly larger dia. and reduced pitch would be better for a Cub. I called FOX and they told me that the max. they recommend was the 26 x 10. Also - the FOX 5.8 has electronic spark advance, whereas the Brison has mechanical linkages. Have these linkages ever been a problem?

A lot of years ago I sold Sachs-Dolmar engines with linkages, and when they screwed up and advanced the spark too far - it would take out the engine bearings. I like the idea of the electronic advance.

After checking out the Brison engine web-page, thanks to Big Bird, I now believe that the right engine for the airplane is the Brison 100cc twin at $995.00. It has the electronic spark advance, and sure sounds like a winner to me. (Silversurfer - yes - there is a Brison twin. I just found that out also).

Edited: I just answered my question about prop size. The ZDZ80 states that this engine will swing a 28 x 8 prop.