sanjoh, did you get the hub adaptor from CH Ignitions? I had wanted to put CH-Ign on a Cub Kadet 25cc, which is very similar to the Echo 25cc, but was told they didn't have a hub adaptor that will fit the drive shaft taper.

I really like the Echo engines. They may be a little expensive, but they are dual ringed, dual counter weighted and dual bearinged.