Has anyone built a Birdi AT-6? I bought one at a swap meet but it does not have any written instruction with it. It does have the full size plans so I should be able to go off that, but the plans do not give much detail on the retract installation. Also, I would like to know what people put in it for an engine. The plans show a .61 2 cycle, but I feel that I should put something bigger in. Any insight on this kit would be mush appreciated.