Alan, I read about that Honda engine also. It was an experiment to see if they could flow the same amount of air with a V Twin as they do with a V-4. So, they used 2 BIG oval shaped pistons with 2 rods per piston and 8 valves over each piston. I could see where the thing would Fly if they ever got the rings to seal.
The Scotch Yoke type crank I used is the main draw back to making HP with this little motor.