The twin runs much smoother than the 30cc single. With it running in the plane, you can sit a glass of water on top! (SCRATCH THAT; a beer!!)
The test stand was so weathered and worn, the plywood was coming apart. That was the last run on it, then I built another. It was so wobbly that I shouldn't have used it that last time, but I was anxious to test run that engine and didn't want to stop to build a new stand.
AV8TOR