Sorry about a second post but I wanted to say more. It is a common misconception that a 4 stroke engine will always spin less RPM than a 2 stroke. In airplanes, for the time being that is probably true. The same was true just 5 years ago in motorcycles. Now days a CR250 Honda 2 stroke engine will have a peak RPM at about 9700. It has a powerband that is useable only from about 7000 to 9000. A CR450, (the 250 main competetor) has a peak RPM of 11900. And a usable powerband from about 4500 to 11000. They both make approximately the same horsepower, 53. With the difference in breath of powerband it becomes easy to see why the 4 stroke is much perferred. The same technology is happening in airplane engines. So they will turn more RPM than 2 strokes and have a much more greater usable powerband. That will be the kiss of death to the 2 stroke engine. But that's ok. It has had a long and great life.
Thanks,
Barry