Kawasaki rotary discs

When I was a kid I owned an example of this advanced engineering. Good power but the carb stuck out the right side- way out- and was covered by an aluminum eggshell case. A crash on the right side broke the case- $45, the engine inhaled sand, gravel and whatever else was on the ground so that broke the rotary disc- $15, a piston- $15 and rings- $15. Compare that to a Honda 90 piston $4.80, rings $2.40 at the time. 
I repaired it two or three times and gave up. When a kid was getting a few dollars a week for allowance, it was just not possible.