I would not condem an engine unless its mine and I can prove it.
I still say DA50, there is a guy at my field with the ZDZ 50 and it runs like crap, but it might just be his engine because I've flown planes with the 80 on it and they are a powerhouse. Gas engines will also be cheaper to feed
You cant condem an engine in someone elses plane. Was the ZDZ 50 timing right, fuel clean, carb adjusted???????
I have a ZDZ 50, it starts, runs, idle and transition to full power flawlessly. Weighing 3.37 lbs with ignition and cranking out 5.7 hp, swinging a 22X10 prop over 7000 RPM you tell me of a better 50cc engine.
This engine is going into a H9 Edge 540.