Bonjour,
After long hours of fruitless testing of this superb Hit and Miss engine, I understood why my engine wouldn't start: Fuel wasn't reaching the microcarburetor.
The fuel pump seems weak on my model.
I never see any fuel returning to the transparent return hose.
By creating a slight overpressure in the fuel tank by blowing into it with a flexible hose at start-up, I solved the problem, and here's the result
https://youtube.com/shorts/wyM4Ua-1a1AFor information, my model is #3