I have a YS 80 in a Hirobo Freya and almost every flight ends with a flameout and a blown plug. Engine has about 30 minutes of run time, using 30% nitro and needles set rich, smokes like a chimney at hover and forward flight. Afraid to fly heli as last time it cost $400 to repair the damage caused by a plug failure at the wrong time. Using Enya #3 plugs.

It might be an issue with something else in the engine like a rod problem. It needs to be looked at by a service facility.