Rotax are getting out of 2 strokes for Planes. I lot of the reliability is in the hands of the Operator. When they were more universal, I've seen some engines I wouldn't run as a Lawnmower,, still being flown. Little compression and rattly when pulled over. Now they are pretty RARE and there's not a lot of Real Knowledge about them. Even your off road trail BIKES NEED REGULAR SERVICING to ensure a trouble free ride. I've never had a 2 stroke even falter but I'm Very careful WHOSE planes I will fly. I will fly something a bit suss ( do a test) if there's Paddocks all around and no trees to have to climb over. Nev