My engine started backwards until I read a post like this which referred to over priming the engine; I used to flip the prop 4-6 times to prime it (enough to see fuel enter the carb, plus an extra flip or two). Now I prime until I see fuel ALMOST reach the carb, then try to start. One or two flips with the ignitor and my engine starts the right way. So my experiences is if your engine is running backwards it has too much fuel.