I have an old .46 enya 4stroke (which is a 52 now days) on my 4 star 40, and I love it, I'm turning a 12-6 prop on it. works great, I have several 4 strokes and I run 15% 2 stroke fuel in them, 2 stroke fuel has more oil than 4 stroke fuel, it works fine for me. and I can use one fuel to fly everything, good luck