About the only way to know if that motor is good is to put it on a boat and run a sea trial for starting, idle, mid-range and wide open(maximum RPM)....otherwise it's just the "pig in a poke"....I've owned 4 Yamahas, a 4HP, 40HP, 115HP and for the last 15 years a 90HP.....and they've all been great....can't say first hand about the F50....
