If you have to mix oil with the gas, you most likely have a 2 stroke (there are a few oil injected 2 strokes though) If you are SURE you don't have to mix oil with the gas, you have a 4 stroke.
honda ,im not 100 percent positive but i dont think merc ever made a 80 hp 4stroke,i think it was and is 75 then 90 or 115? the honda was a small hp motor at that time.