it uses 87 octane
if a 2 stroke motor you need to mix 1 pint of oil to 6 gallons of gas
That's the motor, which burns fuel and propels the boat.
Most all models of Yamaha outboards can be operated on a 50:1 fuel to oil ratio.
50/1
I rented a John boat with a 15hp Yamaha several years ago. The fuel consumption rate was about one gallon per hour at wide open throttle.
cut of fuel supply
straight fuel/4 stroke
Most likely need to clean carbs and check fuel bulb sounds like it is starving for fuel at higher rpm's also check spark plugs and clean them
Mixing ratio should be 50:1
dirty fuel injectors
50:1
50:1
oil ratio is 1% Pierre