A 1988 model, 85 hp Force outboard requires a 50:1 ratio, one pint of 2 cycle oil, to six gallons of fuel.
I think you mean 2 cycle and it is 50-1
50:1
85hp
50:1 16oz per 6gal tank
You have a 718cc engine and your horsepower is 85HP
50:1 /16Oz.per 6 Gals. gas. I have the same outboard.
The year of the motor is 1985? Then it is not a Mercury Force. Also with the plugs that it takes, there is no gap adjustment,
The correct ratio for 1991 85hp Yamaha is 1:50. 1 liter of oil for 50 liters of fuel.
The 1938 (81A)730B was powered by a 85hp V-8. (82A) models had a 60hp V-8 engine.
The dry weight of an 85hp Yamaha outboard is 245lbs.
The year model of an Evinrude outboard engine is determined from the engine "model number", rather than the serial number.
you can try 25-1, if it's too smokey, work your way up to 50-1