Oil Fuel mix ratio

[bmccuej]

I have recently obtained and would like to use a 1980 9.9 hp johnson sail master engine.

Does anyone know what the oil fuel ratio would be?

[deniseO30]

I recently sold one. They will run on 100 to 1 but most people use 50 to 1

[Gene T]

If I remember correctly you should run 50/1 if you run it hard, 100/1 is for idling like when you in trolling (fishing term). If you idle all the time the engine will run too rich at 50/1 so will run smoother at 100/1. So pushing a sail boat would require 50/1.

Gene

[mdbee]

Keep in mind there a various oils, with recommended mixture ratios from 20:1 all the way to 100:1

Your motor was probably designed for a 50:1 (my guess) Among other things, this means the carb was jetted for this ratio. Find an oil thats compatible for that ratio.

Originally Posted by bmccuej

I have recently obtained and would like to use a 1980 9.9 hp johnson sail master engine.

Does anyone know what the oil fuel ratio would be?

[casioqv]

I strongly disagree with the above posters, whom suggest running anything other than the factory recommendation of 50:1. Even if the motor is run lightly, less oil will significantly decrease engine longevity.

On the other hand, running more oil than recommended won't damage the motor but will cause excessive smoke and foul the spark plugs.

Stick with 50:1!

[casioqv]

Originally Posted by mdbee

Your motor was probably designed for a 50:1 (my guess) Among other things, this means the carb was jetted for this ratio. Find an oil thats compatible for that ratio.

I don't see how the carb jets are related to the oil ratio. AFAIK, the carb jets determine the air/fuel ratio which is something entirely different from the gasoline/oil ratio.

The carburetor will function at any oil ratio- but insufficient oil will cause accelerated wear on the bearings, pistons, and cylinders due to poor lubrication.

[bmccuej]

Awesome, I knew I could get answers posting on this site.......Thanks Much!!!!!

[carl762]

Yup, 50:1 and you're golden.

[pedcab]

Originally Posted by casioqv

On the other hand, running more oil than recommended won't damage the motor but will cause excessive smoke and foul the spark plugs.

Stick with 50:1!

And carbon build up in the cylinder head and pistons, and sludge build up in the exhaust, and more polution...

[mdbee]

Maybe thats because you haven't spent over 30 years selling motorcycles.

Originally Posted by casioqv

I don't see how the carb jets are related to the oil ratio. AFAIK, the carb jets determine the air/fuel ratio which is something entirely different from the gasoline/oil ratio.

The carburetor will function at any oil ratio- but insufficient oil will cause accelerated wear on the bearings, pistons, and cylinders due to poor lubrication.