I have a 1960 something mccolluch outboard that came with a boat I got, what oil/gas ratio should i run it at?

Question

The man I bought the boat said the motor called for 32:1, but he said to run it 25:1 unless it fouls the plugs, What should I do? Should I run the 32:1 or 25:1? The outboard hasn't been run for 2 years, but has been tuned up.

Answer 1

Recommended oil-fuel ratios vary from 16:1 to 50:1, depending on the model.  The forum in this link lists most of them:

http://forums.iboats.com/showthread.php?...

I won't try to list all the possibilities here.

Answer 2

Realx, you can run it with a ratio of 25:1 or 32:1

What the seller was doing was asking you to play safe in the gas to oil ratio. If your plugs are getting fouled then reduce the oil to gas ratio.

This is a 2 stroke engine you are talking about and needs oil in the gas for lubrication. Too little can cause your pistons to run dry and a possible engine seizure.

Since it has not been used for some time, run it for some time on a 25:1 ratio and then go on to a 30:1 ratio.

You can later check performance by opening your spark plugs and observing the colour inside. Oily Black - too much oil, white - too little oil, grey - correct mixture.

Please remember to use the correct grade and viscosity of oil as recommended by the manufacturer for best performance and increased engine life.

Need more info?

Answer 3

I suggest you mix the fuel at 50:1 Ratio!!!

If it's run at anything leaner your just asking for trouble. These old timers have a low primary compression and therefore require a  higher oil mixture, if the carburetor is set properly and have the right heat range spark plug there should be no problems with the engine fowling up. Just look at the mixture for the older Johnson Evinrude and Mercury engines all 50:1 mixture.