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Oil mix ratio

H

Howiser

New member
I have a 1961 Evinrude 5.5 HP that does not idle well or start well after several starts and stops. I took out the spark plugs and found them oil fouled. I have been using a 24:1 mix ratio that someone told me is the correct one for that motor, but I think it is too much oil. What is the recommended ratio, 24:1, 50:1, or something in between?
 
Thanks for your quick reply. Your suggestion of 3 oz oil per gallon of gas calculates to a 42:1 ratio, which I was planning to try if I did not get any information. I have read that motors prior to 1964 require 24:1 ratio unless they have needle bearings instead of bushings. I am not positive if mine has needle bearings, but a parts break down shows liners and needles for the crankshaft, so think your suggestion should work and hopefully greatly improve performance.
 
I now have NGK-B6S as replacement for the original ones in the motor when I bought it, which were AC-M-42K. I have received various information to use 50:1 or 40:1 plus one person said to use 3oz per gallon of gas, which calculates to a ratio of 42.6. I started out using a 24:1 ratio, but it kept oil fouling the plugs, so I went to a 40:1 ratio and that seems to work good. I am still not sure what Evinrude recommends for this specific motor.
 
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