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Why does my 40 HP Evinrude smoke so much?

It has not run for 5 years, I just got the boat and last Saturday I started it up and runs good. Its a 1968 engine. I mixed the oil to spec's, 1 to 24, it says 1 qt of oil to six gallons of gas. So do you think it will stop smoking after I get some hours on it? Could I cut down on the amount of oil in the mix? Is there a better oil than the two stroke boat oil that I bought at the parts store? Thanks to anyone who answers.

Public Comments

1. OMC issued a service bulletin changing most of the 60's motors to 50:1, but don't change until you get confirmation from a trusted source. But any 2-stroke will smoke -- more on a cold morning, and less after the engine warms up. You need to use "TCW3" certified oil -- it's made for water-cooled engines which run at different combustion temps than air-cooled weedeater/chainsaw/whatever motors. I use walmarts "supertech" brand in my '79 vintage. After sitting for 5 years, the carbs will be pretty darned dirty. If you haven't put the boat in the water yet, don't be surprised if it bogs down when you accelerate. Gasoline leaves a varnish behind when it evaporates, and the high speed jets get too clogged to run. Were it mine, I'd rebuild the carbs before running it again. Couple hours and $30 or so well spent. Also, the water pump impeller will take on a "set", and it'll be way less effective -- or worse, dry rot might've set in. You don't want a fragment of neoprene rubber breaking off & clogging up your water jacket -- it'll turn a fine old motor into an anchor in no time.
2. Hello Duster, .......Judging from the age of the motor, I would say that smoking is normal. The oil to gas mix sounds about right, Some of the older outboards had 25 to one, some 30 to one, and a little later, 40 to one. Also, some four cycle motors were made. It sounds like you have a beautiful classic there. Many modern two-cycle engines have a second tank for the oil, and it is mixed automatically in the right ratio by a special pump. You should NOT cut down on the amount of oil that you use. You might look into a marina or boat shop for a less smoke oil to use, but it probably won't make much difference. .......When that motor was manufactured, there was a lot less concern about pollution than there is now. All two stroke motors would give out clouds of blue-gray smoke. You may find some locations which will not allow you to use the motor for that reason. A good trolling motor (Electric, of course) will push your boat with (almost) no pollution (but not very fast). .......Always, and I do mean ALWAYS, carry a tool kit with you in your boat. It should have two sets of spark plugs, a spark plug wrench, screw drivers (slot and Phillips) Extra cotter keys, everything necessary to remove the propeller, Pliers any anything else you can think of. Motors in that age had a tendency for the plugs to foul at the worst possible time (when you are up the creek without a paddle). Also, you may hit the smallest little stick in the water and the sheer pin (cotter key) sheers off allowing the propeller to spin free. The nut that holds the propeller on---it is good to have a spare (what was that "splush sound"?) .......When you store your motor for a long period of time, have the gas tank empty. A four stroke has the tank full. About every three years or so you may need to take the carb apart and clean out the "varnish" that builds up. It is from the oil in gas, it hardens up like oil in an artiest' oil paint. .....You might try putting in new spark plugs, to reduce the smoke. Also, when you start up the engine, the lower part should be in water. A forty HP motor is probably not air cooled. I used to use 55 gallon barrel for that purpose. If you have used it in salt water, you need to flush it out. Sea water is HELL on outboard motors.
3. Couldsnt be thats its ready for the JUNK MILL.
4. It sound like you got "lawnmower" 2 cycle oil, which always say's it's for outboards, but it's a heaver oil and doesn't mix or "atomise" as it goes through the carburetor. jtexas is correct in his recommendations, and you should go to 50:1 because you have roller bearings not bushings on the crankshaft. I'm always concerned with engines that haven't run in years. I'd bet the old owner ran the fuel out of the engine after each use, otherwise it probably wouldn't even start. Be sure to replace the water pump impeller now, jtexas is right, and you don't want to damage the motor. Remember this is a forth year old engine. Take it easy on it, but I've seen a lot of these motors in use. Good Luck!
5. You did not indicate the color of the smoke. Black Smoke indicates unburned particles of carbon from the fuel are blowing out the exhaust Blue Smoke comes from burning oil, If the smoke is blue cut down to a 1:20 mix and see if that fixes the issue White smoke is caused by water vapor in the exaust or unburned but atomized fuel
6. JTEXAS is absolutely correct....your mix is too rich.