Well, I'm no expert but 40:1 mix will not hurt anything. At least for one tank. I'd keep a couple spare plugs on hand as the more oil you mix, the more likely you are to foul a plug.
What I would do is squirt a tablespoon of your 2 stroke oil straight into the cylinders via the spark plug holes. Re-install old plugs. With spark plug wires off, crank engine over a few seconds. This will lube upper end quite well. As for a tank of 40:1 mix, I wouldn't think you would have to do this. Buy some Seafoam from a local auto parts store and mix with your first tank of fuel. This will clean everything from bottom end to top end, and along with any carbon build-up.
Buy new spark plugs and double check that you have good blue spark on all cylinders. You should be good to go.
Hope this helps...
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Practice C-P-R. Catch, Photo, Release. The future of our fishing depends on it. St. Croix SCV Rods. The best!
get the OEM Evinrude manual, you have a hydro-electric shift motor. you need it to change the impeller, and understand how the shift works. 50:1 is correct.
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