Re: 1974 70 hp Evinrude long shaft running slow
At a minimum you should clean the carbs, replace the water pump impeller and spark plugs BEFORE you ever try to run it in the water if it has set up for that long. I'd bet the impeller has cracked and dry rotted and will shear a vane which could clog up the cooling system, resulting in a fried powerhead.
Likely it's got old fuel that has varnished in the carb float bowls and jets and it creating a restriction. If you run a cylinder lean due to these restrictions, you'll score a cylinder and be up for a rebuild in short time. 2 strokes don't like to be run low on fuel since they rely on that mixture to lubricate the cylinder walls.
