Starting an engine after sooo long. (1) clean out fuel tanks, replace any gas with some fresh, new gas. Also ceck the oil, and change it. Even if it is clear now, there could be water from condensation. (2) pull carb and clean out. Spray with carb cleaner and blow them out with compressed air. Ensure all those tiny passages are clear of gum. Then reinstall the carb. (3) remove plugs and introduce penetrating oil into the cylinders. Let it soak a bit. Wiggle the crank by hand at first to see if the rings are free. Slowly try to turn it a full turn without force so you don't break a ring. (4) if it turns over by hand, leave the plugs out and check for spark. Ensure it has ignition. (5) now put the plugs in and try cranking it from the key/switch. Prime the carb with a splash of gas to see if it fires. Do not race the engine right off, let it idle a bit