I can tell you this- I winterized with the top off and took the front hose of the exhaust manifold and Nothing came out-I then took the rear hose of the exhaust manifold off where it exits the bottom of the hull (Inside the Back of the hull) and about 3 table spoons of water came out of the hose. Next I took the top exhaust hose off the water box and there was about 12 ounces of water in the water box because it took 3-4 turkey baster siphons to get it out.My know-it-all old man of the sea Master Mariner's Ticket father-in-law says that 55psi air pushed through the flush port to evacuate any water from the exhaust is not good enough. Says you need to get anti-freeze in there as well.
My Spark manual says 55psi air should do the trick. Anyone doing this antifreeze jug higher than the spark with hose attached to flush inlet and run the engine thing?
I added about 12 ounces of antifreeze to the water box. NOW the water box holds about 2 gallons of liquid so if the small amount of water had frozen it just would have expanded slightly and would Not have been a problem.
Most old timers (Like me) remember the old 2 stroke days when Antifreeze through the engine and water box was mandatory because the engine was lake water cooled Not Sealed with antifreeze like our 4 strokes.