I use a mix of gasoline, Seafoam, and 2 cycle premix oil to winterize everything I own that runs on gas. I mix it in an outboard motor tank, and when whatever I am winterizing starts smoking it's through everything and that's it. Prior to this I'd tried draining everything and fogging and still had problems. The idle circuits in some carbs are so small they can still retain fuel and gum up when drained. If you are storing in an area where things can get hot/cold/moist/dry, then I'd dump a couple caps full of automatic trans fluid into the cylinder turn it over slowly and leave it at TDC on the compression stroke. Plug exhaust and intake/carb as necessary to keep rodents and insects out.