Drain the tank, fill it with fresh gas, drain the carbs (pull them and pull the float bowls and take a look if your feeling ambitious), blow the cylinders out and make sure they are dry, 1/2 a teaspoon of trans fluid in each cylinder to bump the compression and seal the rings if they've been washed down with gas, make sure the battery is fully charged. Fully charged, not "it spins ok." Fully. Charged. Use a hydrometer and check the cells, add acid or distilled water. Better yet, go buy a new AGM battery, it prolly needs a battery anyway; and no sense fucking with a shitty old lead acid battery if you don't absolutely have to. Even with a new battery it wouldn't hurt to hook up a car battery with some jumper cables. Did I mention make sure the battery is fully charged? A new set of spark plus and you should be good to go. I said a new set, not they got fuel soaked and you cleaned them with brake cleaner, a new set.