You said you checked for spark. You did not say you have spark. Have you stuck a screwdriver in a plug wire, held it close top a ground and spun the engine to SEE the spark? Hell, I always just hold the screwdriver in my hand. It ain't gonna hurt you. Just give you a little jolt. Sounds to me like there's no spark. IF it is getting fuel.....even if it's out of time, you will get SOMETHING. whether it's a running engine or a pop through the exhaust or carb, if theres fuel AND fire, SOMETHING will happen.