I have a John Deere mower that will crank but not start. I have cleaned the carbs and checked the spark on the plug, both are good. I tried putting a small amount of fuel in the cylinder and all I got was a small back-fire. Any thoughts?

Hi,
Sounds like a Kohler engine with a sheared flywheel key.
Peace,
Clarke

My tractor had a similar problem I just lightly jump started it with my car. I don't know if that helps you.