Small Engine Troubleshooting Problems? Ask a Mechanic Now.
if you are getting backfire, the intake/exhaust valves are not working properly or carb is inserting too much fuel. I would try to clean out carb first. I am almost certain you have the Kohler Command engine with Hydro lifters and non adjustable valves. You can check the coil GAP and make sure it is correct. I would replace spark plug or at least check for dirty fouled plug. Let me know how all the above things are and if problem persists afterwards