Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
This is the older flat head design engine. Have you checked the valves for clearance? It has to have some, .006 in is the gap. But it will work ok, as long as it is not zero. To get to the valves and tappets, you have to remove the intake manifold, t get the crankcase vent cover off of both sides.
Ok, may not be valves, run cylinder test and see if it is related to one cylinder. Loosen the spark plug wires,and with engine idling, remove one wire at a time. If engine dies when one wire is removed, the opposite cylinder is not firing. Run compression test, to see if a valve is stuck open.