What else has been done beside replacing the ignition?
Have you been inside the engine??
Loose connecting rod cap?
Rod hitting something?
Flyweight on camshaft hitting something?
When you turn the engine by hand, do you hear or feel anything rubbing?
Is the hub of the flywheel cracked at the keyway? (Visible from inside of flywheel.)
Piston hitting cylinder head?
Carbon build-up on top of piston?
Engine was rebuilt with new piston, rings, connecting rod, and crankshaft with bearings. I purchased the correct connecting rod off of ebay but the engine builder mentioned it looked slightly different than what was replaced and required some machining. The key and keyway for the flywheel are in perfect condition, the flywheel is definitely on tight. No carbon build up. When i rotate the engine by hand, no abnormal noises are heard or felt. I can hear the valves lift and lower. No carbon build up in the engine. I ran the engine at what appeared to be lean as it was running hot for a total of about 2 hours. Incorrect coil was used for the Overnight Solutions HET module. Carb was sent to Bolens 1000 and verified operating proper. New O.S. HET module and the correct coil connected. Good gas and verified spark plug ignites at exactly the the timing mark on the flywheel. I may see if the engine builder would be willing to check the engine and see if something is wrong internally.