Small Engines (Lawn Mowers, etc.): rough running kohler 17.5, spark plug gapping, combustion chamber

Question
my scott (john deer) mower was running fine, but all at once it started running rough, (backfiring & popping)and the muffler & header pipe started glowing red, got any ideas?
serial no. 3216800193
spec no. ps 27509

Answer
Dear Wayne,

Not sure of the engine model/serial no. but anyways, it seems you're having an overheating problem with this machine.  Check if there is too much load on engine, check to see if the oil level is correct, correct viscosity, Check if there's a cooling air flow - or obstructed or clogged fins, Check to see if the carb is correctly adjusted - with correct rpm settings, check for wrong spark plug [gapping] or ignition timing, Check for carbon is combustion chamber [or build-up] of carbon outside of chamber, check the flywheel for damage or wrong flywheel.

Once all these checks are found to be okay. Next I would check if the valves are sticking or seated improperly,  + improper Valve lash or weak valve springs.

Hopefully this will get you started on the road to a useable machine.

Howard