Small Engines (Lawn Mowers, etc.): BRIGGS 22HP V-TWIN INTEK MOD. 407777, gasket kit, valve seals

Question
DEAR SIR,
I HAVE A HUSKEE PRO GT 22/50. THIS PAST SEASON THE ENGINE STARTED MISSING AND PUFFING OUT BLACK AND GRAY SMOKE. I REMOVED THE PLUGS FOR INSPECTION AND FOUND THEM TO HAVE EXCESS CARBON BUILD UP ON THE ELECTRODES. I ASSUMED I HAD A HEAD AND/OR VALVE PROBLEM.I OBTAINED THE REPAIR MANUAL AND A COMPLETE GASKET KIT FROM BRIGGS.UPON REMOVING THE VALVE COVERS, EXCESS OIL WAS SITTING IN THE COVERS. THE COMBUSTION CHAMBER WAS WET AND HAD EXCESS CARBON ALSO. NO VISABLE CRACKS OR GASKET PROBLEMS.INTAKE VALVES APPEAR OK.EXHAUST VALVES APPEAR OVERHEATED WITH HEAVY CARBON.DOES THIS SOUND LIKE A SEAT/SEAL PROBLEM OR SHOULD I GO DEEPER?

Answer
Mike, sound to me it is sucking some oil, have you pulled a compression test in both cylinders? This is where I would start. If your running strong compression 150+ I would suspect head problems, worn valve guides and so forth. Might require new valves, seats ground,  valve seals, and springs. Also make sure your oil returns are not clogged under the valve covers in the heads. Either way must begin with a compression test........Tom