Small Engines (Lawn Mowers, etc.): Craftsman II riding smokes, riding lawn mower, crank case

Question
I have an older craftsman II 12hp (briggs engine)riding lawn mower and just changed the oil in it.  After mowing 1/2 my yard it started to smoke (black) out of the crank case and appeared to be very hot and then died.  It will start back up but be very sluggish and eventually smoke.  Any ideas on what may be wrong?  I don't have an owners manual, could I have put too much or too little oil in it?  I put one quart in and it showed to be at the correct level on the dipstick.  Thanks for your time!

Answer
Black smoke = to much fuel. Every time.  You probably have a carb leaking over.  This engine holds 48oz. of oil.  Or until the dipstick says it's full.

The engine will run until the fuel leaking through the carb finally fouls the plugs.  Look at the plugs. Are they a powdery black.  If so you know the carb is leaking and will have to be rebuilt.