Small Engines (Lawn Mowers, etc.): Kohler 19 hp Courage - gas in oil, gravity fed, gas mixture

Question
After sitting for three weeks I went to start my 1.5 yr old Troy-Bilt mower with Kohler 19 hp Courage engine.  The gas tank was empty.  After adding a gallon it started fine and exhibited extreme smoking, and died on its own after about 30 seconds.  I restarted, same amount of smoke, so I shut it off.  I noticed some oil had dripped onto the ground from the muffler exhaust and became concerned.  I inspected the carburetor after removing the filter and found a lot of oil/gas mixture.  So I drained the oil and sure enough, it was very thin and very diluted with gasoline.  On this model tractor, the fuel tank is higher than the engine...if it gravity fed all the way into bottom of the engine while sitting, something must be wrong but I'm not sure what it would be.  Any idea what the problem is and how I should proceed?

Thansk for your help, please let me know if you need any further information.

Answer
Hello Brian,

I wonder if you have propped the machine up with the side (the one with the spark plug on it) UP.  This would cause the oil to run and possibly mix with the gasoline (as found in the carburetor).  Otherwise you can check that the oil level isn't too high.  Check that the angle of operation is not kept for too long a time at a severe angle.
Check to see if there is leaking or damaged seals, gaskets, o-rings.  Also check to see if the R.P.M. for that engine is correct.  Check carburetor setting for too lean a setting.  Check the engine compression with a compression tester.  And finally check the valve guide clearance for excessive wear.

As an aside, I don't believe that the position of the gas-tank in relation to the position of the engine is a factor.

Regards,
Howard