Small Engines (Lawn Mowers, etc.): Kohler Command 16 smoking, walbro carburetor, exmark mower

Question
I have a Kohler Command 16 engine on my Exmark mower which is three years old. Residential use only. Service for the first two years was done by the business I purchased it from. Last summer the compression on the first pull when cold was so high that I had to pull steady very hard until the compression released, after that I could pull like normal to start the engine. This summer the engine started to smoke very heavily on incline. I checked the oil level and it seemed high so just to be safe I drained and refilled with the appropriate amount. Worked great for 5 uses of 45 minutes each. After adjusting the mower bed this morning (engine at a 15-20 degree angle for 40 minutes) the engine smoked continually while in use. Checked the oil and it was very diluted and by gas. Drained this, changed oil, changed filter, changed plug and it still smokes but starts easily. Any ideas what's wrong?

Thanks

Answer
Do not run this engine until this is fixed.  The number one cause of the mid-size Kohler and Briggs engine rod failures is from the carburetor leaking gas into the crankcase.

Personally, if it were mine, I'd replace the carburetor.  You can try rebuilding it, but it will have to be cleaned thoroughly, spray cleaner will not do the job.  It will have to be soaked or cleaned ultra-sonically and even then we have about a 50% success rate with the Walbro carburetor.  We replace all the Nikki carburetors.

Let me know if you have any questions.  Thanks, PK