Small Engines (Lawn Mowers, etc.): Kohler model cv492 #27506, kohler gas in exhaust

Question
I have kohler cv492 engine on a craftsman lawn tractor.  When starting, gas runs out of the exhaust pipe.  Once started, it will run well for 15-20 minutes and then chokes down.  Removing load and reducing throttle to idle usually keeps engine running.  As choking down begins, black smoke is emitted from exhaust.  I would appreciate your thoughts about this and help in fixing the problem.

Thanks in advance for your help.
Mike

Answer
First, don't try and run the engine until this is fixed as you can very easily throw a rod.  The needle in the carburetor most likely isn't seating and the carburetor needs to be soaked in cleaner for an hour or more and rebuilt with a new carb kit.  I would change the oil as well as you may have a good bit of gas in the crankcase.  Also, if you haven't already, a new air filter is also called for.  Let me know if you have any questions.  Thanks, PK.