Small Engines (Lawn Mowers, etc.): Kohler CV-15 wont start when warm, hydraulic lifters, air vent

Question
Hello,

I have a Kohler CV-15 in a Simplicity rider.  When cold, it starts right up and runs well.  When warmed up, it is impossible to start.  I have taken the carb apart and cleaned thoroughly, and tried a new spark plug.  Spark is good and hot.
When it does this, it will backfire and maybe run slowly then stop.  I checked the plug, and it is dry not wet.  I am thinking the hydraulic lifters aren't pumping up.  My next test will be to change the oil and filter.  This wasn't mine, I just got it so I have no idea if it has 10W30 in it as it should.

Any help or ideas are appreciated.

Thanks,

Dave

Answer
Check your fuel line you might have one that's running close to the muffler where the exhaust manifold.  This would cause vapor locking when the engine got hot and the outside temperature is hot.  The next thing to check is the fuel cap air vent to be sure the tank is empty check the air cleaner to be sure it isn't dirty and do scheduled maintenance on the engine.  You should find your problem in this area.

Good luck on your project