Small Engines (Lawn Mowers, etc.): Honda 610 reengined grasshopper, grasshopper 618, valve adjustment

Question
Purchased an used grasshopper 618 with a new Honda gx610 twin vee engine and when mowing heavy grass engine stalls/dies after about 5 - 10 minutes mowing. It restarts fine, a little choke helps, and runs for a couple of minutes before stalling again.  In lite mowing no problems. Feels like it is staving for gas, Thanks for any ideas. Glenn

Answer
   It sounds like the valves might be adjusted a little tight, and
under heavier loads, the engine heats up more than light mowing,
and the valves expand more and you lose compression.
  After 5-10 minutes, the engine cools a little, enough to start
and run until the valves expand again, and so on.
     You will need to remove the valve covers and obtain some feeler gauges to check your valve adjustment, I will scrounge around and see if I can find some clearances online, but .005 on the intake
and .007 on the exhaust would probably be about right.