Small Engines (Lawn Mowers, etc.): green machine 4000 brush cutter, spark arrestor, exhaust port

Question
i have a an early 80's green machine 4000 37.4 cc engine that loses power and dies out when it heats up and i give it throttle.   any idea what it might be?  

Answer
 Hello Patrick:

 Remove the Muffler and Inspect the Exhaust Port for Blockage. You can Also Look at the Inside of the Cylinder and See if it is Scratched or Looks Smooth like Glass. You can Also see the Rings. Check the Muffler and the Spark Arrestor Screen for Blockage Also. the Spark Arrestor Screen is in the Muffler. If the Exhaust Port, Muffler and Spark Arrestor Screen are Clear, then the Rings May be Worn Out and Cant Expand As Far as the Cylinder to Maintain Compression. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John