Small Engines (Lawn Mowers, etc.): Engine Overheating, plug gap, compression stroke

Question
My daughter's B&S tiller engine ran for about a minute when she noticed that the muffler was glowing hot and shut it off.  She said that it seemed to be running fast.  She had used the choke to start it but opened it after it started.  What is the likely cause of the hot muffler?

Answer
 Hello Glenn:

 1- Remove the Muffler and Check the Exhaust Port for Carbon Blockage. 2- Check the Muffler for Blockage. 3- The Wrong Spark Plug  4- Improper Plug Gap (.030in Gap) 5- High Speed Air Mixture Screw (Carburator)Too Lean. 6- Flywheel Key Damaged. **The Flywheel Key Times the Plug Fire to the Piston Location on Compression Stroke.** 7- Valve Lash needs to be Reset. 8- Exhaust Valve in the Process of Burning the Valve Seat. Send me the Model, Type and Code Numbers Off of the Engine, Please. With these Numbers I can Locate a Breakdown of the Engine and Better Assist you. Hope this Helps. Let me know what Happens, Please. I enjoy knowing the Outcome. Thanks.

 Good Luck

 Respectfully

 John