Small Engines (Lawn Mowers, etc.): Engine stops when hot, defective coil, safety switches

Question
I have a Honda (GX610) v twin 18 hp engine which stops running after about 20 minutes.  If I wait a few minutes it will start again and run for about 5 minutes and stop again.
The engine is clean and full of oil.
Could there be a high temperature shut-down sensor gone bad or a coil?  

Answer
You are on the right track.  It is likely something like a shutdown or a defective coil causing this to happen.  If equipped, you need to bypass any safety switches that can shut the engine down (oil level, temp, etc.) and see if the problem is resolved...then replace that switch or determine the cause.  If this has no effect, try checking for spark immediately after the engine quits.  A healthy ignition system should be able to produce a strong enough spark to jump a 1/8" gap.  Hope this helps.