Small Engines (Lawn Mowers, etc.): Techumseh 6.5 hp (Idel Problems, head bolts, cart motor

Question
Sir,

I am at wits end with a neighbor's go-cart motor. I try to help out the neighbors with help with their small motors, but I have a problem that I can not find the problem. I have cleaned rebuilt the carb. Cleaned the spark plug. The motor idles fine and for some reason about 3-4 mionutes iof idle it will die. Thought it might me a stuck float, but that does not seem to be it. After it is riden, it will die after a small time at idle. Have adjusted the idle up to the verge of engaging the wheels. I am at a loss, any advice would be greatly appreciated.

Answer
What is the idle rpm set to?
Have you checked the head gasket?

I once had a similar problem with a Tecumseh and eventually found 3 slighty loose head bolts on the exhaust side of the head.  Torqued all the head bolts to 200 inch pounds and it solved the problem.

Let me know what you find.
Eric