Small Engines (Lawn Mowers, etc.): tractor will not stay running, briggs and stratton, ohv engine

Question
My Briggs and Stratton 11.5 engine will not stay running.I spray either in it and runs for a few seconds. Runs for 10 minutes and dies. I have changes the plug and oil gas is fresh. Dont know what to do. Thanks

Answer
  Without knowing the model number, I will have to make some
guesses.  I am guessing that your engine will start and run fine for 10 minutes then die, then you will prime it with some ether, and
it will run a few seconds, then die, and will not start and stay running until it has cooled down, and this goes on the same way every time.

  It sounds like it is an OHV engine, and you need to adjust the
valves, if you can give me the model numbers, I can give you some better details.
Thanks,

Fish