Hi Fred, it sounds as if the difference is a function of temperature. Things that change with temperature and could cause something like this are the tappet clearance (decreases when hot), vapour lock in the fuel line (could have been modified to bring it near cylinder or muffler), or a choke malfunction. How is the choke operated? If you have the Choke-A-Matic system, and you are putting the speed control in the "Start" position to restart it, you would be applying full choke to a hot engine, and it definitely wouldn't start. To get beyond those wild guesses, we'd need more information, in particular looking for modifications that have been made to the engine somewhere along the line.
