Kind of late to this one but what about the strength of the spark? I'm thinking maybe the spark is a tad weak. I'm thinking starting fluid is more volatile and helps with cranking when it is cold. Once the engine has some heat in it, it cranks better? Id finish the carb and choke checks as suggested first. Can you choke the engine enough to actually flood the plug when trying to crank it? Grasping at straws here
