Its like re-starting from cold. What happens is the fuel evaporates in the intake because of the heat soak of the engine once it is shut off. You see the engine actually heats up before it cools down. There is a kit you can buy that installs between the carbs and reed plate which is plastic. This stops heat transfer from the engine to carbs and it also comes with an extension for the return line. Its not easy to install if you have never pulled one of those engines apart before. If thats all to hard, pump the throttle about 10 times very quickly before trying to start it to prime it. The bogging is lack of fuel pressure. Make sure you wait for enough pressure before you go to take off. If you decide to do the job, clean the carbs whilst your there, theyre probably due.