I have a 3hp Yamaha two stroke with on-board fuel tank, and I store it in my dock box all summer. I close the fuel petcock and run the engine until it runs the carb out of fuel and then lay it on the side; according to my manual, I can only lay it on one side. For what it's worth, I also have a 15hp Johnson that I can store on either side, or even "vertically" laying down. I don't think it matters whether 2 or 4 stroke as far as how you can store it (which side), as much as it does specific design of the motor.