I would start by increasing the volume of fuel to the engine. Do this by using the larger fuel line. You will also need to get the next size up brass tubing for the tank. The stopper and back plate can be drilled out in the tank. I also drilled out my clunk and removed and drilled out the nipple on the carb. Mine was not leaning out but these things increased the performance and reliability of my engine. BTW I run Byron ST fuel an OS "F" plug a Zinger Pro Series 18x6 prop and a Bisson Pitts style muffler.


David