The chart shows the best venturi diameter for balanced performance on an average engine of the given displacement. Check out my last vid for a more in-depth explanation! The best choice is also dependent on the use of the engine. Race bikes will often have even larger carbs because they prioritize peak HP. They also often have more valves per cylinder and other factors that increase flow efficiency. All of that will allow for a larger carb to be more effective. On the other hand street bikes and