Yamaha - Throttle Body Air Intake & Fuel Control 6EK-13751-00-00. Overview. Throttle bodies are one of those parts you notice right away when something's off-hesitation, rough idle, or just not getting clean response when you push the throttle. I've worked on enough Yamaha setups to know how much this piece affects how the engine feels overall. It controls how air comes in, which ties directly into performance and efficiency. When it's right, everything feels smooth and predictable out on the wa