Yamaha - Throttle Body Air Intake & Fuel Control 6EM-13751-00-00. Overview. Throttle bodies are one of those components you really notice when they're not right-rough idle, hesitation, or just a motor that doesn't feel as responsive. After working on plenty of Yamaha setups, I've seen how a clean, properly functioning throttle body brings everything back into line. It controls how air moves into the engine, so it plays a big role in overall performance. When it's dialed in, throttle response fee