16400-ZW5-013 Throttle Body Assembly - Overview. The 16400-ZW5-013 throttle body assembly is a critical component in Honda marine engine systems. It regulates airflow to the engine, controlling engine speed and ensuring smooth acceleration and deceleration. Engineered for durability and precision, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Genuine OEM throttle body assembly designed specifically for Honda marine engines.. P