13621-ZY3-A01 T/B Drive Pulley - Overview. The 13621-ZY3-A01 T/B Drive Pulley is a critical part of Honda marine engine systems. It plays a vital role in the timing belt drive system, which transmits mechanical power from the engine to essential components, ensuring efficient engine operation and vessel propulsion. Designed for precise compatibility and high durability, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Genuine OEM