98066-56726 S/PLG (X20FSR-U) - Overview. The 98066-56726 S/PLG (X20FSR-U) is a genuine Honda spark plug designed for Honda marine engine systems. Its primary function is to provide consistent ignition performance, supporting the engine's combustion system to operate efficiently and reliably. As a critical component in the ignition system, this spark plug ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Genuine OEM Honda spark plug e