91316-ZV5-821 O-Ring (3.5X38.7) - Overview. The 91316-ZV5-821 O-Ring (3.5X38.7) is a crucial sealing component within Honda marine engine systems. This O-ring supports the fuel and hydraulic sealing systems by providing a reliable barrier against fluid leaks, ensuring the engine operates efficiently and without contamination. Manufactured to Honda's exact factory specifications, it seamlessly integrates with existing parts to maintain system integrity and optimal performance.. Key Features. Prec