91301-MJ0-003 O-Ring (7.8X1.9) - Overview. The 91301-MJ0-003 O-Ring (7.8X1.9) is a precision-engineered sealing component supporting Honda marine engine systems. It plays a critical role in creating watertight seals and preventing leaks in fuel and oil systems, ensuring seamless operation and protection of engine components. Designed to exact Honda factory specifications, this O-ring integrates cleanly with existing parts, maintaining optimal performance and durability.. Key Features. 7.8 mm out