90203-ZY1-801 Lock (6mm) Nut - Overview. The 90203-ZY1-801 Lock (6mm) Nut is an essential fastening component designed specifically for Honda marine engine systems, functioning within the hardware category of marine rigging and accessories. This lock nut plays a critical role in securing key components to prevent loosening that could derive from engine vibrations and mechanical stresses. Engineered to meet factory specifications, the nut fits seamlessly into the system, maintaining the integrity