90403-ZW1-000 Plain (6MM) Washer - Overview. The 90403-ZW1-000 Plain (6MM) Washer is a fundamental component within Honda marine engine systems. It plays a crucial role in providing secure and reliable fastening for various assemblies in Honda marine and active marine equipment. Engineered precisely to meet factory specifications, this washer helps maintain system integrity and long-lasting performance.. Key Features. OEM genuine Honda part ensuring exact fit, form, and function.. Designed with