51427-230-300 Washer (6x11) - Overview. The 51427-230-300 Washer (6x11) is a genuine Honda marine parts component designed to support critical marine engine systems by providing a durable and precise connection interface. This OEM washer plays an essential role in distributing load and preventing damage between mating parts within Honda marine engine assemblies such as Swivel Case & Mount Frame for BF5A2 and BF5A4 models. Made to exact factory dimensions with a 6mm inner diameter and 11mm outer