51490-MFR-671 Fork Seal

51490-MFR-671 OEM Honda Goldwing GL1800 Left Side Fork Seal.

Fitment: Honda Goldwing GL1800 2112-2017

Specify genuine factory supplied fork oil seals and you will be fitting the very highest quality items that will be both easy to fit and enjoy long term durability - other makes of oil seal may be just as good, or they may not?
If you don't wish to go to the trouble of dropping the fork leg assemblies twice in a relatively short time, then fitting factory specified items would be the sensible course of action for long term results.