RevZilla is proud to carry every original part available for your 1998 Yamaha WR400F OIL PUMP assembly. Simply reference the OEM parts diagram to confirm the exact part numbers you need. If the assembly calls for more than one of any given part number, it will be noted for you in the suggested order quantity so you can get exactly what you need to get the job done right, the first time. Not quite sure? Feel free to shoot us an email or give us a call to get hands-on help from an OEM parts expert.