Confirm the assembly position before selecting the genuine Honda 16mm lock nut listed for a 1981 CB900C Custom. Its broad clutch and rotor description and supersession references need to be matched to the fitted component. It is an individual hardware purchase rather than a complete repair package.
Use the exact part reference and assembly position
The nut is identified as 90231-KCS-651 and sold individually. Compare the applicable parts diagram and removed hardware so its general clutch/rotor description is narrowed to the actual location being serviced.
Several earlier references are listed for this nut, but that list does not locate the part in your engine. Compare the actual clutch or rotor assembly with its service information before ordering. Changed engine components may require a different hardware application despite the motorcycle’s original identity.
Keep the repair scope specific
The product supplies one nut. Check mating threads and any associated locking pieces under the correct service procedure. Do not infer that every assembly described broadly as an oil-filter rotor exists in the same form on this motorcycle, or that the nut includes a service tool.
Buying questions
Is the part described as genuine Honda?
Yes, under reference 90231-KCS-651. Match that reference and the exact assembly location before selecting it for the repair.
Does the individual listing establish the total needed per motorcycle?
No. It is sold each, with one commonly required where used. Count the verified positions being serviced rather than converting that wording into a universal complete-bike quantity.
Is the 16mm description enough to select the nut?
No. The full reference and assembly position matter alongside size. A nominal dimension alone does not establish the thread, locking form or other requirements of a different fastener.
Vous ne savez pas quelle pièce choisir ?
Envoyez-nous le modèle et l’année de votre moto, des photos de la pièce actuelle et les détails de toute modification par rapport au montage d’origine.