About the Honda CB450K DOHC Twin
A 1970 registration or a 35 mm fork tube does not choose between the two CB450K seal profiles.
Combine the frame checkpoint with the removed seal
Sudco’s CB450K3 application chart splits the fork entries at frames 4017271 and 4017272. Its dimension chart maps them to 35 × 46 × 11 mm and 35 × 48 × 11 mm respectively. The table keeps those supplier references separate from the PartsNMore product labels. The OEM references and aftermarket profiles have not been fully reconciled; a frame number alone is not an ordering confirmation.
Keep engine and carburetor year gaps visible
The standard carb kits split at 1971/1972. The engine gasket set lists 1968–1974, while the individual friction and steel plates list 1966 and 1968–1974, omitting 1967. A broader carb-kit application does not extend either the gasket or clutch listing.
Parts and model differencesCB450K3 fork seals: frame checkpoint and physical comparison
| Sudco original-fork entry | PartsNMore option to compare | Required physical check |
|---|---|---|
| K3 through frame 4017271: 35 × 46 × 11 mm | Two 35 × 46 × 11 mm oil seals; store years 1968–1970; listing reference 91255-292-003. | Confirm 46 mm outside diameter, full height and the fitted fork. |
| K3 from frame 4017272 / K4: 35 × 48 × 11 mm | Two seals labelled 35 × 48 × 10.5/11 mm; store years 1970–1974. | Confirm 48 mm outside diameter, height/profile and retention arrangement. |
| Changed or unidentified forks | Frame checkpoint cannot identify the installed front end. | Use fork markings and removed-seal ID × OD × height; resolve any profile mismatch before ordering. |
References: Sudco applications and seal dimensions. These are comparison checkpoints, not a confirmed OEM-to-aftermarket interchange table.
Identify your motorcycle before orderingCB450K identification checklist
- Record the full K designation and frame number; photograph the fitted fork and removed seal markings.
- Compare outside diameter as well as height/profile and the retaining arrangement before selecting a 1970 seal option.
- For the carb kits, photograph both carburetor markings and compare standard 1968–1971, standard 1972–1974 or premium 1965–1974 package contents.