Replace your DOHC CB's cylinder base gasket with this Athena Premium Quality Cylinder Base Gasket, replacing OEM #12191-425-306.
Key Features
• Athena premium cylinder base gasket
• Replaces OEM #12191-425-306
• Top-quality ISO-9000 approved
• Honda part name: Gasket, Cylinder
• Interchangeable with Honda 12191-425-000
Fitment / Compatibility
• Honda CB750K (1979‑82)
• CB750F (1979‑82) Supersport
• CB750L (1979) Limited Edition
• CB750C (1980‑82) Custom
• Honda CB750SC (1982‑83) Nighthawk
• Honda CB900C (1980‑82) Custom
• CB900F (1981‑82) Supersport
Part Number: 18-6991
Check the listed model and year, then read any fitment notes in the description.
| Make | Model | Year |
|---|---|---|
| Honda | CB750K Standard | 1979 |
| Honda | CB750F Supersport | 1979 |
| Honda | CB750L Limited | 1979 |
| Honda | CB750K | 1980 |
| Honda | CB750F | 1980 |
| Honda | CB750C Custom | 1980 |
| Honda | CB750K | 1981 |
| Honda | CB750F | 1981 |
| Honda | CB750C | 1981 |
| Honda | CB750K | 1982 |
| Honda | CB750F | 1982 |
| Honda | CB750C | 1982 |
| Honda | CB750SC Nighthawk | 1982 |
| Honda | CB750SC | 1983 |
| Honda | CB900C Custom | 1980 |
| Honda | CB900C | 1981 |
| Honda | CB900F Supersport | 1981 |
| Honda | CB900C | 1982 |
| Honda | CB900F | 1982 |
No listed models match your search.
Free ground shipping over $50
To the USA & Canada. In-stock orders usually ship from our own warehouse the same or next business day.
| Destination | Delivery time |
|---|---|
| USA | 4–7 business days |
| Canada | 2–6 business days |
Ground shipping includes tracking, emailed when your order ships. Need it sooner? Express options are available at checkout.
60-day returns on eligible parts
No restocking fees. Eligible parts must be unused, uninstalled, unaltered and complete. The 60-day window starts when your order is delivered.
Electrical parts are excluded from standard returns. Check return eligibility.
Start your return below. Wait for our instructions before mailing a part back.
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Canada Post Economy: Available at checkout for select small items. Allow 1–3 weeks for delivery. No tracking or insurance is included.
Outside the USA & Canada: Delivery times vary by destination and shipping method. Buyers are responsible for applicable duties, taxes and import fees. We cannot mark orders as gifts.
Frequently Asked Questions
Which DOHC Honda CB engines use Athena base gasket 18-6991?
It fits the listed 1979-1983 CB750 and 1980-1982 CB900 engines and is the premium Athena-brand option.
Which Honda cylinder-base gasket does 18-6991 replace?
One base gasket is included and cross-references Honda OEM 12191-425-306.
Where does the cylinder-base gasket seal?
It seals the joint between the cylinder block and crankcase; the cylinder-head gasket above the block is separate.