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  • Honda CB650 / CB550 / CB500 Cylinder Base Gasket ~ Replaces 12191-426-306
Honda CB650 CB550 CB500 cylinder base gasket 12191-426-306
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Honda CB650 CB550 CB500 cylinder base gasket 12191-426-306

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Honda CB650 / CB550 / CB500 Cylinder Base Gasket ~ Replaces 12191-426-306

18-6993
$18.50 USD
In stock Usually ships the same or next business day
Check model fitment View fitment
Questions about this part? Contact us 4.8/5 1,347 store reviews
Secure checkoutProtected payment
60-day returnsEligible unused parts Free ground shippingUSA & Canada over $50
Browse all parts
Honda CB650 / CB550 / CB500 Cylinder Base Gasket ~ Replaces 12191-426-306
$18.50 USD
Description

Replace your CB650 or CB500/CB550 cylinder base gasket with this Cylinder Base Gasket, replacing OEM #12191-426-306.

Key Features
• Cylinder base gasket
• Replaces OEM #12191-426-306
• Honda part name: Gasket, Cylinder
• Interchangeable with Honda 12191-374-000

Fitment / Compatibility

• Honda CB650 (1979‑82)
• CB650C (1980‑81) Custom
• CB650SC (1982) Nighthawk

• Honda CB500K (1971‑73)
• CB550K (1974‑78)
• CB550F (1975‑77) Supersport

Part Number: 18-6993

Read More
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Check the listed model and year, then read any fitment notes in the description.

Make Model Year
Honda CB650 1979
Honda CB650 1980
Honda CB650 1981
Honda CB650 1982
Honda CB650SC Nighthawk 1982
Honda CB650C Custom 1980
Honda CB650C Custom 1981
Honda CB550K0 1974
Honda CB550K1 1975
Honda CB550K2 1976
Honda CB550K3 1977
Honda CB550K4 1978
Honda CB550F1 1975
Honda CB550F2 1976
Honda CB550F3 1977
Honda CB500K0 1971
Honda CB500K1 1972
Honda CB500K2 1973

Free ground shipping over $50

To the USA & Canada. In-stock orders usually ship from our own warehouse the same or next business day.

Estimated ground delivery after your order ships
DestinationDelivery time
USA4–7 business days
Canada2–6 business days

Ground shipping includes tracking, emailed when your order ships. Need it sooner? Express options are available at checkout.

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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.

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Other shipping options

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 Honda CB engines use base gasket 18-6993?

It fits the listed CB500K and CB550 engines as well as the 1979-1982 CB650 family.

Which Honda cylinder-base gasket does 18-6993 replace?

One base gasket is included and cross-references Honda OEM 12191-426-306.

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.

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