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  • Honda CB750 / CB650 / CB450 Carb Pump Diaphragm ~ Replaces 16021-393-004
Honda CB750 CB650 CB450 carb pump diaphragm 16021-393-004
Carburetor pump diaphragm parts fiche diagram, SKU 20-9040, highlighted reference 9
Honda CB750 CB450 CM450 XL500 Carb Pump Diaphragm - Replaces Honda OEM 16021-393-004 — 02-rear (20-9040)
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Honda CB750 CB650 CB450 carb pump diaphragm 16021-393-004

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Load image into Gallery viewer, Honda CB750 CB650 CB450 carb pump diaphragm 16021-393-004
Load image into Gallery viewer, Carburetor pump diaphragm parts fiche diagram, SKU 20-9040, highlighted reference 9
Load image into Gallery viewer, Honda CB750 CB450 CM450 XL500 Carb Pump Diaphragm - Replaces Honda OEM 16021-393-004 — 02-rear (20-9040)
5.0 ( 1 review)

Honda CB750 / CB650 / CB450 Carb Pump Diaphragm ~ Replaces 16021-393-004

20-9040
$27.95 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 1,331 store reviews
Secure checkoutProtected payment
60-day returnsEligible unused parts Free ground shippingUSA & Canada over $50
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1 product reviews

Honda CB750 / CB650 / CB450 Carb Pump Diaphragm ~ Replaces 16021-393-004

Honda CB750 / CB650 / CB450 Carb Pump Diaphragm ~ Replaces 16021-393-004
$27.95 USD
Description

Rebuild your Keihin carb's accelerator pump with this Carb Pump Diaphragm, replacing OEM #16021-393-004 / #16021-393-014 / #16021-MC9-771. Kit contains 1 diaphragm with rod and 1 bellow rubber.

Note: for CB650 fitment, only fits if your bike requires an 89mm end-to-end pin. Check your pin length on the old diaphragm before ordering.

Key Features
• Carb pump diaphragm for Keihin carbs
• Replaces OEM #16021-393-004 / -014 / -MC9-771
• Includes diaphragm with rod + bellow rubber
• Honda part name: Diaphragm Set, Pump

Fitment / Compatibility

• Honda CB750K (1977‑78)
• CB750F (1977‑78) Supersport
• CB750A (1976‑78) Hondamatic

• Honda CB650 (1979 / 1981‑82), only if 89mm pin
• CB650C (1981) Custom, only if 89mm pin
• CB650SC (1982) Nighthawk, only if 89mm pin

• Honda CB450SC (1983 / 1985‑86) Nighthawk

Part Number: 20-9040

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

Make Model Year
Honda CB750A Hondamatic 1976
Honda CB750K 1977
Honda CB750F 1977
Honda CB750A 1977
Honda CB750K 1978
Honda CB750F 1978
Honda CB750A 1978
Honda CB650 1979
Honda CB650 1981
Honda CB650 1982
Honda CB650SC Nighthawk 1982
Honda CB650C Custom 1981
Honda CB450SCD Nighthawk 1983
Honda CB450SCF Nighthawk 1985
Honda CB450SCG Nighthawk 1986

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

What is included with the Keihin carburetor pump diaphragm?

The accelerator-pump kit includes one diaphragm with rod and one bellows rubber.

What must be measured before using this pump diaphragm on a Honda CB650?

The original diaphragm pin must measure 89mm from end to end for the specified CB650 applications.

Which Honda OEM numbers does the pump diaphragm replace?

The pump diaphragm replaces Honda OEM numbers 16021-393-004, 16021-393-014 and 16021-MC9-771.

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