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1978 Honda CB400A Carburetor Service Components

Small carburetor parts can require very different orders on the 1978 Honda CB400A. The verified choices here are a float-bowl drain screw and an air cut-off valve assembly. Check the affected location and fitted carburetor before replacing parts or choosing quantities.

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Currently viewing Carb Floats & Other Carb Components

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Honda CB1100 CB1000 CB900 CB750 float bowl drain screw -a

Honda CB Stock Type Float Bowl Drain Screw ~-A

$6.50 USD
48-5042
Small part, but an important one. This float bowl drain screw with included O-ring allows you to properly drain the carburetor bowl without leaks,...
Honda CB1100 CB1000 CB900 CB750 float bowl drain screw

Honda CB Stock Type Float Bowl Drain Screw

$6.50 USD
48-5042
Replace your stock-type float bowl drain screw with this Float Bowl Drain Screw with O-Ring for the later DOHC and Nighthawk lineup.Note: sold each,...
Honda CB750 CB400 carb float 16013-679-005

1978-79 Honda CB750 / CB400 Carb Float ~ Replaces 16013-679-005

$29.95 USD
20-6506
Replace your 1979 DOHC CB750 or CB400 carb float with this Carb Float with Pin, replacing OEM #16013-679-005.4 carb floats are used per bike,...
Honda CB400 air cut off valve 16048-425-671

1978-79 Honda CB400 Air Cut Off Valve ~ Replaces 16048-425-671

$27.03 USD
20-4022
Replace your CB400's carb air cut-off valve with this Carb Air Cut-Off Valve, replacing OEM #16048-425-671 (diaphragm) plus spring and O-ring.Key Features• Carb air...
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1978 Honda CB400A · Carb Drain Screws & Air Valves Buying guide

Distinguish the bowl drain from the air cut-off valve

The drain screw is supplied individually with its O-ring. The air cut-off valve comes with a diaphragm, spring and O-ring. Choose between them by the repair location rather than their shared carburetor category.

Parts to consider

Honda CB Stock Type Float Bowl Drain Screw Float-bowl drain screw with O-ringStock-type drain screw supplied with an O-ring. Sold individually and listed for the CB400A.View part 1978-79 Honda CB400 Air Cut Off Valve ~ Replaces 16048-425-671 Carburetor air cut-off valveDiaphragm replacement for reference 16048-425-671, supplied with spring and O-ring.View part

A defined drain-screw purchase

The stock-type drain screw includes its own O-ring and is sold each. Inspect the bowl’s threaded and sealing areas when deciding what to buy. A replacement screw should be chosen against the fitted bowl, especially if the motorcycle no longer has its original carburetors.

Keep diaphragm service separate

The air cut-off valve package includes the diaphragm corresponding to reference 16048-425-671, plus its spring and O-ring. That is a different repair from renewing a bowl drain. Use the CB400A service information to identify the affected assembly before choosing replacement components.

Carb Drain Screws & Air Valves questions

Do I need to order a separate drain-screw O-ring?

The featured drain screw is supplied with an O-ring. It is sold individually, so order for the drain positions you intend to renew rather than assuming a pair is supplied.

What comes with the air cut-off valve?

The product specifies the diaphragm, spring and O-ring. Compare these with the fitted carburetor’s air cut-off assembly and confirm any additional worn hardware separately before starting the repair.

Will these parts fit replacement carburetors from another model?

That needs direct verification. The applications cover the 1978 CB400A, but a substituted carburetor can use different drain seats or diaphragm arrangements. Identify the fitted carburetor before ordering.

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