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1978 Honda CB400A Intake-manifold O-rings

The intake-related item here is the manifold-to-cylinder-head O-ring set for the 1978 Honda CB400A. The pack contains four rings. Match the joint and existing manifolds first, then order for the sealing work needed without treating the pack as replacement intake boots.

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Honda CB450 CB400 cylinder head intake boot o-rings (set 4) 91301-371-005

1978-86 Honda CB450 / CB400 Cylinder Head Intake Boot O-Rings (Set/4) ~ Replaces 91301-371-005

$8.19 USD
48-5044
Replace your cylinder head intake boot O-rings with this Cylinder Head Intake Boot O-Rings Set of 4, size 40 x 2.6mm. Replaces OEM #91301-371-005...
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1978 Honda CB400A · Intake-manifold O-rings Buying guide

Match the O-ring to the manifold-to-head joint

These 40 × 2.6 mm O-rings are listed for the CB400A and references 91301-371-005 and 91325-413-830. The pack quantity is four; determine the installed requirement from the actual intake assembly.

Parts to consider

1978-86 Honda CB450 / CB400 Cylinder Head Intake Boot O-Rings (Set/4) ~ Replaces 91301-371-005 Intake-manifold O-rings, set of four40 × 2.6 mm O-rings for the manifold-to-cylinder-head joint. Supplied as a four-piece set.View part

Order the seals for the correct end

The O-rings fit where the intake manifolds attach to the cylinder head. Airbox connections are a different location. Check which joint is being opened or repaired before buying, especially where replacement manifolds or a modified intake have changed the original arrangement.

Keep pack quantity separate from installed quantity

Each set contains four O-rings. The product’s general note says most applications use two, but your order should follow the fitted assembly and the positions being serviced. Do not assume that buying four rings means all four must be installed on the motorcycle.

Intake-manifold O-rings questions

Which size and references identify these O-rings?

The set is specified at 40 × 2.6 mm, replacing references 91301-371-005 and 91325-413-830. Compare the required manifold-to-head seal with those details before ordering for a changed intake.

Are these for the airbox end of the intake?

They are specified for the manifold-to-cylinder-head joints. Identify the leaking or dismantled joint before ordering; an airbox-side connection requires its own matching part.

Should I buy another pack to seal both intake positions?

First compare the required seals with the four rings supplied. Count the positions being serviced and confirm the size rather than ordering extra packs from the number of carburetors alone.

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