Intake Manifold | Honda CB450 / CL450 / CB500T
The rubber intake manifolds on a 450 twin go hard and crack with age, and once they do, the carbs pull in air the engine was never jetted for. These Japanese-made replacements restore the seal your tuning depends on.
Why You Need This
These bikes run constant-vacuum carburetors, which meter fuel off the vacuum signal in the intake tract. A cracked or hardened manifold leaks air right where that signal lives, so the mixture leans out and tuning turns into a moving target. Fresh, pliable manifolds seal the carb to the head the way the system was designed to work.
You'll hear this part called a lot of names: intake manifold, carburetor boot, carb insulator, isolator, intake pipe, carburetor holder, or carburetor flange. Same part. Ours are sourced directly from Japan, and each manifold ships with its own gasket.
Specifications
| Spec | Detail |
|---|
| Replaces OEM Part | 16211-283-000, 16229-283-306, 16229-283-010 |
| Fits Models | CB450 K0-K7 (1965-1974), CL450 K0-K6 (1967-1974), CB500T (1975-1976) |
| Material | Rubber (Japanese-made) |
| Sold As | Sold Individually — two per bike; one gasket included with each |
Note: The factory setup supports the carburetors at both ends — the manifold holds one side and the factory air filter boot supports the other. If you run pod filters, plan on adding a support to carry the carb weight so it doesn't hang entirely on the manifolds.
Model-Specific Notes
- CB350 / CL350 / SL350 K0: The 350 twins use their own manifold — get it here.
- SL350 K1-K2: These use a different manifold from the K0 — we stock that one too.
- CB360 / CL360 / CJ360: Different manifold as well — here's the 360 version.
- CB500K / CB550 fours: The CB500K / CB550 fours use different carburetor intake boots — this is the 450 twin / CB500T part.
Installation
Difficulty: Intermediate
Seat the carbs fully. The carb-to-manifold engagement on these bikes is shallow, which is why the manifolds need to be new and pliable — a hardened boot barely grips the carburetor at all, and the carb can work its way out while you ride.
Set the clamp edge flush with the edge of the manifold rubber. That puts the clamp's bite on the full engagement area instead of half of it.
Running pod filters? Fabricate a hanging support — zip ties, safety wire, or a small bracket — so the carburetor's weight rides on the support instead of the manifold.
Reusing the factory airbox? The original rubber boots from the air boxes can be stubborn to fit — a heat gun softens them up.
Our CB450 pod filter install video covers getting these manifolds seated, clamped, and supported — the same fundamentals apply whether you run pods or the stock airbox.
Frequently Asked Questions
How many do I need, and are gaskets included?
Two per bike, one for each carburetor. They're sold individually, and each manifold ships with its own gasket.
My carburetors keep working loose or falling off. What's wrong?
That's the classic 450 combination: hardened manifolds that no longer grip, clamps that aren't biting the engagement area, and nothing supporting the carb's weight after the factory airbox came off. Fresh pliable manifolds, clamps set flush with the manifold edge, and a proper support fix it.
Will these work with pod filters?
Yes. Pods remove the factory airbox that helped support the carburetors, so add a hanging support to carry the weight. Our angled boot pod filters for the 450 and CB500T pair with these manifolds, and the install video above walks through the whole setup.
Do these fit my CB350, SL350, or CB360?
No — each family has its own manifold. Grab the CB350 / CL350 / SL350 K0 version, the SL350 K1-K2 version, or the CB360 / CL360 / CJ360 version instead.
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Last updated: July 2026
