Petcock | Honda CB500T / CB550F / CB750

Petcock | Honda CB500T / CB550F / CB750

When the rubber inside an old petcock dries out, it starts to weep at the lever, won't shut off cleanly, or lets the tank drain down into the carbs. This is the direct replacement for the "mid generation" thread-on petcock Honda used on the CB500T, CB550, and CB750 through 1976.

Why You Need This

By the mid-1970s Honda was revising its fuel tanks and petcocks almost year to year, and a lot of it was poorly documented at the time. This is the design we call the "mid generation" petcock, and you can spot it by three things: it threads onto the tank and takes a 24mm wrench, it has a dual-outlet body, and it has no sediment bowl. If that matches what came off your bike, this is your valve.

It fits the CB500T, the CB550 K1 and K2, every CB550F, and the 1975-1976 CB750, including the K5, K6, and CB750F. The CB500T is the odd one out: it has its own fuel tank, unique to that model, and this is the petcock it runs.

Specifications

Which Petcock Does Your Honda Use?

Honda ran three different petcock designs across this era and they don't interchange. Pull yours off and look at how it mounts and how many outlets it has:

• Sediment bowl, bolted on with two screws through the body — that's the early-generation petcock (CB500K, CB550 K0, CB750 K0-K4). Get the early-generation petcock here.
• Threads on, dual outlet, no sediment bowl — that's this one, the mid generation, used through 1976.
• Threads on, single outlet — that's the late 1977-and-up design (CB550 K3-K4, CB750K, CB750F). This petcock won't fit those tanks; get the late-generation petcock here.

Model-Specific Notes

• CB500T: This petcock fits and flows fine, but the layout differs from the original. The factory CB500T petcock has side outlets for carb clearance; this one exits from the bottom, so you may need to position it sideways or rearward to clear the carbs.

Installation

Difficulty: Beginner

Tools needed: 24mm wrench or large adjustable wrench

1. Turn the fuel off, disconnect the fuel lines, and drain the tank before you start.
2. If there's any rust or debris in the tank, clean it out first — a clean tank and a fresh petcock screen are what keep junk out of your carbs. Our tank-cleaning guide walks through it.
3. The petcock body has reverse threads where the connector meets it, while the threads into the tank are normal. Back the connector off the petcock until the threads just start to engage, then start the connector on the tank threads.
4. As you tighten the nut, the tank and petcock draw together evenly and compress the sealing gasket in the middle of the body. Snug it with a 24mm or large adjustable wrench, just tight enough not to leak. Don't over-tighten.

We don't recommend running an inline fuel filter. With a clean tank and the petcock's built-in screen, debris shouldn't reach the carbs, and an added inline filter can choke fuel flow enough to cause running trouble at higher RPM.

Frequently Asked Questions

Will this fit my CB500T?

Yes. The CB500T uses its own unique fuel tank, and this is the petcock for it. One thing to know going in: the factory CB500T petcock has side outlets, while this one exits from the bottom, so you may need to turn it sideways or rearward to clear the carburetors.

Can I rebuild my petcock instead of replacing it?

If your original Honda petcock is just tired, our petcock rebuild kit refreshes the internal rubber on the factory valve. Note that it rebuilds the original Honda cock only — it does not fit this replacement petcock. If yours is too far gone, or you'd rather just swap it out, this petcock replaces the whole valve.

My petcock leaks or won't shut off. Is this the part I need?

That's the classic sign of dried-out internal rubber, so yes, the valve needs attention. Fuel that keeps flowing with the lever OFF, or a weep at the lever, points to worn seals. Rebuild the original with the kit above, or replace it with this one.

You Might Also Need

• Early-Generation Petcock — the sediment-bowl style for CB500K / CB550 K0 / CB750 K0-K4
• Late-Generation Petcock — the single-outlet 1977-and-up design for CB550 K3-K4 / CB750K / CB750F
• Petcock Rebuild Kit — refresh the internal rubber on your original Honda valve (does not fit this replacement)
• Fuel Line | 5.5mm Clear Poly — replace dried, cracked fuel line while you're in there

Last updated: July 2026