Graphite Exhaust Gasket | Honda CB350 / CB360 / CL450
The gasket between your exhaust pipe and muffler is one of the most overlooked parts on a vintage Honda. It sits inside the muffler inlet, hidden from view, and when it fails you get an exhaust leak at the pipe-to-muffler junction. The result is a popping sound at the muffler, reduced back pressure that throws off your carburetor tuning, and carbon buildup on the outside of the joint.
Why You Need This
The factory exhaust gaskets on the CB350, CL350, CB360, CL360, and CL450 are either missing, crumbled, or so compressed they no longer seal. An exhaust leak at the muffler joint lets exhaust gases escape before they reach the muffler — reducing back pressure and making the bike harder to tune. You’ll hear it as a ticking or popping sound near the pipe-to-muffler connection, especially at idle.
This graphite replacement compresses and conforms to the pipe and muffler surfaces when you tighten the joint, creating a tight seal. If you’re replacing your mufflers this is a must-have addition, but even if you’re just trying to get your factory exhaust system running right, a fresh set of gaskets makes a real difference.
Specifications
| Spec | Detail |
|---|
| Replaces OEM Part Numbers | 18392-MK4-000, 18391-317-000, 18391-317-010 |
| Fits Models | CB350 K0–K5 (1968–1973), CL350 K0–K5 (1968–1973), CB360G (1974), CB360T (1975–1976), CL360 K0–K1 (1974–1975), CL450 K0–K6 (1967–1974) |
| Material | Graphite |
| Sold As | Individual (order TWO per bike) |
Note: Sold individually — you need TWO to replace both sides. CL350, CL360, and CL450 owners running the stock scrambler exhaust only need ONE, because one of the exhaust pipes is welded directly to the muffler on the CL models.
Note: The CJ360, CB450, and CB500T use a larger diameter exhaust pipe and require a different graphite gasket — see our CJ360 / CB450 / CB500T Exhaust Gasket.
Installation
Difficulty: Beginner
Tools needed: 12mm wrench or socket, flathead screwdriver, wire brush
- Remove the mounting nuts from the back of the muffler and the 12mm nuts on the exhaust flange at the cylinder head. Slide the pipe and muffler off the bike.
- Separate the muffler from the pipe. The old gasket sits inside the muffler inlet — it may be covered in carbon and hard to see at first.
- Pry out the old gasket with a small flathead screwdriver. Clean the mating surfaces on both the pipe end and the muffler inlet with a wire brush until they’re free of carbon and debris.
- Slide the new graphite gasket onto the end of the exhaust pipe.
- Reassemble the pipe and muffler, then reinstall the assembly on the bike. Snug the mounting nuts — don’t over-tighten. The graphite compresses and conforms to seal the joint.
Clean the mating surfaces thoroughly before installing the new gasket. Carbon buildup on the pipe or muffler inlet prevents the graphite from making a proper seal.
Frequently Asked Questions
Will this fit my CJ360, CB450, or CB500T?
No. The CJ360, CB450, and CB500T have a larger diameter exhaust pipe and use a different graphite gasket (OEM 18392-MK5-000). We sell that one separately — see our CJ360 / CB450 / CB500T Exhaust Gasket.
Do I need one or two?
Most bikes need TWO — one for each side. The exception is the CL scrambler models (CL350, CL360, CL450) with the stock exhaust system, where one pipe is welded directly to the muffler. In that case you only need ONE.
What’s the difference between the graphite gasket and the copper exhaust gasket?
They go in different locations. The graphite gasket seals the joint between the exhaust pipe and the muffler. The copper gasket seals the joint between the cylinder head exhaust port and the exhaust pipe. Most bikes need both — copper at the head, graphite at the muffler. We sell copper exhaust gaskets for the CB350 / CB360 and the CB450 / CB500T.
How do I know if my exhaust gasket is bad?
Look for black carbon deposits around the pipe-to-muffler joint — that’s exhaust gas escaping past the gasket. You may also hear a ticking or popping sound near the muffler, especially at idle. A failed gasket reduces back pressure, which can make carburetor tuning difficult.
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Last updated: March 2026
