Intermittent misfires and dead cylinders are often blamed on the ignition coils — but the real culprit is usually the spark plug boots. Cracked, corroded, or loose boots break the connection between the coil wire and the spark plug. These replacement boots fit the CB350 and CB360 family of bikes, look close to the originals, and feature a water resistant seal. Sold as a pair.
The spark plug boot is the last link in the ignition chain — it connects the high-tension coil wire to the spark plug. When boots crack, corrode internally, or lose their grip on the wire, spark energy leaks instead of reaching the plug. You'll get intermittent misfires or a dead cylinder. New boots restore a solid electrical connection and seal out moisture.
Note: These boots fit the CB350 and CB360 family only. If you have a CB450, CL450, or CB500T, use our Angled Spark Plug Boot instead — the straight boot will physically fit but is a snug angle on the 450/500T cylinder head.
Difficulty: Beginner
Our ignition system troubleshooting video covers how to test the spark plug boots, coils, points, and condenser on Honda CB and CL twins.
If you're getting intermittent misfires or a dead cylinder, test the boot by removing it from the spark plug, inserting a small screwdriver into the boot where it contacts the plug, holding it close to the cylinder head, and kicking the engine over. If you get spark at the screwdriver but not through the boot on the plug, the boot is the problem.
They will physically screw onto the wire, but the straight angle is a tight fit against the CB450/CB500T cylinder head fins. We recommend our Angled Spark Plug Boot for CB450/CL450/CB500T instead.
Spark plugs come with two terminal types: a terminal nut (threaded onto a stud) and a terminal stud (bare post). These boots fit the terminal nut style. If your plug has a bare stud, check whether the terminal nut was removed — most spark plugs ship with the nut threaded on. Use pliers to check if it unscrews.
Last updated: March 2026
