Can't get your spark plugs out? A proper spark plug socket makes the difference between a clean pull and a cracked insulator. This 13/16" (21mm) 6-point socket is the correct size for the NGK BR8ES and D7EA spark plugs used across the Honda CB350, CB360, and CB450 family — and it works on every vintage Honda we support.
Spark plug removal and installation is one of the most frequent maintenance tasks on a vintage Honda. If you're using a regular deep socket or an ill-fitting plug wrench, you risk cracking the ceramic insulator or rounding the hex. A dedicated spark plug socket has an internal rubber sleeve that grips and protects the plug's ceramic — and holds the plug in the socket so you can install it without dropping it into the cylinder well.
The 13/16" (21mm) hex is the standard drive size for most spark plugs. This KT Pro socket also has an external hex on the end, so in tight-clearance situations where a ratchet won't fit, you can grab it with a wrench.
Note: Some models (CT90, CB175, CB200, CB500K, CB550, CB750) may benefit from our 18mm Thin Wall Spark Plug Socket in tight-clearance situations where the cylinder head recess is narrow.
KT Pro (King Tony) is one of the largest global hand tool manufacturers, producing professional-quality tools in Taiwan. All KT Pro tools carry a lifetime warranty. See our KT Pro Tools warranty process.
13/16" (21mm) — this socket. It fits the NGK BR8ES spark plug used on all CB350, CL350, CB360, CL360, CB450, CL450, and CB500T models.
The 21mm hex fits the plug, but the CB550 and CB750 have narrow cylinder head recesses. If a standard-wall socket won't fit, use our 18mm thin wall socket instead.
A spark plug socket has a rubber insert inside that grips the ceramic insulator and protects it from cracking. A regular socket can crack the insulator on removal and won't hold the plug for installation.
Yes. All KT Pro tools carry a lifetime warranty against manufacturing defects. See our KB article for the warranty process.
Last updated: March 2026
