What size is a Honda spark plug spanner?
The most common spark plug hex size for Honda engines is 14 mm, so you’ll typically use a 14 mm spark plug wrench or socket. Some models or very small equipment may use different sizes, so it’s best to verify with the manual or by inspecting the plug itself.
What size is typically used across Honda engines
The size refers to the hex across flats on the spark plug. The accompanying socket is sized to fit that hex, while the drive size (3/8" or 1/2") depends on your ratchet or impact wrench. The following sizes cover what you’re likely to encounter on Honda equipment.
- 14 mm hex (most Honda car engines and many motorcycles): Use a 14 mm spark plug socket on a 3/8" or 1/2" drive ratchet.
- 12 mm hex (some very small engines or older equipment): Use a 12 mm spark plug socket; more common on certain compact Honda power equipment.
- 16 mm hex (less common, limited to specific engines or aftermarket plugs): Use a 16 mm spark plug socket; check model specifications.
In practice, 14 mm covers the vast majority of Honda plugs. If you’re unsure, consult the owner's manual or measure the plug hex to confirm before buying tools.
How to identify the right size for your model
Follow a simple verification process to ensure you have the correct tool for your Honda.
- Check the service or owner's manual for the exact spark plug specification for your model.
- Inspect the spark plug you remove and measure the hex across flats with a caliper or a spark plug gauge.
- If the hex looks like 14 mm, start with a 14 mm spark plug socket (3/8" or 1/2" drive depending on your toolkit).
- If the hex is noticeably different, switch to a 12 mm or 16 mm socket as needed and recheck the fit.
- When in doubt, contact a Honda dealership or a qualified technician with your model information.
Using the correct size helps ensure proper fit, prevents stripping threads, and allows accurate torque when installing the new plug.
Summary
For most Honda engines, the standard spark plug spanner is 14 mm, matching the common plug hex across many cars and motorcycles. While 14 mm is the default, some very small or older Honda equipment may use 12 mm or 16 mm. Always verify with the model’s manual or by measuring the plug, and use the appropriate socket and drive size. Adhering to the correct size helps avoid cross-threading and ensures proper torque during installation.
