If you check the manual for the TMX 125 Alpha (2021), Honda actually recommends different spark plugs depending on how you ride. If you’re mostly doing city driving, the standard ones are fine. But if you’re like me and you do a lot of long-distance road trips or extended high-speed riding, you’ll want a plug that can handle the extra heat.
Standard Spark Plugs:
- NGK: DPR8EA-9
- DENSO: X24EPR-U9
For Long-Distance / High-Speed Riding:
- NGK: DPR9EA-9
- DENSO: X27EPR-U9
A Quick Look at the Brands
Both of these options use Japanese technology, which is pretty much the gold standard for motorcycle parts.
NGK Spark Plugs
NGK has been around since the 1930s and they are probably the most famous name in the game. Most bikes come with NGK straight from the factory (OEM), so you know they’re reliable. Whether you’re buying an original replacement or an aftermarket upgrade, there’s a high chance NGK has exactly what your TMX needs.
Denso Spark Plugs
Denso is another Japanese giant, born in the late 40s. Fun fact: they actually started as a division of Toyota. Their name is even a combination of the Japanese words for "electricity" and "device." Just like NGK, Denso is a rock-solid choice if you want your engine running smoothly.
- Steffes, T. (2020, October 1). Our story [Blog post]. Retrieved from https://ngksparkplugs.com/en/about-us/our-story
- Chung, D. (2021, May 20). Best motorcycle spark plugs [Blog post]. Retrieved from https://www.motorcycle.com/products/best-motorcycle-spark-plugs
- DENSO. (n.d.). Japan | Global Network | Corporate Information | Who we are | DENSO Global Website [Blog post]. Retrieved from https://www.denso.com/global/en/about-us/corporate-info/global-network/japan/
- Denso. (2022, 29). DENSO at a glance [Blog post]. Retrieved from https://www.denso.com/global/en/about-us/at-a-glance/
