Denso W20EX-U spark plugs

[jetmechmarty]

I bought a set of Denso W20EX-U. It looks to me that they will go in a little deeper than the OE NGK plugs.

I’d like to know if anyone on this forum is successfully or has successfully run with these spark plugs. My bikes are 1980. Of particular interest is clearance.

[cajun31]

Marty, Doing a quick google search/comparison of the two it shows the following: (The reach is the same as the NGK.) I have never used the Denso.

Cross-Reference & Equivalency

• Direct Match: The Denso W20EX-U is manufacturer-rated as a direct functional replacement for the NGK BP6ES, as well as the Champion N9YC and Autolite 63. [1, 2]

Key Specifications Comparison

Manufacturer	Denso (Japan / global production)	NGK (Niterra / Japan / global production)
Thread Size / Pitch	14mm x 1.25mm	14mm x 1.25mm
Reach	19mm (3/4")	19mm (3/4")
Seat Type	Gasket	Gasket
Heat Range	Denso 20 (medium-cold; equivalent to NGK 6)	NGK 6 (standard medium heat range)
Electrode Design	U-Groove ground electrode (improved spark kernel generation)	Standard copper-core V-groove / standard center electrode

Design Differences

• Denso U-Groove: The "U" designation in Denso W20EX-U refers to a U-shaped groove cut into the ground electrode. This design forces the spark to the edge of the electrode, allowing a larger flame kernel to grow more quickly for potentially more complete combustion.

• NGK Copper Core: The "P" in NGK BP6ES denotes a projected insulator tip, "B" denotes a 14mm thread size, "E" denotes a 19mm reach, and "S" denotes a standard copper core. NGK plugs are widely trusted as factory-spec or OEM-equivalent choices for classic European and Japanese carbureted engines (such as older BMW, Volvo, Datsun, and Triumph models).

[jetmechmarty]

The Denso looks like it might reach farther into the cylinder. Thanks for the response.

[Bonz]

If they were straight side by side and the picture was from straight on top it might be more visible, however I don't see a difference?

[cajun31]

The Denso looks like it might reach farther into the cylinder. Thanks for the response.

Like Howard said I don't see a difference. The Denso is a direct replacement for the BP6ES. The reach is identical. I wouldn't be a bit worried with using them.

[Schming]

If the plugs measure the same then "Bobs your Uncle"

[jetmechmarty]

I measured. The Denso is almost a millimeter longer. That’s probably inconsequential.

Thanks for the responses. I had incorrectly assumed someone would tell me they’re running them, seeing as BP6ES is tough to find except for the counterfeits on eBay and Amazon.

[DiverRay]

I did run the Denso plugs a few years ago with no problems. There probably is a little more room than you think in the combustion chambers. Remember, these were built to run on regular gas, not premium.

[Bonz]

Not having problems is what's to be expected, they are a direct replacement.

[bikerphil]

The picture may be deceiving, although it appears the porcelain sticks out further on the Denso which would mean a higher heat range than the NGK.

[Bonz]

If the brand was the same, different porcelain could make a difference. Totally different brands, totally different construction in my opinion. Just run them, a millimeter is nothing if that is the difference.