Clearing Up Spark Plug Confusion

[ThisGuy]

Two sparks plugs have been specified by Triumph: DPR7-EA9 and DPR8-EA9

One post from 2012 seems to say they started with the 8, and now specify a 7.

Another post from January seems to say the opposite.

My service manual, purchased in 2007, specifies the 8, so I'm assuming that was the original, and they later changed to 7s.

Can we get an unambiguous, definitive answer on what is currently recommended?

Bonus questions: Does it matter which you use? Does you have a preference? I read at least one post saying his bike ran poorly with new 8s, but was good when he switched back to 7s. Anyone else had this experience?

 

[Triple Trouble]

Two sparks plugs have been specified by Triumph: DPR7-EA9 and DPR8-EA9

One post from 2012 seems to say they started with the 8, and now specify a 7.

Another post from January seems to say the opposite.

My service manual, purchased in 2007, specifies the 8, so I'm assuming that was the original, and they later changed to 7s.

Can we get an unambiguous, definitive answer on what is currently recommended?

Bonus questions: Does it matter which you use? Does you have a preference? I read at least one post saying his bike ran poorly with new 8s, but was good when he switched back to 7s. Anyone else had this experience?

My 2005 came with DPR8 EA9 and when it needed the update kit it they installed DPR7 EA9'S which came with the kit.

 

[TRIIICK]

I just bought NGK DPR8EA9's Gap 0.035 in (0.9mm)

 

[TURBO200R4]

just my opinion
i would not run any plug for 100.000 miles if u do u might not be able to get it out of the head or it brings all the threads out with the plug.
also plugs going down i blow them out with compressed air before removing so a little rock or something goes into the cyl. on some ford motors u have to break them loose then spray them good and let them soak so u don't break the end of the plug off in the head.

 

[ThisGuy]

Doing some more research to learn about the difference between the two heat ranges. Here is NGK's page about it. There is a lot of information here about heat range:

NGK Spark Plug Basics

Also their video link to YouTube doesn't work. Here's the video they meant to link:

 

[sonny]

Pulled DPR7EA-9 out of 2015 Rocket X. Guess what is going back in?

 

[Rocket Geezer]

My 2006 service manual calls for 8-ea9.

 

[ThisGuy]

The video @TRIIICK shared basically boils down to, put the same plugs in that came out. @sonny that seems to be your point as well. I get it, but also that advice is a lot easier to follow if you have a 2015 with the "7" plugs, which seems to be the current spec. You have no reason to question it.

But I think for those of us with older bikes replacing "8" plugs, it's worth questioning. It's the same motor. So at some point Triumph decided, after years of production and thousands of bikes, to change the plugs. Why? By reading the NGK link I shared, one level of heat rating sounds to be reasonably significant. Obviously if I have 8s, replacing them with 8s will still work. But I think it's a reasonable question to ask if the current spec is different, why they made the change, if anyone's seen any noticeable difference, and if I might want to change as well.

I have a habit of going to great lengths and getting into the weeds to research minute details so I can be confident in the final answer. Even if the answer is that it really doesn't matter, I want to understand why and be sure. Just trying to learn.

 

[sonny]

Me too. Plugs came out clean and no issues while riding. I am a firm believer in if it ain't broke why try to fix it. Doing a lot of maintenance and upgrades on the bike. Plugs even after 25,000 miles plus looked real good.

 

[ThisGuy]

I'm satisfied with this answer…

On the official Triumph site, they sell both the 8 and 7 plugs.

On the page for the 8 plugs, under Details/Technical Information, this plug is listed for use by nearly 30 models, NOT including ANY Rockets: NGK DPR8-9EA

On the page for the 7 plugs, they list ONLY the R3 Classic, Roadster, and Touring: NGK DPR7-9EA

So, the 8 has been their go-to plug for many models for a long time, and they only deviate from it for specific reasons. On the 8 page, some of the models listed are only for particular VIN ranges. This shows they are detailed in their descriptions, and if they only meant for 7 plugs to be used in Rockets from a certain point forward, they would specify that. They clearly intend to switch to the 7 plugs in ALL Rockets.

Why? I haven't been able to find any definitive information on this from the Triumph engineers or secondhand sources, but based on the info in that NGK link above, there's a good chance they were seeing enough fouling to make the switch to a hotter plug.

My Conclusion: In this case it's not as simple as replacing the plugs that were already installed, as indicated in replies above. Triumph learned something that justified switching plugs, and while the 8s may continue to work perfectly well for many Rockets, I'm convinced it's worth making the switch to 7s in older models.