Spark plug choices
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6th Gear
Joined: Sep 2022
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From: Northern California
Spark plug choices
Hello, I have the 2003 Road king CVO. In the manual, it states that only the recommended spark plug should be used. When this book was written I don't think they had the variety of plugs that we have today. Has anyone used the E3 plugs in their older twin cam bikes? And with what results?
I would like to try them, but also like to follow MFG recommendations.
I would like to try them, but also like to follow MFG recommendations.
Stellar HDF Member
Joined: Jan 2017
Posts: 2,673
Likes: 2,076
From: Massachusetts
Hello, I have the 2003 Road king CVO. In the manual, it states that only the recommended spark plug should be used. When this book was written I don't think they had the variety of plugs that we have today. Has anyone used the E3 plugs in their older twin cam bikes? And with what results?
I would like to try them, but also like to follow MFG recommendations.
I would like to try them, but also like to follow MFG recommendations.
Stellar HDF Member
Joined: Jan 2017
Posts: 2,673
Likes: 2,076
From: Massachusetts
The only thing superior, is you wallet gets lighter.
Seasoned HDF Member
Joined: May 2018
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From: Las Vegas
The only thing E3 is good at is marketing. They do an excellent job of turning normally intelligent people into suckers. Don't be one.
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Stellar HDF Member
Joined: May 2007
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From: USA
I recall Utube - The Farm Project - has tested E3 and all types of spark plugs.
Good luck with your decision.
FWIW
Copper plugs flow electricity the best, yet have the shortest life.
Since Harley plugs are typically easy to remove, I always go with copper.
Multiple electrodes, well, see Farm Project or other.
Heat range, air fuel ratio (ie plug reading) could be considered more important than plug design.
Good luck with your decision.
FWIW
Copper plugs flow electricity the best, yet have the shortest life.
Since Harley plugs are typically easy to remove, I always go with copper.
Multiple electrodes, well, see Farm Project or other.
Heat range, air fuel ratio (ie plug reading) could be considered more important than plug design.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,143
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From: San Diego, CA
The Harley 6R12 plugs (#32362-04, formerly #32317-86A) will do everything you need on a street driven motorcycle....
If you don't have a dealer near by, use Champion Copper Plus RA8HC plugs.
That Champion plug is not an equivalent plug, it is the exact same plug as the 6R12. Champion makes (unless there was a recent change) the 6R12 plugs for Harley, and the RA8HC is their version of the same plug.
IMHO... With the ease of plug changes on the Twin Cams, and the low cost of the 6R12 or Champion RA8HC plugs, there really is no reason to look elsewhere...
You can get plugs of exotic metals that will last longer, and plugs with revolutionary designs that will cost more, but you won't find a plug that runs any better than the 6R12 or Champion RA8HC.
And yes, they both work well with the Harley ION Sensing knock detection system.
FWIW.... The 124" S&S crate engine for my '16 Bagger (135HP & 151TQ) came with Champion RA8HC plugs...
