How do you regap a Iridium Spark plug?
Seasoned HDF Member
Joined: Mar 2009
Posts: 24,746
Likes: 9,264
From: Snow Hill, NC
I use HD SE triple platinum, twice now in 60000 miles, i checked the gap twice and it was spot on...When i took them out at 45000 miles they really didn't need changing but i had gift card and bought a bunch of oil and filter and plugs and wires and etc....I still keep the old ones in the tool pouch in case.
Road Captain
Joined: Apr 2018
Posts: 627
Likes: 324
From: Covington, VA
No, iridium's are NOT gapped at the factory for your specific needs. Yes, they are pre-gapped to one size but don't ***-U-ME anything. I gap mine with a very fine needle-nose pliers with a 45-degree angle tip to OPEN the gap and a gentle tap on a wood block to CLOSE the gap. I measure with the standard feeler gauge and NOT a disc type. NEVER touch the tiny wire tip.
https://cv-performance.com/ngk-6046-...ium-spark-plug
On my 2005 Sportster, I've compared the NGK copper against the NGK iridium and although there is no apparent power difference, the iridium plugs respond to the throttle sooner when warming up without acting so "lean". Once fully warmed up, the engine feels the same with both. I'm sticking with my iridium's. They last so long, they will be just as cheap - if not cheaper - as the copper plugs.
https://cv-performance.com/ngk-6046-...ium-spark-plug
On my 2005 Sportster, I've compared the NGK copper against the NGK iridium and although there is no apparent power difference, the iridium plugs respond to the throttle sooner when warming up without acting so "lean". Once fully warmed up, the engine feels the same with both. I'm sticking with my iridium's. They last so long, they will be just as cheap - if not cheaper - as the copper plugs.
Cruiser
Joined: Oct 2016
Posts: 230
Likes: 156
From: Florence Oregon
Yes SIR, but it is the wrong one. The correct answer is you don't. They are not made that way. But hey it's your money.
Road Captain
Joined: Apr 2018
Posts: 627
Likes: 324
From: Covington, VA
So, you're saying that NGK is wrong, the Blue Book (factory service manual) is wrong, but you are right. OK......
Cruiser
Joined: Oct 2016
Posts: 230
Likes: 156
From: Florence Oregon
Not really. I am saying the 35-year mechanic that I trust is right. Also if you have all that info why the post to ask the question, aren't your sources trustworthy?
Road Captain
Joined: Jun 2013
Posts: 734
Likes: 319
From: Rochester NY
Road Captain
Joined: Apr 2018
Posts: 627
Likes: 324
From: Covington, VA
I didn't post a question. I posted an answer from the manufacturer. I know all kinds of mechanics with many years of experience and just like other people, they tend to disagree with each other from time to time. I would trust the manufacturer more than I would trust one person. By the way, my NGK iridium's are gapped at .040" and run fantastically. But, what do I know? I'm not a mechanic.
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Cruiser
Joined: Oct 2016
Posts: 230
Likes: 156
From: Florence Oregon
I didn't post a question. I posted an answer from the manufacturer. I know all kinds of mechanics with many years of experience and just like other people, they tend to disagree with each other from time to time. I would trust the manufacturer more than I would trust one person. By the way, my NGK iridium's are gapped at .040" and run fantastically. But, what do I know? I'm not a mechanic.
Outstanding HDF Member
Joined: Dec 2012
Posts: 2,557
Likes: 235
From: Texas
I cannot find any reference that HD offers iridium plugs but I do remember reading references to these not being the best choice for high compression engine builds when I was researching my 95 build. I use SE high compression platinum plugs in my Harley and I get them from the local dealers for $19.95/pair. I have higher confidence that these are the correct one for maximizing the performance of my high compression engine. I always check and adjust the gap before I put spark plugs in...even if I just took them out to turn over the engine and I adjust them with a wire feeler guage with the gap adjust feature.