Do you gap Iridium plugs?
Thread Starter
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Tourer
Joined: Mar 2008
Posts: 422
Likes: 3
From: PA
Do you gap Iridium plugs?
For those of you that use Iridium plugs, did you gap them before installation? There are a few different makes of Iridium plugs on the market these days (NGK, Autolite, Denso etc). It seems a lot of people on the forum like the NGK plugs so I was thinking about buying a set. There seems to be varying opinions regarding plug gap. Ive read that some people install them out of the box because they are already gapped correctly from the manufacturer while others still set the gap to Harleys recommendation (38 t0 42mm). Ive heard that the default gap for the NGK Iridium plugs that fit Harleys is about 20mm. If you use Iridium plugs did you gap them or install them straight from the box?
Road Master
Joined: Sep 2007
Posts: 818
Likes: 1
From: S/W Ohio
Always check the gap. Unless they're packed really well with the end protected I would at least check the gap. I've seen some that were probably dropped or hit on the end and had the gap too small, it only takes a second to verify.
Thread Starter
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Tourer
Joined: Mar 2008
Posts: 422
Likes: 3
From: PA
Thanks for the replies. I certainly understand the need to check the gap but I was curious if people gap Iridium plugs. The pre-set gap on Iridiums is about 20mm less than what Harley recommends a standard copper plug be set at.
Do most people that install Iridium plugs leave the plug at the pre-set gap (around 20mm) and install it or do they gap the plug at 40mm before installation? That's what I'm trying to find out.
Thanks.
Do most people that install Iridium plugs leave the plug at the pre-set gap (around 20mm) and install it or do they gap the plug at 40mm before installation? That's what I'm trying to find out.
Thanks.
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Road Warrior
Joined: Nov 2009
Posts: 1,635
Likes: 13
From: 501
Iridium plugs are overkill in most cases. I am a NGK fan and user, but when my plugs need changing I will go for the standard NGK U-groove plugs. A local speed shop owner here has one of the counter top splitfire plug sparking devices which lets you see the type of spark you will get out of any plug. Steve claims that the NGK U-grooves proved to be as good or better performing plug than the mighty expensive "Splitfires" and many others. The U-grooves can be had for a fraction of the price of many newer plugs on the market. I wish I could give you the part number, but I have only recently begun to consider changing mine.
I will post back when I find the correct part number for the 88 TC motor.
$0.02
aka Bob
Addendum; If an Iridium plug is designed to go into the Harley, I would consider the gap they use. Just check them both for consistency.
I will post back when I find the correct part number for the 88 TC motor.
$0.02
aka Bob
Addendum; If an Iridium plug is designed to go into the Harley, I would consider the gap they use. Just check them both for consistency.
Last edited by Turbo Turtle; Jun 21, 2010 at 12:36 PM. Reason: Additional info
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Cruiser
Joined: Mar 2008
Posts: 210
Likes: 1
From: West Chester, PA
For those of you that use Iridium plugs, did you gap them before installation? There are a few different makes of Iridium plugs on the market these days (NGK, Autolite, Denso etc). It seems a lot of people on the forum like the NGK plugs so I was thinking about buying a set. There seems to be varying opinions regarding plug gap. Ive read that some people install them out of the box because they are already gapped correctly from the manufacturer while others still set the gap to Harleys recommendation (38 t0 42mm). Ive heard that the default gap for the NGK Iridium plugs that fit Harleys is about 20mm. If you use Iridium plugs did you gap them or install them straight from the box?
Road Captain
Joined: Jan 2009
Posts: 739
Likes: 2
From: St. Louis
I agree, always double check the gap. Also, I was told that if they need to be gapped, use a tool that won't mar the Iridium finish. It's a very thin layer and can easily be scratched away. You paid good money for them, there's no sense in ruining them before they even make it in the bike.