What's your take on Iridium spark plugs?

[oldbike54]

A person that knows just enough can sometimes be dangerously naive. 

 Heck , I don't claim to understand any of this , just asking questions  OK where is Triple Jim or Kiwi Roy ?

 Dusty

[canuguzzi]

In the real world, spark plugs like anything else are all part of the whole system, there is no magic plug that makes everything else better anymore than some certain oil makes the engine run better if it is worn.

If something works or you, ok. Theories are great, the patent office is filled with entire collections of them. How that makes a difference if the bike performs like you want it to when you grab a handful of throttle really doesn't matter.

[kevdog3019]

In the real world, spark plugs like anything else are all part of the whole system, there is no magic plug that makes everything else better anymore than some certain oil makes the engine run better if it is worn.

If something works or you, ok. Theories are great, the patent office is filled with entire collections of them. How that makes a difference if the bike performs like you want it to when you grab a handful of throttle really doesn't matter.

Yes... A small piece of the puzzle. Make enough small differences...
Like tranny oils I've used... one that works in one bike and shifts very pleasantly did not do so in the other. Through happenstance I found a different oil did much better in my SB trans for more positive shifts. Same went for these plugs. I can't explain it but I will try them in my Super Lario to see how they react there.  No favorable results in my stock Lario.

[CalVin2007]

So in other words ... I really think some of the thinking here is backwards , in the real world shouldn't a copper conductor outperform a less conductive metal . Yeah , the gap thing and all , but what am I missing here ? Seems basic physics still applies .

 Dusty

    Dusty,the copper in a standard plug isn't used for the electrodes where the spark jumps the gap. The copper is in the inner central core leading to the center electrode,which is a steel alloy. The longer life plugs fuse an iridium or other longer -wearing material to the electrode gap surfaces or replace the lower center part with a fine wire.

[oldbike54]

    Dusty,the copper in a standard plug isn't used for the electrodes where the spark jumps the gap. The copper is in the inner central core leading to the center electrode,which is a steel alloy. The longer life plugs fuse an iridium or other longer -wearing material to the electrode gap surfaces or replace the lower center part with a fine wire.

 Thanks Terry . However , isn't that more to prevent wear over time than for initial performance ? Help me out here , really trying to get a good grasp of this .

 Dusty

[Kev m]

So in other words ... I really think some of the thinking here is backwards , in the real world shouldn't a copper conductor outperform a less conductive metal . Yeah , the gap thing and all , but what am I missing here ? Seems basic physics still applies .

 Dusty

Depends on what you mean by outperform.

The copper core will wear much faster and the gap should in theory grow to a point beyond the ignition system's ability and/or I believe stress the coils (attempting to pull too much voltage).

The potential advantage of the copper core plugs would be lower initial cost making them easier to throw away when the gap widens and/or if they are fouled by mechanical or tuning issues.

[pikipiki]

Not required on Guzzi's as the benefit is in not having to change them as they last 3 times as long.
Changing Guzzi spark plugs is so easy that it's almost inconcievable to ride a Guzzi over 50,000 miles without ever inspecting the plugs.

[canuguzzi]

In all this there is one other factor which shouldn't be discounted, personal preference by each person to just use what they think is the best. That can go against tests, charts and all the rest. In the same way some people will never use  Fram oil filter, much of what happens is what you believe happens.

Take a bike with horribly dirty oil but was of a certain brand (one if the best?). It runs ratty but it gets changed with a non name oil and feels to run better. Someone somewhere will swear that it was the oil, not the oil change that made all the difference and that the brand had little if anything to do with it.

No doubt some stuff performs better than other stuff but how much of the experience is perceived vs reality?

[CalVin2007]

Thanks Terry . However , isn't that more to prevent wear over time than for initial performance ? Help me out here , really trying to get a good grasp of this .

 Dusty

  That's correct. Increased performance over standard plugs in some applications is a possible side effect of the spark kernel placement relative to the combustible charge in the cylinder. If your particular application does not specify such plugs then you pay your money and you take your chances.

  Terry

[kirkemon]

I loved the NGK BUHX on my H1 - they were flat, never had to gap them!

[oldbike54]

  That's correct. Increased performance over standard plugs in some applications is a possible side effect of the spark kernel placement relative to the combustible charge in the cylinder. If your particular application does not specify such plugs then you pay your money and you take your chances.

  Terry

 Well sure  Actually that makes perfect sense . What about in Diesels ?

  Someone needs to use the screen name "Colonel Sparky" 

  Dusty

[rodekyll]

A good rule of thumb on all this is that if your performance changed by changing spark plugs, the spark plugs needed changing.  If it doesn't then the problem is somewhere else. 

I'm reading all sorts of empirical data suggesting that changing to iridium plugs immediately made the bike run better.  I believe it.  Probably cleaning and regapping the ones that were in there would have also improved the engine running.  What I don't read is where anyone PROVED the difference was IRIDIUM by popping in a NEW set of their old spec plug and doing a quantitative comparison.  I'm guessing that with any new plugs under the same circumstances with the same gas most folks couldn't tell the difference between iridium and anything else.

What seems to be beyond dispute is the increased service interval using iridium.  They do seem to hold a gap longer.

[Farmer Dan]

WOW!  This is more fun than an oil thread.  For the last few days I've been running on a brand new pair of NGK 7333 plugs.  I ordered the NGK iridium plugs from NAPA but they were a no show.  I'll pick them up Monday (if they show up by then).  That will give a week of riding and gas mileage to give a true comparison.

[Farmer Dan]

should mention the part number for the iridium is NGK 6637.  Good luck finding them in stock though LOL

[pete mcgee]

I have a 1984 LeMans 3 with nearly 200,000 miles on it.
I used to change the spark plugs every 6,000 miles, they needed it.
I have had 1 spark plug blow out of the head due to the thread failing, one helicoil come out with the plug etc.
Around 20,000 miles ago I fitted iridium plugs, I twin plugged the heads around 20 years ago, so I fitted 4.
I have removed and inspected them once, no fouling, no discernable wear, no real improvement to anything except plug life and less wear and tear on the threads for the spark plugs in the heads.
They work as advertised and suit my maintenance requirements.
Cheers

[n3303j]

Had a '66  BMW R60/2 that I recently sold.
Kick start and a magneto ignition.
You get the weakest spark at starting because all is turning slowly.

The fine wire tip of the Iridium plug lends itself to more easily generating an arc (point discharge).
My /2 started a bit more easily (1 kick instead of 2 or 3) with the Iridium plugs.
The idle was a bit smoother at really slow rpm.

At speed the magneto generated plenty of current.
The difference was less noticeable there.

[crock]

The idle on my Breva 1100 was noticeably smoother after changing to Iridium outer plugs.

[rodekyll]

It idles smoother after you changed the outer plugs to iridium from old used-up plugs or from fresh, new ones?

This is part I'm having trouble sorting out.  Folks are saying they changed plugs to iridium and the bike ran better.  This suggests the bike was running less the better before the change.  But unless you were changing to new iriduims on a tuned bike from new [insert brand and type here] plugs on a tuned bike you're not looking at the differences between two types of spark plugs.  You're looking at the results of replacing clapped out consumables with fresh.  In some cases you've changed the air and fuel filters, adjusted the valves, tweaked the fueling, AND changed the plugs -- but attribute the improvement to iridium.  See my problem?

I'm not concluding anything about iridium's place in the pecking order.  I'm not saying the reports are bunk.  I'm just saying that the punch line doesn't follow the setup.

[BRIO]

I noticed a difference in the idle when I replaced my standard plugs with new standard plugs. Also the 1151 comes with inner Iridium plugs from the factory as far as I can tell and the good kind too. NGK platinum laser.

[kevdog3019]

If the old plugs were within the 6k mile range per the owners manual for replacement then they are NOT clapped out. Mine was well within before the change. If you want to argue how much within, then nobody should be using regular plugs if they deteriorate that much within that timeframe. Just a better case for iridiums in my book. I'm also not claiming using them, but I'm also saying "clapped out" should be beyond the service manual designation, no??

I realize you want to compare apples to apples but you bring up another VERY valid point about deterioration. This is important to note as well as it could be a bigger point to all this discussion. It is well-documented that the iridiums don't deteriorate at nearly the rate a regular plug will. Explain "clapped out" RK?

[rodekyll]

"clapped out" is a description of condition.  It means "out-of-serviceable range for whatever reason."  "owner's manual" is words on a page.  Given the choice, I'll go by condition the object, not by what's written about the object. 

But working backwards toward a baseline that your butt remembers from the last tune up is not the way to do a comparison.  You establish the baseline and then compare.  So it doesn't matter a whit what the book says about the old plug's service interval.  If the plug is used it's used and not a fair comparison to a new plug. 

If you want to see what difference a spark plug makes, you tune the machine, including fresh plugs of the old type, and then compare that performance to the same conditions with the new type plug.  Anything else is not a valid test.

Again, I'm not saying iridium is better or not.  I'm just saying that these antidotal reports are just that -- stories about sparky things.  If folks would go that extra step and swap in and out new plugs of both types against the tuned baseline and report back, then we'd have something here.

[kevdog3019]

I agree that's a fair test; in the same breath I would say it would be fair to test each after several thousand miles in the same bike. If what you say is things deteriorate to that point, then this is also a valid test. Iridium's are built for longevity and regulars are not. This is only fair to an iridium. I can take a new tool at HF and loosen the same bolt as using a Snap-on when new...
Years later?

[steven c]

 I put an iridium plugs in my 2 stroke and thumper and right away felt my wallet was lighter! They do seem to last longer and foul less.

[rodekyll]

I put an iridium plugs in my 2 stroke and thumper and right away felt my wallet was lighter! They do seem to last longer and foul less.

Now there are some conclusions I can accept without further study.   

[krglorioso]

Using the NGK Iridium plugs in my 03 Stone Touring with satisfaction.  I sourced them on E-bay a couple of years ago for $15/pair postpaid.  Have several thousand miles on them; no complaints at all.

[tris]

Funnily enough I ordered a set of Iridium NGK 6637s 10 minutes ago for my B11

Bike is a bit "missy" so I assume it needs new plugs and bought the Iridium's just to see.

If that doesn't sort 'er out I'll change the inners too - but they've only done 2-3 thousand miles so should be OK for a while yet

[Farmer Dan]

Parts guy at NAPA tells me the NGK 6637 plug is not available anymore.  I need to find a better parts store.

[Dofin]

Up date on the DENSO 5362 iridiums I put in my 2015 V7 stone.  Left side One failed oddly and showed rich dark and the right side was good.

The failed one showed some fracturing in the ceramic and seemed to allow a slight compression leak.  SsOoo I cant give a performance input!

I missed it, what is the NGK CPR8EB-9 iridium replacement ??  I  couldnt find one.

[old as dirt 2]

Parts guy at NAPA tells me the NGK 6637 plug is not available anymore.  I need to find a better parts store.

and he is an idiot, google shows ALOT of places you can get them from

[LowRyter]

Put them in my V11 Lemans and noticed a good difference.  Tried them in my older Lario and no difference.  I feel they foul easier so if I were using carbs I wouldn't go there, FI try them you may feel a better pull and quicker response.  My buddy noticed it in both his V11's also.  Supposedly a bigger kernel.  Worth the experiment I feel from my (our) experience.

hmmmm.  might be worth a try on my V11s.  With Guzzi electronics / ignition, I would think any help might be an improvement.