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We do about 6 to 7,000 miles each year on our GL1500 and each winter I service it and part of the service is new spark plugs (yeah, I know but it's my choice and my money !). Is it worth changing to Iridium plugs for any other reason other than they last longer ? That is, do they make the engine run better, give better mileage, etc, etc ?
 

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Yes Ron they do last longer( they may be the last set you buy , they do not cost much and your bike will noticably run better.
 

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It is said by the wize ones that the spark is more volotile & therefore, the fuel is set off with a better, faster burn. This causes better performance & less fuel per mile.

I have not tried them yet but I will give them a try this spring in my bike.
 

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I heard so many mixxed opinions on them that I decided not to spend the extra on them. Just like spending the extra on split fires for my minivan. i wont do it.

Quadruple platinum, Gimme a break , i thin I need an excuse to loosen the plugs every year and check.
 

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Now adays spark plugs seem to last forever. I've tried several "super plugs" on various vehicles I had thru the years, and couldn't tell any difference from what was installed at the factory.I've also had a work truck that went 105k miles on the factory plugs with no decrease in power or milage. so to me unless your a racer and need to get that last 1/4 horse power out of a motor, that you won't really notice I would say use the cheapest plugs you can find and spend the savings on more go juice.,,
 

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I kicked that idea around for awhile and just decided to stay with OEM plugs. For one thing they will last way past what the manuals say they will. So as long as you are somewhat close to the service interval it is cool.

The main thing I thought about and not such a big deal with a newer bike , but with an older one simply looking at the plugs can tell you a lot about the engine. So I think an occasional set of new plugs is a good thing, simply to know if everything looks ok.

I am however at the moment playing with a set of them, one plug number lower to see if it effects gas mileage.

Kit
 

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Hey all you guys got more dough than I do and I can afford Iridium plugs!!!
They aren't that much more and they really do help.
Splitfire plugs is just another gimmick.
Ask Randakk about the Iridium plugs or the splitfires.
No plugs are going to change your bike into a firebreathing drag monster, they will just give you the very best spark you can get without failing,, mine has a lot of miles on her and burns a little oil so a little help helps.
 

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I use them and they work fine. Their tip design gives a more concentrated spark and the old style ( points ) ignition system can use all the help it can get.

That being said I've found that replacing the plug wires had the most benefit to the ignition system.
 

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Hey guys, over on the Maximum Suzuki board, we have an NGK test engineer who also rides a bandit. This same question came up over there recently. I am cutting and pasting his response since that board is sometimes closed to guests depending on the spam level. Here is one reply.

Hi all,

The OEMs don't exactly think that a plug is just a plug and a spark is just a spark! Obviously we put a lot of time and money in testing and evaluating spark plugs. Iridium (and platinum) plugs help the manufacturers meet their durability, ignitability, idle stability, emissions goals, etc. But I guess it doesn't really matter to most people as long as their bike / car runs down the road.

Just a couple quick, general things about iridium plugs:

The fine electrodes are the key. Because iridium is so hard and doesn't erode it allows for very fine electrodes (small diameter). The fine electrodes allow for:

Lower required voltages - in other words it takes less voltage to jump across the gap. This is easier on the coils, wires, and plugs - less chance for flash-over (out from under the boots) or voltage "puncture" due to dielectric breakdown.

Greater ignitability, better combustion (lower COV% = smoother & greater torque output) and lower emissions. The electrode mass is smaller so more spark kernel heat is transferred to the air-fuel mixture instead of the electrodes. The fine electrodes also allow more of the spark kernel to be exposed to the air-fuel mixture.

Larger gap sizes. Larger gaps can be utilized because the voltage required to jump the gap is reduced. This allows leaner operation without misfire and also contributes to increased ignitability. Because the iridium and platinum plugs don't wear as fast, the large gaps won't get too big.

However, it is true that they don't make much difference for maximum horsepower.

There are other benefits to iridium plugs, but my point is that a spark is not just a spark and a plug is just not a plug. What else would you expect from somebody that works for a plug company?
 

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and one more...

Hi,
Not to blow my own horn, but I am a Test Engineer for NGK Spark Plugs. I also have NGK Iridiums in my 98 1200 (employee discount silly). All you need to do is get your insulators above 400°C and the carbon will burn off. How do you get to 400°C you say? If your jetting is closer now with the new emulsion tubes, one good 10min blast at 70mph should be plenty. The carbon does not reduce the life of the plug - just burn it off. No need to change those plugs if your jetting is close enough and you can still start your engine. Those are the best plugs you can buy - it would be a shame to throw them away.

Iridium plugs don't necessarily get up to operating temperature faster than a nickel plug. The temperature of the electrodes are not related to fouling. It is the ceramic insulator around the center electrode that is related to fouling. A heat range 9 Iridium plug and a heat range 9 nickel plug will have the same insulator temperature characteristics if the insulator design is the same.

The main advantages to the Iridium electrode are: long life (I don't think you can ever wear them out - how far can you ride?), and they require less voltage to fire across the gap. If your jetting is on the rich side those plugs will resist fouling a little longer than a conventional nickel plug because it will be easier to jump the Iridium-tipped gap compared to leaking down the side of the insulator and over to the shell. And no, unfortunately, you won't get more horsepower by using platinum or iridium plugs, but you might notice a little smoother idle due to the better ignitability.

When a plug is fouled, there is still a spark, but it runs down the side of the insulator (on top of the carbon) to the shell. If you can get out on the road and you are hitting on all cylinders, then rev her up and burn that carbon off! Then the spark will have no choice but to jump the gap.

Hope this helps. If your bike wont start, you might have to lightly clean the insulators with a one of those handheld sandblasters in order to get some of the carbon off. By the way, don't try burning the carbon off with a propane torch, etc. The insulator might crack due to the sudden, uneven heating.
 

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Hey, AndyB, what a great reply with expert knowledge... as you could say, "straight from the horses mouth" (not implying that you are a horse, just a common phrase !)

Off to buy some Iridium plugs now.

Thanks for the posting and advice
 

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Ok now the big question is what do iridium plugs cost? and do they make them for all year wings? I know I can get champions for $1.88 each and if I change them at 10k intervals, for 100k miles of riding the cost would be $75.20. What will 100k worth of iridium use cost? Inquiring minds need to know.,,,,,,
 

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Your most likely looking at about 20.00 (or less) for 4 and they may last 100,000! Go to Advance Auto parts or any major auto parts store they will look them up on the computor and they can be there in 24 hours!
 

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They are from $7.50 to $8 dollars per plug.

Kit
 

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Actually I paid 5.99 each over a year ago.
 

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RON WYLIE wrote:
Hey, AndyB, what a great reply with expert knowledge... as you could say, "straight from the horses mouth" (not implying that you are a horse, just a common phrase !)

Off to buy some Iridium plugs now.

Thanks for the posting and advice
Well, thanks for the compliment, but just to be clear, I am not an expert unless you count the ability to cut and paste. That was posted by an engineer on the Maximum-Suzuki boards. But, I thought it would be useful.
 

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The main benefit of a fine wire spark plug, no matter what it's made or, iridium or platinum is better starting especially in cold weather. They do last long since the metal is better able to stand up to the erosion from the arc temperatures. Since the shape of an electrode is critical to development of an arc, a sharper point concentrates the E field of theEMF applied by the ignition pulse which causes the arc to occur at a lower applied voltage. Standard massive electrode spark plugs work well as long as the edges of the electrodes have sharp edges and the center electrode hasn't eroded. As the plug ages the edges tend to round losing their sharp shape which increases the resistance to arcing. Fine wire plugs being just that, fine wire don't develop such larger radius'rounding which increases the arc voltage.



In short, I found them to make the earlier bikes start much easier especially when the battery or starter wasn't the best. I haven't seen much difference on my 1500 but that has a good alternator and Odyssey battery. Worth the money? I do think so on the four cylinder bikes for sure, the later models have a bit better ignition system so the difference might not be as great.
 

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I read in a Wing World Workbench article that they don't really do much for you powerwise, but are practically bullet proof in reliability. I would, however like to try a set on my 1500. jimsjinx
 

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I could be wrong and probably are but it has always been my understanding that, no type or heat range will give you more HP but will last longer and bur the fuel more completely. I have used many different types of plugs in the past in my bikes and have found very little difference except in longevity and fuel economy. I like the iridium because they give quick starts, a lit better fuel eco & last a long time. I had a 94 Grand Caravan 3ltr that had 150k+ km on the clock and plugs (NKG Iridium) still looked new. Just before I traded her off ( my one big mistake in life), I went over the engine to make sure there was no surprises (@ 315000k) when I decided trade her off. I have sworn by them since they came out as I do with Syn oil. Except Baby as I don't yet know what to use on these engines. 3yrs my YV1000 had syntec as my cages & NKG's:clapper::clapper::clapper::clapper::cooldevil::cooldevil::cooldevil:
 
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