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I have a set of NGK Iridium spark plugs in my VN750 with 18,000 miles on them. The engine still starts right up and runs good. When do you guys eventually replace the NGK Iridium plugs????? :) My bike is a 2006 with 32,000 miles on it.
 

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As long as it's running good I wouldn't worry about them. Just check them every now and then. I also have about 18,000 on my set. I pull them every 3 or 4 thousand just to take a look, nothing ever found and really shouldn't be it your mixtures are set correctly and no engine problems. I'm thinking they are going to last 50-75k or so, maybe more.
 

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KM is cheap lol
may be JM ... but I bought iridiums and put them in mine partially because I think he's right! :smiley_th
 

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Well 75k is real close to never, isn't it? :)
 

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I see no reason to replace ANY brand or type of spark plugs as long as the bike is running good, starting good, and gas mileage is still normal. These things will change when the plug gap gets too big, then it's time for new plugs. But, if you use NGK plugs, they are cheap enough to replace once in a while just to make you feel better, if it does. I'm a little unhappy about having to replace 4 plugs in a 2 cylinder engine, when other 2 cylinder engines run just fine with just 2 plugs. It doubles the cost, and for nothing. However, I am happy the Vulcan's plugs are easy to change, some motorcycle plugs are almost impossible to get to. The Suzuki Savage requires removal of the seat and tank to get to the plug. But at least there is just one. Try changing the plugs on a '93 Kawasaki ZX11. It takes half a day.
 

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I have a set of NGK Iridium spark plugs in my VN750 with 18,000 miles on them. The engine still starts right up and runs good. When do you guys eventually replace the NGK Iridium plugs????? :) My bike is a 2006 with 32,000 miles on it.
Iridium plugs last longer than other plugs, but the electrode tip will eventually 'round over'. That's when the plug's performance starts to degrade. For my Subaru Outback that happens at 30K. Not sure about the VN750, but check the electrode tip; is it still square (good) or rounded over (bad)?
 

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I have NGK platinum plugs in my 1992 Olds 88 that have been in there for at least 11 years and close to 100,000 kilometers, (60k miles), and they show no wear. I`m going for 100k miles on them.:smiley_th
 

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That was what I was alluding to. I'll likely sell my bike before I have to change the plugs. And that ain't being cheap, that be being smart.;)
I change mine every other season,usually between 16-18000 miles. I think that's being smart for optimum performance. :smiley_th
 

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How much better is the Iridium plug versus a new, regular NGK?

P.s.-I dont think any spark plugs were harder to change than the ones on my Camaro with the LS1. haha took about 8 hours. lol
 

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I have NGK platinum plugs in my 1992 Olds 88 that have been in there for at least 11 years and close to 100,000 kilometers, (60k miles), and they show no wear. I`m going for 100k miles on them.:smiley_th
I replaced a set of AC/Delco Platinum plugs in my camaro a few months ago. they had ~100,000 and were pretty nasty looking. (Clean, but deteriorated) The Iridiums should last 100k easy. I replaced mine with AC/Delco iridiums.
 

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may be JM ... but I bought iridiums and put them in mine partially because I think he's right! :smiley_th
Maybe yes maybe no. All Iridiums are not created equal. Denso has a single iridium ( plug type) used in our bikes that has a .4mm elecrode. They recommend changing plugs at 60,000 for cars and 20,000 for motorcycles. Most of the other manufactures have a .6mm and a .7mm electrode. For a 6mm single iridium they say 60-90000 in cars. For Iridium/platinum combination they say 90-120,000 miles in cars. Some new iridiums have .7mm electrode and iridium/platinum combination for 100,000-120,000 miles in cars. All these mileage figures are for cars ( except Denso ). Motorcycles because of their higher rpms and higher running temperatures get way less miles out of any plug compared to a car, 66% less in Denso's recommendation.
 

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^ First off we are talking about NGK plugs. See the title heading? Don't give a crap about any other brand cause I would not use them ....lol

And I guess you haven't seen me drive. ;) I'm likely harder on mr cars plugs than my bikes. Couple that with the Vulcan that uses two plugs per cylinder and I bet my car would go through a set of iridiums faster than most of you on your Vulcan.

Motorcycles don't all run hotter than cars or really at higher rpms unless that's what you do all the time. I know my neighbor says he rarely goes over 4000 rpms on his Goldwing. So please don't make generalizations.

cglennon pointed out that when the tip gets "rounded off" that's a good time to replace your plug. This is true of any type of spark plug. Theorizing how many miles you will get out of your iridiums depends so much on each bike it's pointless to start guessing. I do think replacing them every 16-18000 miles is likely just a waste of money.
 

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I guess everyone has to decide for themselves what being 'smart' is. Even at $7 a plug (and replacing 4), the iridiums seemed like the ticket. I pretty much bought in to the sales pitch, and when I installed them, I was a believer. Seemed to help on hot restarts.
If I get 60K miles out of them, that's probably more miles than I'll put on the Vulcan. I'll pull them regularly just to check combustion performance, and check the tips for sure. In the mean time, I'll also benefit from a more energetic spark for more reliable ignition and even flame front in the burn.
I don't mind the redundancy of the two extra plugs, I see it as added reliability. If you think they are there for no reason, unplug two of them, you can regain some wasted amperage, and cut the cost of plug replacements in half. But let the rest of us know if you also notice any performance/efficiency loss.
No matter the mileage, I'm all in and committed to my iridiums. If they wear, I will replace them with the same or better. :beerchug:
 

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I'm a little unhappy about having to replace 4 plugs in a 2 cylinder engine, when other 2 cylinder engines run just fine with just 2 plugs. It doubles the cost, and for nothing.
Well that used to be my thoughts exactly, till a friend and I had the wires off a plug on each Cyl. ... We were trying to figure something out about the socket to fit in the wells or something (CRS)... Anyway later about 5-6 of us went on a group ride and going up Sewanee mountain my bike just didn't have near the gitty up go it should have, we made a rest stop at a little roadside table on over the Mtn. and I mentioned that my bike just wasn't running like it should, someone said that it might help if I put the plug wires back on...lol...there those 2 wires hung, we had not put them back on... I put the wires back on and Clyde sung a very happy song...
So, that would be an easy find out, just remove a wire from each Cyl. and I think on the VN750 you will see the difference, I know it sure changed my mind...
Have a good one...Old Dog...
 

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^ First off we are talking about NGK plugs. See the title heading? Don't give a crap about any other brand cause I would not use them ....lol

And I guess you haven't seen me drive. ;) I'm likely harder on mr cars plugs than my bikes. Couple that with the Vulcan that uses two plugs per cylinder and I bet my car would go through a set of iridiums faster than most of you on your Vulcan.

Motorcycles don't all run hotter than cars or really at higher rpms unless that's what you do all the time. I know my neighbor says he rarely goes over 4000 rpms on his Goldwing. So please don't make generalizations.

cglennon pointed out that when the tip gets "rounded off" that's a good time to replace your plug. This is true of any type of spark plug. Theorizing how many miles you will get out of your iridiums depends so much on each bike it's pointless to start guessing. I do think replacing them every 16-18000 miles is likely just a waste of money.
LOL He did say NGK plugs. But are we talking about a manufacture or are we really talking about IRIDIUM, the metal ? Also, how many cars are running down the road pulling 4500-5000 rpms at highway speed? And most bikes do run hotter than cars. :hitanykey
 

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My bike is running at 2800 rpms at 70mph. My car is running at 2300 rpms at that speed.

My bike uses the same thermostat that many cars do. The radiator on my bike is bigger than my car. ANYONE making a water cooled bike designs it to run at a maximum tempature, same as a car.

I'm sorry your bike runs hot. And we were talking about NGK Iridium plugs here....so the answer to your question is "both". There's another thread talking about off brands I think.

"most" is a generalization. Perhaps you can do a survey and prove your right?

:)
 

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4000 rpm on a new 1800 Goldwing is about 100 mph. My old 1200 turns a lot faster. The Goldwing (new and old) has what is basically a car motor, and runs about the same temperature. The big difference in running temperature is between liquid cooled bikes and air cooled bikes. Liquid cooled bikes run cooler, and maintain more even temperatures.

As for cars, a big V8 is going to be a LOT easier on plugs than a small high revving 4 cylinder. ANY stock small block Chevy will go 100,000 miles on one set of good plugs, unless it is burning oil or running rich. But those two conditions will ruin plugs in ANY engine.
 
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