Iridium Spark Plugs... why or why not?

I've seen a lot of posts on here browsing the history, and a lot of conflicting people giving conflicting arguments.

They have a better spark, they're less prone to fouling, they're just long lasting and therefore useless, the XJ's are too irregular to have their benefits matter, they help make up for a weak stock coil, they're only useful on new bikes with advanced electrical systems, they're especially useful on old bikes with hesitant electrical systems, they're money well spent and you'll have no regrets, you might as well throw your money out the window, make sure you gap them, also be sure not to gap them, okay gap them but be careful. Also, don't gap them. No, seriously, gap them.

What are you running in your bike, and why is/isn't it an iridium plug? And if we could, let's try to minimize the anecdotes in regards to the benefits/issues with using these plugs. Please and thank you.

I'm sure you probably did feel a power increase and get better fuel economy and have your bike start better cold after replacing your old and worn out/fouled spark plugs with brand new iridium plugs. But unless you tested them back and forth with identical non-iridium plugs, that does little to help me (a complete and total newbie) figure out whether or not installing specifically iridium instead of OEM spec plugs at triple the cost would be worth the time and effort, and ultimately that's why I've come here tonight. Opinions are welcome, but if you have them, please do explain them.

 

Nothing fancy here- plain old NGK's.

 

AFAIK the point of iridium plugs is they last a long time. That's very important if you've got a car where you must partially remove the engine to service them. They're also nice if you want an 80,000 mile service interval.

 

I run whatever the engine came with originally. If its properly tuned and maintained, you shouldn't have issues. If you're putting in plugs that require less power to create a spark because of a tired electrical system, you're masking another problem. I have an old boat, a couple older bikes, and an old truck, no issues with any of them with standard plugs. Truck get's standard AC Delco's, Boat gets standard Champions, and bikes standard NGK. Wife's van came with Iridium originally, if I have it long enough it will get those.

I may be stubborn on the issue, but I feel there is no benefit to different plugs when everything else is correct.

 

last year i put them in my 750 seca, at the same time i de-coked the heads,lapped the valves, set the lash, freshened up the carbs, put in Dyna green coils, new copper wires and new fancy iridium plugs.
Did the plugs make a difference? Oh my yes, it starts easier, idles smoother, it's faster, gets better gas milage, it shines more, easier to wash, tires don't leak air anymore, the seat's more comfortable and the headlight's brighter.
Would i get them again? well shoulden't have to but if i coulden't get new ones i'd buy a used set from a bum under the bridge.
the bad part is the bugs on my teeth from smiling, thinking about my iridium plugs


too much coffee

 

I asked myself this question when i replaced my plugs and stayed with copper. i don't think i'll ever exceed the mileage benefits of the iridium plugs before they get too old. also i read that 'racers' use copper plugs because they are more efficient so i figure i just stick to copper.

 

Well. For me, every year I do my "regular" maintenance on my scoots. Change final drive oil, replace plugs, clean air filter(s), replace fuel filter, etc.

I figure I would be wasting money by staying "regular" with my schedule. For me, running high dollar plugs is just not worth it.

 

I have a standard plug in my wood chipper that has been in use since the mid 60's. Starts up every time I need to use it, and gives me 6 hours of working time per gallon. The plug gets cleaned and re-gapped every few years.

 

I can't seem to get the standard NGK BP7ES plugs here in London anymore - no one carries them, and no one will order them, and two places have told me NGK doesn't make them anymore (an obvious lie). I still have the original ignition coils, and (knock on wood) they're still going strong. I used to run the NGK BP7GPX (platinum) plugs -- those were excellent, and a great compromise between regular and the Iridiums. So of course they were completely discontinued a number of years ago.
This year I'm planning on switching to the NGK BPR6EIX Iridium plugs because that's what I can get locally everywhere. The single step heat range change shouldn't be a big deal, and I'll also be changing the plug caps for zero ohm versions, because the plugs already have resistors in them.
Should be interesting to see the results.

 

To the internet! <-- eBAY LINK

 

It's great how focused people are in actually answering questions. I was hoping for an answer. I have come to the conclusion that there is none!!
Now NGK standard CRE8 Plugs on my xj600 have lasted 1000 miles then 280 miles so I'm going iridium.
The extremes of opinion could be due to some bikes going better and others worse with iridium. Or it could be due....
However, unless one has the experience of someone with the same bike and set up I think one has to just fork out the money and see what happens.
As for why racers are supposed to prefer copper, have all racers been asked what they use?

 

There's really no reason to use iridium or platinum spark plugs in factory setup carburator engine, though you of course can if you want. Platinum spark plugs especially are easy to foul if you flood them with gas. (Changed about 1000 of those in military, our tracked SISU NA-140 trucks had rover 3.5l V8 engine tuned so rich that one of three trucks fouled plugs in every cold start even with preheating). For iridium I have used them in my Triumph Daytona as they are originals in that engine but can't see any real benefits you'd have there to gain.

 

When I had my 83 XJ650 Maxim it would not want to start once temperatures would drop to single digit degrees C with the standard NGK plugs installed. I replaced them with Bosch platinum I Dousman have any more issues with stats in colder temperatures

 

That's possible but original problem was never the plugs. If you have working engine with carburators in tune and coils etc in working condition it starts with the plugs it is designed to run with.

 

I use Honda CB750 coils and run Autolite 63 spark plugs which are replacement for NGK runs great , personally I would not buy Iridium spark plugs due to the extra cost .

 

Iridium is harder than copper, right? The electrode doesn't wear down and round off over time as much so maintains constant resistance. Obviously a plus but what's the price delta vs. OEM style plugs.

Assuming the fuel/air mixture is right an engine only needs as much spark as it needs to reliably fire the cylinder. Adding more spark energy/voltage won't improve efficiency, but will wear out plugs faster. Yamaha knows what they're doing and their ignition systems are pretty bulletproof.

A CDI box that fires multiple times per cycle might be kind of cool though.

 

Nickel NGK plugs cause they're like 2 bucks each

i just buy a bunch of them

 

Well now that just seems intentionally anecdotal

 

It might be. But then it's also imperically data-driven by decades of owning and maintaining old vehicles/equipment, Not to mention a good dose of solid electrical theory (as in the scientific kind).

The only difference between fancy "new tech" plugs and old plugs is how long they will go between cleanings, with the big variable being how much compression the cylinders run at. The XJ engine is of realtively low compression when eompared to most modern engines.

 

I had over 30 years of never seeing a spark plug fail. Oh I'd clean them now and again and even replace them when I could afford. And then three times in one year I had plugs die, so that I could still see them sparking when pulled out, but once screwed in under compression... Nothing. Previously I scoffed at the guys that would say "Change your plugs!".

Two of these episodes I can blame Yamaha machines also... A DT250 and a TTR230. I'm hoping for another 30 year streak of good luck now so I can get back to scoffing.