Do Irridium plugs make any difference

[Northern Monkey]

Other than costing £6 each instead of £2, is there any difference between the 2, or is it just marketing BS?

[DrSnoosnoo]

My car mechanic mate says he uses them purely for the longer life, they'd last 2 years instead of 1 for example. I bought some for my zzr but then the zzr community told me that there is an unknown reason that makes the bike run completely shite with them in.
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I'm Sam; Northern, Ginger, Lover
Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

[lihp]

Iridium plugs are just for longer life and that is all.

[Scotsman37]

https://www.globaldenso.com/en/products/aftermarket/plug/qa/iridium/images/p6-1.gif

https://www.globaldenso.com/en/products/aftermarket/plug/qa/tough/images/p21-1.gif

https://www.globaldenso.com/en/products/aftermarket/plug/qa/tough/images/p11-1.gif

As they previous person stated they are designed only for longevity and also shown in the pic, but as you can see from the guide from Denso makers they even use slightly less energy to ignite fuel due to its design no doubt making it easier to start the bike from a stone cold engine meaning slightly less of a drain on the battery in a cold climate - I think?

Further info about spark plugs

https://www.sparkplugs.co.uk/pages/manufacturer/about-ngk-spark-plugs.htm

[Rogerborg]

I convinced myself that I got slightly better cold starting with an iridium plug in my 125. Probably delusional though.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[LaurenceR46]

They last for a really long time so it makes sense as they are not easy to get to on a lot of bikes. They seemed to perform a bit better on my 650F.

Great plugs I say.
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Yamaha R6 (R46) Rossi Replica Edition

[Snorty]

[Baffler186]

I remember another thread on iridium plugs - something about cleaning them (i.e. don't clean/scrub the ends becasue you remove the iridium coating and have just converted your expensive plug into a normal plug).

That said, I've never used them myself.
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Current: 2009 SV650 S, 1990 Kawasaki GT550
Previous: 2009 CBF125, 1998 GSF600, 2004 FZ6 Fazer, 1978 CB400a Hondamatic

[ws4936]

The ZX6 has always had them.

Great if you 'forget' when to change them by the books mileage. Definitly gives you more leeway.
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If everything seems under control, you're just not going fast enough.

[LaurenceR46]

Yes, don't clean iridium plugs you'll remove the thin coating. To be fair the only sparks I have had to clean have been in my 2 stroke mini moto!
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Yamaha R6 (R46) Rossi Replica Edition

[Bubblin77]

Copper is a fantastic conductor, much more than the iridium coated crap, a new, properly gapped copper electrode will fire more accurately than the same in an iridium tip.

Iridium however doesn't wear as quickly as copper so the spark will remain more consistent for a given tip style.

Here's the crux, the finer and more sharp you can make the tip of an electrode the better the spark you will get, but that tip will wear quickly, hence if we had a fine copper tipped electrode it's would be good, but would breakdown within a few hundred miles. And the reason why the poor conducting iridium can be used, so its quite a trade off.

As long as your compression isn't too high, then a copper pointed electrode, gapped and tip reshaped every few hundred miles will win out, although iridium is far easier to maintain a good strong spark.
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Kawasaki Z800 (SOLD)

[map]

If I had a hard to work on bike with difficult to get to plugs (e.g VFR750) then I'd fit iridium plugs.

When riding it does give you a superior sense of using the latest technology, copper is so 20th century
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...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
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[kramdra]

[Bubblin77]

[temeluchus]

[Bubblin77]

Which is what I've said

IF

We have a centre conductor that's pointed smsnd sharp one made from copper and one coated in iridium, the copper one would fire more efficiently and require less from the electrical system than the iridium coated one.

But the copper would break down very, very quickly.

So its a catch 22, do you use copper which has far higher electrical conductivity but wears quickly or do we use iridium coating, useca very fine tip and the benefits of a sharp edge?

If I wanted best performance, a copper fine tipped plug, changed every 100 miles would be my choice, but as I'm lazy and poor I'll go with the latter or just a standard plug.
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Kawasaki Z800 (SOLD)

[temeluchus]

[temeluchus]

[MattEMulsion]

They also add approximately £500 to the selling price of a bike because "its got iridium plugs init bro"...
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Yamaha YZF-R6

[Fizzer Thou]

I have iridium plugs fitted to the R1 and the KTM enduro and they made a differance to throttle response.

But on the Exup1000 I fitted gold-paladium plugs and it made a similar differance.

And at £2.50 per plug (Maccess) then they were worthwhile
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Just talk bikes.What else is there?

Always have a 'Plan B'

[Teflon-Mike]

A 'better' spark? In what way 'better'?

The spark sets the fire in the hole.
The Ignition Timing device tells it when.

I spent a term at uni with a Recardo Test Engine, polishing a perspex piston, playing with mixture strengths and ignition timing, measuring fuel consumption and brake force; and watching high-speed camera footage of the flame patterns in the pot.....

This is 'Tuning'.

Playing with all the different variables to find the 'optimums' where they work best 'Together'... and THAT is the key here. Make a change in isolation, and it's likely to screw the optimums, and make stuff WORSE unless you adjust all the other variables to find a new optimum for the variable you just changed... and even then, likely not to make anything 'better' overall, just shift the compromise around some-where.

The one saving grace of 'Performance' spark plugs, is that in all likelihood, they don't change fuck-all, and save the optimisation manufacturers have invested thousands of lab hours, or, these days, a few million computer-simulations, and a few hundred lab-hours arriving at!

A 'better' spark plug, shouldn't help 'find' any more power, any more economy, any more throttle response, or any 'easier' starting.

Any gain in spark energy from having greater conductivity... well, for a start, such a gain is going to be pretty small, tending to insignificant, but, even if it were as huge an increase as presumed, difference it would make to the engine performance is negligible.

The 'flame-front' is where burning charge sets fire to unburned charge next to it. Imagine a candle; you set fire to the wick, the flame moves down the candle as its burned away, I dont know, maybe an inch an hour depending how fat the candle is. Same thing happens in an engine.... just a lot faster! BUT, how fast the flame-front travels is pretty much a constant, fixed by the 'rate of chemical reaction' for turning fuel into CO2.

So your spark creates a 'fire ball', but it is absolutely tiny. Maybe, the size of a pin-head. Area of a sphere is 4/3Pi r2, volume, 4/3Pi r3.

And as the flame front progresses, R will increase at an 'almost' fixed rate, but, the area of flame front, will increase at 4x the square of that speed, the volume of charge burning, increasing at 4x the cube of the flame speed.

Its a bit like, the rice on the chess-board fable; if you place one grain of rice on the first square of the board, two on the next, four on the next, eight on the next and so on, doubling the number of grains of rice each time... how many squares will you have covered before a 50Kg sack of rice is empty? From memory, its something like the first two rows; by the 64th square you need something like all the rice in China, enough to cover the UK by to a depth of about six inches or something daft... but no matter... WE have finite amount of rice, one sack. And doubling the rice on each square, we run out after 16 squares.

So, start with two grains of ride on the first square instead of one... double the amount of fuel set on fire by your spark.... you run out of rice after 15 squares...not 16... doubling the initiator, lifts the start point one increment, it doesn't double the rate of exponential growth.

A better, bigger spark, then WONT burn your charge any faster... that's fixed by the rate of reaction. Wont burn you any MORE charge; that's fixed by the displacement of the cylinder.

At the VERY best... a bigger beefier spark, will merely increase the initial size of the flame front at point of initiation... and as that increases on an exponential, it will be incredibly insignificant to the overall combustion efficiency. We are talking one grain of rice in a 50Kilo sack difference!

That's the 'best' difference a better spark plug might achieve.... fuck all in real terms.

SO, unless you have built a hi-po motor and changed all the other variables and need to find a new optimum around them.... the only 'advantage' a better plug might offer is stability.

Plugs don't 'wear out' they are pretty much an inert device... yup, they errode... but take one out the pot, you can still get a spark from it, clean the electrodes, re-gap it, shove it back in.... might be a bit degraded from less sharp corners... BUT... the ability a plug has to effect anything, as explained is pretty bludy negligible.

So at best, all a 'performance' spark plug CAN do, is maintain the electrode gap within tolerance better, over a longer period of service.

Any benefit allegorically reported by buyers, is as likely to simply be from replacing a fucked old plug in a tired old engine with a nice new one, at the same time that tired engine gets a service, NOT from the miracle properties of snake-oil spark-plugs!

And on re-tuned engines? Well, again; its a spark plug. Its ability to 'enhance' engine performance is incredibly limited. If the ECU has been re-mapped to re-optimise fuel mixture and ignition timing? Its POSSIBLE that a different plug might be required, possibly with a different gap, to complete the new optimisation... but again... any 'improvement' found from such re-optimisation is likely to come from shifting the compromises in the engine map, NOT from the plug, and just as likely that a conventional plug of a suitable heat grade and gap would show the exact same improvements.

Buy them if you wish.... but its a bit like sticking a gold plated phono-plug on a pair of Pound-Land ear-phones, hoping for Sennheiser sound quality.... the Plug simply isn't the weakest link, and has little influence over the system as a whole to be able to make such a huge difference.
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
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[lihp]

Totally irrelevant Tef, and where did you actually answer the question?

Additionally you're finally analogy of gold plated connectors is inaccurate, as gold is a relatively poor conductor, and is only used to prevent connector wear from repeated connections.

[Bubblin77]

TEF, if the quality and size of the flame doesn't matter how come Ferrari fit spark plugs with the open side of the plug facing the chamber of the cyclinder, and why toyota sell different plugs for different cylinders so the spark plug sparks in a different place to get maximum effect.

People also rotate the plug using different thicknesses if shims to alter power within the cylinder
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Kawasaki Z800 (SOLD)

[parkmoy]

Anecdotal evidence I know but when I had a 125 marauder I fitted an irrdium plug and I swear I got better performance from it. Might just have been a following wind though

[Teflon-Mike]