Iridium sparkplugs?

[firefighter]

Do you bother spending the extra on them? Is it really worth it?

Obviously my bikes getting a service.......i'm getting new plugs as I don't know when they were last done.

Is it woth spending extra on the iridiums or should I stick with the good old plain ones?

If it is worth spending the extra, what gains do I get to justify the price?

Also need some brake pads......

I'm wanting either Ferodo or EBC sintered HH pads......Which is your preference? (they're the same price roughly)

[Sidewinder]

Do you bother spending the extra on them? Is it really worth it?

Obviously my bikes getting a service.......i'm getting new plugs as I don't know when they were last done. Is it woth spending up on the iridiums or should I stick with the good old plain ones? I

just go with the factory ome ones, they cant be that bad if they put them in from the factory. unless ya wana rossi or biggles that is lol

[firefighter]

just go with the factory ome ones, they cant be that bad if they put them in from the factory. unless ya wana rossi or biggles that is lol

Lol. Nah, I just thought there would have been some sort of significant difference, at $10+ ea more expensive. Like smoother running etc.....

[vifferman]

From my research, they are worthwhile from the point of view that they basically don't wear out the electrodes like 'ordinary' plugs, so they'll last for years and years. However (but!) I've laso read (but can't validate this) that they are also prone to becoming unserviceable if they get fouled.

Don't expect any real change in performance or anything like that with them.

I had some in my VTR1000, just because someone else raved about them. Didn't notice any difference. I've now got some in my VFR, solely because they were only very slightly dearer (from Repco, amazingly enough!) than what I was quoted at Cycletreads for ordinary ones, and cheaper than what I was quoted for platinum-tipped ones. Cycletreads didn't have any in stock when I asked, Repco didn't either, but ordered them in and they were there in less than 2 hours. So, I figured it was worth it.

[firefighter]

I've now got some in my VFR, solely because they were only very slightly dearer

Awesome cheers for the info.

I take it the price difference was less than $10 per plug? (i've been quoted a $40 difference in the total price:gob:)

[bsasuper]

If the plugs are a pain to change in your bike like mine, they are worth putting them in.They are expensive -was quoted $48 each here, but picked up a set of 4 for $88 on ebay.

[vifferman]

Awesome cheers for the info.

I take it the price difference was less than $10 per plug? (i've been quoted a $40 difference in price:gob:)
From memory, it was $126 for four plugs. If you know what the standard plugs are, the iridium ones have a similar number but with an IX in it; for the VFR, the standard plugs were CR9EH-9, the iridium ones are CR9EHIX-9.

[Pussy]

I've got them in my sem fiddy.
I reckon the bike feels a bit chrisper with them... and they last for yonks!
Fit and forget!

[scumdog]

If the plugs are a pain to change in your bike like mine, they are worth putting them in.They are expensive -was quoted $48 each here, but picked up a set of 4 for $88 on ebay.

Yep, about the one real benefit of fitting such things.

[Hitcher]

I had a set of iridium plugs in my FJR for a while. I couldn't tell the difference between them and the stock NGKs.

[Henk]

Easier starting on two stroke dirt bikes. Other than that I wouldn't bother.

[Owl]

I can't believe the prices quoted, or maybe I just got a really good deal at $11.50+gst:D

They didn't fare too well in the triple though and I've since gone back to the stock CR9EK.

[bsasuper]

They wont feel any different, but they will last longer, the reason I use them.If you like to change out your standard plugs every 5000k, fine, me I dont.

[mossy1200]

I can't believe the prices quoted, or maybe I just got a really good deal at $11.50+gst:D

They didn't fare too well in the triple though and I've since gone back to the stock CR9EK.
I paid $90(4) for my FZR at part sponcership almost cost price so are we talking the same plugs or did someone put the wrong price against yours.

[slowpoke]

Depends why you are considering them.
If it's for performance a better option might be to go with (from memory) NGK CR9EK's. They are "ordinary" plugs but extend slightly further into the combustion chanber, thereby slighty increasing the compression ratio which equals cheap power. It's not much but it's cost ya absolutely nothing if you were going to change the plugs anyway.

[Owl]

I paid $90(4) for my FZR at part sponcership almost cost price so are we talking the same plugs or did someone put the wrong price against yours.

Who's cost? These plugs (CR9EIX) retail in the US for about $11 and can be purchased as low as $7.40 ($10.70NZ)

Perhaps the price was wrong or maybe someone here is making a killing!:whistle:

[Bonez]

Who's cost? These plugs (CR9EIX) retail in the US for about $11 and can be purchased as low as $7.40 ($10.70NZ)

Perhaps the price was wrong or maybe someone here is making a killing!:whistle:Typical NZ 300% markup I would imagine. Anyway I normally get over 30,000kms out of a "standard" set of plugs, is that good? Or am I doing something wrong......

[Henk]

Depends why you are considering them.
If it's for performance a better option might be to go with (from memory) NGK CR9EK's. They are "ordinary" plugs but extend slightly further into the combustion chanber, thereby slighty increasing the compression ratio which equals cheap power. It's not much but it's cost ya absolutely nothing if you were going to change the plugs anyway.

Unless they extend a little too far and end up smacking into the piston.

[Owl]

Depends why you are considering them.
If it's for performance a better option might be to go with (from memory) NGK CR9EK's. They are "ordinary" plugs but extend slightly further into the combustion chanber, thereby slighty increasing the compression ratio which equals cheap power. It's not much but it's cost ya absolutely nothing if you were going to change the plugs anyway.

The CR9EK's are not ordinary plugs as they have dual electrodes.

[slowpoke]

Unless they extend a little too far and end up smacking into the piston.

Like no-one would have thought of that.....they aren't 50mm long for fucks sake. Open valves protrude faaaaar further into the chamber than any spark plug.


The CR9EK's are not ordinary plugs as they have dual electrodes.

What is this, a meeting of the Anal appreciation society? It's a conventional plug, with conventional electrodes (albeit 2 of them) rather than iridium or surface dischage etc bloody etc.

[SS90]

Like no-one would have thought of that.....they aren't 50mm long for fucks sake. Open valves protrude faaaaar further into the chamber than any spark plug.





Not quite!

As the piston comes to TDC (let's chose the compression stroke here), the inlet valve closes JUST before the piston gets to the top.

On a "tuned" 4 stroke engine, you would expect 30 thou "piston to valve clearance", that is, there is 30 thousands of an inch CLEARANCE between the inlet valve as it closes (or the exhaust valve) as the piston comes up to TDC.

On such an engine, at TDC there is often only 2mm between the crown of the piston and the spark plug electrode.

Particularly when you have "high compression" pistons (raised dome)

That isn't much at all. (less that 1mm)

More expensive stuff has even tighter clearances.

With that in mind, on a performance engine, it is quite possible to chose a plug that is too long, and have it touch the piston (particularly at high RPM)

Quite often if you modify an engine (i.e remove material from the head to increase compression) you have to find shorter plugs that have enough clearance.

The majority of "day to day" stuff has big safety margins, but as the consumer demands more and more power, things like this become part of the equation when servicing your bike.

30 years ago, this was not a problem, because the engines where so often "low spec" that the valves could be completely open, and still not touch the piston.

Of course, these days are long gone!
Simply put, cam lift and duration go longer, RPM got higher, and engines became more fragile.

[vifferman]

With that in mind, on a performance engine, it is quite possible to chose a plug that is too long, and have it touch the piston (particularly at high RPM)
Isn't that because the conrod can actually stretch a minute amount?

[Owl]

What is this, a meeting of the Anal appreciation society? It's a conventional plug, with conventional electrodes (albeit 2 of them) rather than iridium or surface dischage etc bloody etc.

Apologies slowpoke! I see now what you were getting at.;)

[dipshit]

just go with the factory ome ones, they cant be that bad if they put them in from the factory. unless ya wana rossi or biggles that is lol

Iridium plugs are factory OME in K8 600/750 GSXR's

[firefighter]

I can't believe the prices quoted, or maybe I just got a really good deal at $11.50+gst:D

They didn't fare too well in the triple though and I've since gone back to the stock CR9EK.

Where did you find these? Ebay U.S did'nt show these same prices.....(either that or the shipping was what fucked it)


I paid $90(4) for my FZR at part sponcership almost cost price so are we talking the same plugs or did someone put the wrong price against yours.

Geez dude. I just bought some (4) today from Ebay U.K for $82 including shipping......evidently $2 more than the cheap ones were going to cost.
I have to put the service back a couple of weeks while I wait but it's worth it for the sake of $2 and getting the best.......

Now I can use the spare $40 I have to go towards the front brake pads I need to replace and get EBC sintered HH pads instead of the cheaper ones! (unfortunately I could'nt find a reasonable discount online to make it worth importing them so full shop price)

[Owl]

Where did you find these? Ebay U.S did'nt show these same prices.....(either that or the shipping was what fucked it)

Local and at mates rates.


I have to put the service back a couple of weeks while I wait but it's worth it for the sake of $2 and getting the best.......

Apparently Denso Iridiums are the best, but substantially dearer.

[quickbuck]

However (but!) I've laso read (but can't validate this) that they are also prone to becoming unserviceable if they get fouled.



Interesting....
That piece of literature is worthless.

Aircraft run Iridium Plugs (they are able to run non-iridium too)... and we service the plugs all the time... Fouled ones clean up easily.
Slight difference in construction though, but shouldn't make a difference.

[mossy1200]

Where did you find these? Ebay U.S did'nt show these same prices.....(either that or the shipping was what fucked it)



Geez dude. I just bought some (4) today from Ebay U.K for $82 including shipping......evidently $2 more than the cheap ones were going to cost.
I have to put the service back a couple of weeks while I wait but it's worth it for the sake of $2 and getting the best.......

Now I can use the spare $40 I have to go towards the front brake pads I need to replace and get EBC sintered HH pads instead of the cheaper ones! (unfortunately I could'nt find a reasonable discount online to make it worth importing them so full shop price)

I got mine when the exchange was around 55cents to dollar so that would have made some difference.DPR8EIX-9 was $13usd each at the time retail plus freight so I thought $90 was fairly good.

[slowpoke]

"Many a truth is said in jest" but who would have thought the truth could be so scary........

[jono035]

Isn't that because the conrod can actually stretch a minute amount?

I remember working out how much a conrod changed in length in high school with the help of my physics teacher.

Steel elongates (strains) when exposed to stress according to its modulus of elasticity...
Found some conrod data (AISI 4340) that says it has a modulus of elasticity of 205GPa.

Modulus of Elasticity = stress divided by strain.
Strain is change in length over original length.
Stress is the pressure the material is subjected to (force divided by area)

Yield strength is 786MPa which corresponds to a 0.3% change in length just before the material deforms permanently.

On a 100mm long conrod that is a 0.3mm change in length...

That is a lot less than I would have thought, but then again that is a performance conrod, a factory one would probably be a lot worse.

[NighthawkNZ]

Do you bother spending the extra on them? Is it really worth it?

I asked the mechanics at Advanced Motorcycles that the other day...

He said unless you are racing not worth it, you won't really notice it unless you have had other things done to the bike etc... you will be paying twice as much for no real extra anything...

[The Stranger]

I had a set of iridium plugs in my FJR for a while. I couldn't tell the difference between them and the stock NGKs.

There should be no difference in performance, only in longevity.
As noted if they are difficult to get at, go the iridium's. But also the plugs in a bike are working way harder than a car in general. How many cars rev to even 8,000 rpm, let alone sit there all day at that figure?

Not sure how many cars run a redundant spark these days but quite a few bike motors do, which may add even more work for the plugs.

[AllanB]

Spark Plugs - service book says don't even have a look at them for 12,000 kms. Replace at 24,000 when the head gear gets checked for the first time.

Modern engines are good. :woohoo:

[AllanB]

Which makes me wonder - how come the engine does not need anything looking at for 24,000 kms - apart from regular oil & filters before that period, nothing really gets touched.

So the days of torquing the head etc early on are long gone - how come? Better materials, better machining etc I presume.

[SS90]

On a 100mm long conrod that is a 0.3mm change in length...

That is a lot less than I would have thought, but then again that is a performance conrod, a factory one would probably be a lot worse.

It's fairly well accepted that an engine revving to 12,000 RPM would see an approximate stretch in the connecting rod of (up to) 0.5mm

That is why on some performance two strokes (with a cylinder head/piston clearance of 1mm) will show signs of touching the head occasionally.

Sadly, if a valve touches the piston on a four stroke the damage is quite serious.

Which is why, as you point out modern 4 strokes tend to have expensive rods, and lately more engines comes from the factory with Titanium valves (which resist stretching better, BUT work harden, and require replacement far far more often than Crmo valves of old.)

[imdying]

He said unless you are racing not worth it, you won't really notice it unless you have had other things done to the bike etc... you will be paying twice as much for no real extra anything...They do last longer; they spec them on cars with plugs that are difficult to remove so that there's little chance of having to replace them under warranty :laugh: (sad but true)

On a two stroke they're golden, I get plenty of extra kms out of them on those... probably not enough to justify the $/km, but it's worth paying the premium to not have to change them as often. Admittedly I try never run a two stroke in a 'bad' state of tune, but I have noticed that I've never had one foul on me. I'll also admit that I've never had a standard one foul though... but I don't leave them in till they're buggered either.

[vifferman]

Interesting....
That piece of literature is worthless.

Aircraft run Iridium Plugs (they are able to run non-iridium too)... and we service the plugs all the time... Fouled ones clean up easily.
Slight difference in construction though, but shouldn't make a difference.
Yeah, it sounded kinda bogus to me, so given that there was no reference to any real data, I gave it the credence it deserved.
But thanks for that! :niceone:

[FastFred]

Not quite!

As the piston comes to TDC (let's chose the compression stroke here), the inlet valve closes JUST before the piston gets to the top.



Not quite

Actually both valves are closed when the piston comes to TDC on the compression stroke.

On the compression stroke the inlet valve closes a little ABDC thats after bottom dead center.

On the exhaust stroke the inlet opens a little BTDC and the exhaust valve closes a little ATDC

Its the exhaust valve that gets hit by the piston. Because at high rev's it can be to slow getting out of the way.

[SS90]

Not quite

Actually both valves are closed when the piston comes to TDC on the compression stroke.

.

Oh yes, I meant "overlap", not "compression". (sometimes referred to as "both valves rocking")

But, the inlet valve can indeed be hit by the piston, as the "overlap" phase denotes the time between the exhaust valve closing, and the inlet valve opening.

The piston comes up to TDC, the inlet valve is opening, and the exhaust valve closing. Both valves are open, (only just) as the piston come to TDC

That is why you check both valve clearances at TDC compression.

At high RPM, situations exsist where the valves (inlet or exhaust) can hit the piston.

It depends on the duration of the cam in question (inlet or exhaust)

Particularly now that 4 stroke engines rev so high.

This is why you measure your "piston to valve clearances"

Ask Thomas. (Toot Toot)

[insane1]

keep away from sintered pads they will chew discs real fast,try ceramic pads.

[vifferman]

keep away from sintered pads they will chew discs real fast,try ceramic pads.
Really?
Even though ceramics are almost always harder'n than many metals?
And (AFAIK) sintered pads are just a mixture of glue and metal fibres?

[Ixion]

Wouldn't bother on a four stroke. Doubtful on a two stroke. I've tried just about every 'fancy" spark plug ever. Unconvinced that any of them were worth the extra money.

[Blackbird]

Iridium plugs are standard on the 'bird and I changed them on the advised schedule at 60,000 km. Needn't have bothered as they looked perfect and the gap hadn't changed. Some of the UK 'bird owners don't bother until 100,000 km!

Oh, and sintered pads don't necessarily cause a high wear rate - depends what the sinter medium is. The EBC HH pads I fitted are copper and they are pretty kind to rotors. I think you'll be impressed with their stopping power. I certainly am compared with the SBS ones I had in previously.

[insane1]

sbs sintered pads stuffed my rear disc it"s only done 38,000 kms $210 later brand new ebc disc .

[jono035]

sbs sintered pads stuffed my rear disc it"s only done 38,000 kms $210 later brand new ebc disc .

As per usual there are probably 40 or 50 different variables at play here so saying 'such and such stuffed my discs' is probably a little disingenuous...