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Iridiums??? Is there a point???

Discussion in 'Bling and Appearance' at netrider.net.au started by fingers89, Feb 18, 2008.

  1. Hi all,

    I have been told by a couple of mates in the mechanics trade that iridium sparkplugs dont give any performance increase whatsoever, that they are only useful for long lasting applications, which due to my bikes (250 bandit) high revving motor are relativly uselss anyway. I can see why my friends believe what they do, but i wanted some other opinions.

    Another friend said they are uselss in a small displacement motor and are only good in a car size engine, and larger bikes i.e +600cc.

    Any ideas are welcome.

    P.S due to my job, i can get cheap iridiums, (25% off)

    thanks again fingers89
  2. That's what I've been told too.
  3. I do have confidence in the people who told me these things about them, but why bother labelling them as a performance plug if they arent. i have a mate who used to have a high 7 second drag car, and all he ever ran where standard ngk plugs.

    another thing that i heard is that because of their tip, they can make bike motors pind, but again im not sure how true this is.

    Any help would be appreciated.
  4. Yep. The advantage of iridium plugs is the fact the tip is narrower which means lees energy is needed to create a spark - but this smaller mass also means less heat is absorbed so the chances of pre-ignition can increase (unless you use a cooler plug). The more serious problem though is that if pre-ignition does occur it can knock the extremely hard and brittle iridium tip from the plug - which can cause massive amounts of damage to the engine. Performance can be improved with iridium tips - but it's more something that's noticeable on 500+hp race cars than on a 40hp 250. Of course copper plugs have the advantage of being cheaper and usually available in a greater range of temperatures which can make it easier to get an engine running perfect.
  5. I believe Iridiums are mainly designed for long life purposes, for use in some cars which,incredibly, require things like the inlet and/or exhaust manifold to be removed in order to gain access to the plugs.

    For this reason they are supposed to last 70-80,000 km or more.

    That's a different kind of performance to what you are seeking!

    Basically, a spark plug of the same heatrange, length, projection and tip design will work the same as any other of that type. The only performance gain anyone is likely to see when changing plugs is if the old ones were extremely old, the new ones might, just might, show a slight performance improvement.

    Or to put it another way, changing spark plugs does not, by itself, give you a performance improvement.


    Trevor G
  6. Platinums were the ones designed for long life - iridium does offer an advantage of having a much smaller tip and were developed for racing (specifically F1 which still uses them). But definitely a waste of money for the average person IMO, if you want long life go for platinums, otherwise copper works just fine.
  7. I put iridium plugs in mine, but not for the performance. It starts much easier and the different is especially apparent in cold weather.
  8. How old were the copper ones you replaced?
  9. good.

    Now i dont feel dumb, cause at work i always tell customers not to bother with iridiums (mainly people with wrx's and the like) to not bother with them. I dont like my work very much. lol. So it is good to know that for myself there is no advantage, cause im looking for a little bit more poke, and im trying to find a cheaper way to do it.

    cheers. fingers89
  10. Just make sure you change the plugs often, the 250 bandit engine will chew through them at a fairly rapid rate. I used to clean/inspect the plugs every 2,500kms or less, replaced them every 5,000kms. Not that difficult to do or expensive if using copper plugs (buying in bulk makes them cheaper still) and it kept the bike running perfectly.
  11. Yeah im kind of handy with a spanner anyway, and i do change 'em myself every 5-6000 km. I recently changed them and the bike seems to be getting better fuel economy.

    cheers fingers89
  12. Thanks for reminding me lads, it's 20,000km since I did my plugs last, perhaps that's why the bugger's having trouble hot starting.
  13. Brand new standard vs brand new iridium.

    Used the standard ones for a few weeks then got some iridiums for v cheap from ebay. The iridium ones start much better. You can make up whatever you want for not getting these, but they are higher quality, do burn cleaner and will last longer - as long as you're using them for the right reasons. Performance isn't a reason.
  14. Hmmm I think it's time I changed mine as well... What's a good price for these iridium plugs? I think I might give them a shot! :wink:
  15. Performance was the reason they were invented - the lower voltage requirement allows for higher compression ratios (if I remember right air resistance increases with increased pressure). They just don't make much of a performance difference to normal vehicles (unless you've increased compression or fitted a high boost turbo).
    Improvements in running come down to the smaller tip being less likely to foul - but if the copper plugs were having that problem then it's usually an indication of a problem elsewhere (ie tuning or riding style). Fitting iridiums might fix the symptoms but doesn't necessarily eliminate the cause.
  16. :p Hope not, just fully serviced and rejetted :LOL:

    Putting them in for performance on 'nonmodifiedtobuggerycrazyhp' vehicles would be pointless imo. They do have other uses which includes cleaner and easier starts, which is what I use them for..
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  18. So you charge your customers for changing good plug?

    At least with iridium plugs you can save yourself the time of removing the tank, and everything else needed to get to them, just to check.

    Put in at 30thou...still in without a miss at 85 thou. That's in the A1 1000GTR.
  19. Well i can get them for around $15 a plug, but most people will pay $18-$20 for 1 plug. they are very expensive. Also i can only get mine at work (supercheap auto) but i dont have them for my mates bike, you'll have to go to a bike shop to get them , so u may pay more per plug.

  20. Yeah or you can ebay them for about 8 bucks a plug + postage