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Iridium Spark Plugs

Discussion in 'Technical and Troubleshooting Torque' started by craigrider, Jan 5, 2010.

  1. So got the bike a couple of months ago (2000 bandit gsf250v).. and in the process of replacing all the consumables that you just don't know how long its been since replacement..

    Got round to the spark plugs and looked at standard NGK and Bosch, (~$4 ea) each decided after a bit of research and my personal opinion that spark plugs have a tough life in a bike vs a car ( running at 3 times the rpm on average in a 4 pot screamer like mine) I splashed out on some NGK iridium spark plugs ($17.40 each!)


    And the difference is phenomenal!! which is amazing since the ones i pulled out were in good nick (good gap not corroded) and didn't look that old at all.. On the old spark plugs I was getting a large flat spot under acceleration in the lower revs particularly when it was cold.. was really annoying me when i have to accelerate out onto the main road as it would hold up my acceleration.. Now with the new ones there is no flat spot at all! :dance:

    Just thought id share this for any of you who are trying to decide if the more expensive spark plugs are worthwhile.. I will be using them in the future!



  2. Yep, I had a set in the Hornet for a couple of years, they DO make a difference, it just takes a few weeks to kick in if you put them in not-new bike. A dumb mechanic at a new place I went to took them out and put new plugs in, and I never got round to getting a new set (which I probably should :roll:)
  3. Just curious here.

    Are they basically just plug in and play or do you need to retune carbs for maximum benefit? The advertising seems to indicate they can fire with leaner mixes so wondering if you don't re-tune whether you are running rich?

    Also Hornet, why does it take a a few weeks to kick in on an older bike?
  4. The results were instantaneous on my carby bike, I can't see how it would take any time at all..

    GreyBM very astute comment, i had read up on that and it was actually one of the reasons i decided to buy them as I suspected that due to an aftermarket exhaust the bike was running a bit lean to start with.. so perhaps it is actually back into tune with the iridium plugs?

    Pure conjecture by my part of course..

  5. On my bike I suspect the newer and better plugs took a while to burn out some of the crud inside the head and valves. Bear in mind they were fitted to a motor that was ten years old and with something approaching 100,000 kms on the clock.
  6. Hmm My bike seems to run rich. Wonder how that would go.

    Have tried to do a bit of research and opinion seems divided as to whether these things are better or not.

    Some swear to noticeable improvements in performance and/or economy others say they notice none. One suggestion was that the noticeable increase in power was possibly just due to renewing plugs rather than them being iridium.

    In one of the manufacturer tech sites FAQ's they suggest that extra power wasn't the prime reason for using them. However they suggest that those chasing extra power usually do a lot of tuning tweaks that tend to make normal spark plugs under perform and so this can be offset by iridium plugs.

    I would have thought that any plug which improves combustion as is claimed is likely to give smoother, more usable performance.

    Be interested to hear a few more opinions.
  7. G'day everyone,....

    In the manual for my bike at the Bikeshop it states that only Iridium plugs are recomended. They are installed when manufactured and don't recomend changeing to a differant type.

    I wonder how many bikes have them installed these days when manufactured?

    Dr Who?
  8. I would've thought that if an engine is running right, standard plugs would be fine. EG. my 600 has not had new plugs yet (112,000kms) new ones are still on the table in the garage, I have only cleaned and gapped them about every 25,000.

    That said I'm sure that some of the new bikes will be running a lot leaner than my carbie, no emission 1993 thing.
  9. Good day... Just fitted IRIDIUM plugs to my GSX750F as I have already a few performance parts fitted so hard to say.. I'll keep you posted.. Its done 20000km... I think that its smoother but we ll see
  10. Yeah my GSX-R750 comes with them stock (or so the book says) and "the book" agrees that only iridium should go in as replacements. I bought a set for my 12000km service with all intentions of checking the existing ones (which I expected to be fine) and just keeping them on hand for future services....

    ..Unfortunately the plugs were harder to get at than anticipated - so the old ones are still in (performing just fine, like hawklords... only 100000km younger) and the new ones are on the shelf. :)
  11. My Bird came with them stock, Honda recommend that iridium plugs should only be fitted,
    I have done 52,000 kays on them and they dont need replacing as yet,
    Honda international blackbird site I am on they are getting 75,000 miles to a set,Minimum,

    My Bonnie. I was always replacing plugs, they would break down under load, didnt get far on a set of plugs, And I used the most expensive ones at the time,
  12. Hmm, always been a bit sceptical of Iridium plugs, especially given some of the horror stories involving the tip falling off and destroying the engine.

    Still, I suppose it's quite likely that any problems they may have had should have been sorted out by now. Might try a set in the GPX and see how they go. At least that way I only have to buy two, and anything that saves the hassle of changing the plugs on that bike will be worth the money.
  13. Iridium just last a bit longer. Where the **** do you wood ducks hear this shit?
  14. Ever notice you typically only get a static shock touching something with one finger, and not with your whole hand - that's the same theory behind iridium plugs (smaller electrode means less voltage required for a spark, or bigger spark for a given voltage).

    Whether they work in practice or not I'll be testing as soon as the plugs I ordered recently arrive in the mail. I won't however be doing what most people do and comparing them against a worn-out set of copper electrode plugs, since the plugs in the Kat have so far only been used for tuning the engine.
  15. Iridiums will improve starting - but its not that much a big deal!
    I wouldnt waste the money for them, but if you have the dosh, why not?
  16. it's not just starting, they last a lot longer......

    and as far as I can see, this thread is full of peoples' experience with the plugs, not what people say about them.
  17. Exactly why I'm reserving judgement till I've tried them myself.

    And it's not like the price is that big a deal. Fitting Iridiums myself is still many times cheaper than paying a mechanic to fit standard plugs (and taking their word that they actually did).
  18. I've put a set in each of the bol d' ors, and the difference it made to starting is immediately obvious. These bikes were never a good cold-start proposition, but now they both (the 1100 especially) jump into life with a bit of choke and a quick stab on the starter. I'm not sure of any other benefit or gains in power, my main concern was to cure the cold-start 'feature', and they've certainly done that. Put a set in the kat jd :wink:
  19. I've ordered a set, still waiting for them to arrive in the post :p.
    Good to know they do help with cold-starting as that's certainly my main interest in them. I've already had a couple of mornings below 5 degrees in the last month.