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The stock NGK is a good plug.

I have found a bit smoother idle and low end throttle response with the Denso Iridium plugs is several aplications, including my S3.

The Denso Iridium IU27 or IU27a, has a very fine wire tip that is very hard to foul, is very easy for the spark to jump, and lasts a long time. The cheaper NGK iridium has a but larger tip and a different internal construction.

Side note - If you buy several sets of plugs at the same time, put a volt/ohm meter across them and group them by resistance. The ignition likes to see the same resistance across all plugs, and they can vary quite a bit from plug to plug.not a big deal, but the little things add up. ;)

See more on ignition and plugs here:
http://www.thespeedtriple.com/Forums/index.php?topic=376.0

Others may have different experiences and/or recommendations.
 

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Just for reference:


Stock NGK CR9EK (iron tip):




NGK iridium CR9EIX:




Denso iridium IU27a (rounded, U-groove electrode):




Denso iridium IU27 (pointed electrode):
 

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Doh, you're right. So the CR9EIX will fit just the same as the CR9EK? RPM gave me the totally wrong spark plugs so I'm going to return them for a spare set that'll fit. I think my 03 uses the CR9EK as shown in your pics.
 

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kuhlka said:
Doh, you're right.  So the CR9EIX will fit just the same as the CR9EK?  RPM gave me the totally wrong spark plugs so I'm going to return them for a spare set that'll fit.  I think my 03 uses the CR9EK as shown in your pics.
The EIX suffix is the iridium tip on any NGK plug.
CR9EIX breaks down to (C) 10mm, (R) 3/4 inch reach, (9) heat range, (EIX) platinum core, iridium tip.
CR9EK breaks down to 10mm, 3/4 inch reach, 9 heat range, platinum core, iron tip.

If you can't find plugs locally, you can always try www.sparkplugs.com
This is the site for Monarch Products - the US distributor for many plugs (and other parts) - just not Bosch. The more you buy, the lower the price.
 

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I went with the NGK iridium CR9EIX from http://www.sparkplugs.com/. I had terrible results years ago on a totally different application with ND plugs back when the U channel was their hot new gimmick. They may be great in speedy but I have been using NGK with good results for 20 years & don't see any reason to change since the stock plug is also NGK.

As a general rule, any new plug will give a small power increase over an old carboned-up plug. Every once in a while I have found an engine that hated a particular style of plug but I have never found a magic plug that performed way better than anything else.

Now my first Rickman Metisse with a Joe Lucas magneto ignition, that was as picky a plug fouler as I have ever seen.
 

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dr_gallup said:
Every once in a while I have found an engine that hated a particular style of plug but I have never found a magic plug that performed way better than anything else.
I have, but it is not available in a 10mm thread - only 14mm. Bosch makes a modified surface gap racing plug that has made more power in every engine I have tested them in, from 540ci Chevies, to two-stroke engines. They are commonly used in F1, NASCAR, and several other forms of racing - all with very good results. You ought to see the way it acts in a pressure chamber, and the burn patern results on the top of pistons - very impressive spark kernal that initiates a much larger burn pattern.

On your old Rickman, did you ever try the Champion "power gap" plugs? Magnetos seem to love them, too bad they are no longer available.
--------------------------------------------------------

Bosch F09DER modified surface gap.
Notice hand cut threads and side/surface gap electrodes.
Don't bother trying to ask the local plug supplier about them, "they don't exist" is the normal reply.



 

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Devious2xs said:
On your old Rickman, did you ever try the Champion "power gap" plugs? Magnetos seem to love them, too bad they are no longer available.
I did use a Champion plug that had a unique side electrode. They were hard to come by but worked better than anything else at resisting fouling. The side electrode was a pin that was pressed in a hole drilled in the outer shell.
 

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J-Pip said:
Devi's got all the tricks
And stupid me is spilling too many of them here. :violent1:

By the way, I gave Kartstar a few of the above plugs to test in his kart - after he gets the carb problems worked out.
 

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Devious said:
Denso iridium IU27a (rounded, U-groove electrode):


Denso iridium IU27 (pointed electrode):

Has anyone given the IU01-27 racing plugs a try (one on the right in the pic)?


The ground electrode + center electrode design looks interesting. I mean the way the whole business end hides inside the threaded body.

"Ultra fine iridium center electrode, platinum ground electrode, nickel plated body for extra corrosion resistance". The corrosion resistance at least would be a good extra, even with the new style rubber seals.
 

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Martin_R said:
Has anyone given the IU01-27 racing plugs a try (one on the right in the pic)?
To answer my own question, if someone else is considering these fancy $$$ plugs:
do not bother.

Bike runs a bit rough with these. I'd imagine this having something to do with the electrode, which is quite a bit further away from the piston than with the OEM fitment dual electorde NGKs.

+the nickel plated plug do not rust, but the crush washers still get as furry as with the vanilla $1 plugs.

Quite a bummer, as I thought these plugs would last much longer than stock iron electrode ones.
:mad:
 

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I installed NGK CR9EK's today. the previous plugs were Denso's, can't remember the code, but they look same as NGK's(two side electrodes).

I measured all plugs with resistance meter. NGK's where ~4.5-5 Kilo-ohms, but Denso's where 6-6.5kilo-ohms. Looks like the resistor has a bigger value in the denso's. Less resistanse, bigger spark.

JakeT.
 

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I've been using those iridium NGK ones but can't tell the difference. Smaller electrode = more spark ?
 

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I used a set of Brisk plugs for something different. I think there is a difference but to be honest I've only ridden the bike once in the past 2 months due to work/waiting on silicon hoses etc so I will give it a good run shortly and report back.
 

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Not NotRazorback said:
I've been using those iridium NGK ones but can't tell the difference. Smaller electrode = more spark ?
Not more spark, but better spark exposure, therefore better (faster, more complete) combustion. I put in the CR9EIX's, and have been happy all the way round, but I wondered briefly if the larger EK electrode might not be a performance wash -in our 125 racing karts, guys'll actually look for plugs that take up more space in the chamber, thereby raising CR just a hair more! In the end, the EIX should last longer. The ones I took out didn't really need replacing after only 6k miles.

Devi's fancy Bosch plug makes my CR250 start on the first kick every time!
 

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I was never sure about it, thanks.
But, it makes me wonder. My RX-7's all had plugs like this:

Which I always attributed to 4 points of 'hotter' spark.
 
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