Iridium Plugs - Ducks nuts or Utter rubbish

[YZ250H]

Holeshot expressed an opinion that they are rubbish (for a YZ465 anyway).

What's the low down / your opinion ?
I was shocked after paying for one recently at the price - are they that much better than the standard old plug or a marketing gimick ?

[LWC82PE]

they get a big thumbs up from me.  (NGK  & Denso brands)

[Colin Jay]

I have had a 50% success rate with them in a very hot 500 Yamaha engine in my dry lake racer. The first plug failed after about 5 minutes of running, it would spark when test but would not fire in the engine (12.5:1 compression ratio, 102 octane race fuel). The second plug is still ok, but has not done much more than 10 minutes of run time.

CJ

[asasin]

I use them in my 125's ( ie thrash machines).Dont let them oil up ,they really hate it 

[DR]

can't justify the cost and once they foul it's usually bin time as they're fussy little blighters that don't take kindly to being fouled as stated. Can't say I've ever noticed any difference in anything except the price. Have had failure straight out of the box too unlike the ES series where I've never had a spot of bother I use the BR8ES in near everything these days, same deal but with a built in resister to supress electrical interference.

[Lozza]

Have a dyno print ot of a 25hp engine showing a 0.5hp gain across the rev range from running a proper race plug.Show me a bolt on part that can do the same for the same cost

[JohnnyO]

One thing i've found is a B8ES works best with a PVL ignition because most the other plugs seem to have a resistor which PVL say not to use.

[DR]

bottom line Loz if you want to use these plugs you better bring a few spares

[jasmotorbikes]

from what i know of iridium plugs they are supposed two last alot longer than a standard plug my yamaha r1 has iridium plugs in it from the factory alot of sportbikes do and they dont get replaced till the bike is up for its big service at 24,000km thats alot of km,s also there a prick to get at too replace. I also found i had iridiums in a au xr8 falcon maybe it has somthing to do with more modern electronics that thay use these days that the iridium plug is more suited for but it wouldnt hurt to try one in ya 465 i mite try one in my yz490 see if its lasts longer than the $5 plug i run b9es ngk.  

[LWC82PE]

I knew you would be in favour of them Lozza

[mx250]

Gees Lozza the only place you would ever notice a .5hp would be on a dyno .

[LWC82PE]

.5 here .5 there, another .5 there......... it all adds up

[Lozza]

I use DENSO now that last forever Doc not those NGK shitters that come fautly out of the box. Well down Eastren Creeks long straight half a HP is enough to break the tow, enough to repass if you pull a desparate up the inside to turn 2 and enough to pull out of your draft and motor past onto the straight. What a dyno won't show is throttle response, which with a race plug,is off the scale. I've converted enough skeptical tightarse trail bike riders and the phase "I didn't know a plug could make so much difference" is always used.  
But you all keep using those $5 jobbies

[jhovel]

I just replaced the original iridium plugs in my Magna V6 - at 203,000km. They still worked fine but were a bit eroded on the centre electrode.... Can't do that with a standard plug....

[L.Ron.Pursang]

I ran iridiums in my old black Jag because the guy who set up my Motek and MDS ignition told me they were the hot ticket with such a setup. The only difference I noticed was to my bank account, it's an expensive operation replacing 12 of the buggers. I do run them in my PVL equipped bikes as I was told by other PVL users that they were the only thing to use. They seem to work fine but I must admit I haven't tried anything else.