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Purchased the above noted plugs for my 95" 916. Just curious if there should be any difference in the plug gap.
 

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From LT Synder's maintenance guide, he recommends that the gap on the iridium or platinum plugs have a minimum gap of .030", not the.024" recommended on the NGK site.
 

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so if somebody is going to Run NGK iridium IX's CR9EIX on their 998 how do you get them to .03 as gap spreading is no advisable?
 

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I put mine in ungapped and the bike runs like a scalded dog. I ride an ST3, ymmv.
 

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For me Gapping plugs has been a very important issue for me.
i never trust what the plug gap is from the factory. Champion was notorious for gap specs being off. NGK has been pretty good. Bosch has always been right on.
if the gap is set too hot it can, in some cases, put a hole in your piston.
Better safe then sorry so better Gap em then to scrap em. At the least check the gap and see what it is before putting them in.
 

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ma2ra said:
if the gap is set too hot it can, in some cases, put a hole in your piston.
Better safe then sorry so better Gap em then to scrap em.
I'm interested to hear how plug gap can put a hole in the piston! :)
 

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if the gap is set too hot it can, in some cases, put a hole in your piston.



Yea... Me too... Maybe if the plug is way too long...
 

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The fine-wire iridium center electrode allows the coils to fire easier (at a lower voltage) so you need a larger gap to force the coils to build-up to full voltage. That's the advantage of fine wire center electrodes - they'll fire reliably at a larger gap. Oh, and they last a lot longer and sell for a higher price.

The ND plugs I use come gapped at 0.035 inch and I open that up to 0.045 inch. You shouldn't touch the iridium center electrode because being so small in diameter it bends easily and can crack, so use a gapper which grips the side electrode and just bend it up a bit.

You don't need to go all the way to 0.045 inch but you do need a larger gap than the stock Ducati 0.024 inch or you'll end up with a smaller, weaker, earlier spark, at least that's the way I understand it. Many people just install the iridium plugs and report their bike runs fine.

Don't know anything about "hot" gaps and burned pistons. Hot plugs run hotter but they won't burn a hole in a piston.
 

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Seen it on a sportster many moons ago. The wrong gap run for a long period of time . Higher the compression the better a chance for it to happen. Seen it and happened to a friend on a cross country trip. Smokes like a SOB when it happens too, I was riding behind em. Saw the piston when they pulled it.
Beside why would you "not" check to be sure on your precious high dollar machine? What does it take, 15 seconds to check?
Hope y'all are greasing or anti seizing the threads and using a torque wrench too.
Never hurts to follow procedure. Makes for a good and safe running bike and keeps in hone a good mechanics craft.
JC
 

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ma2ra, you're right - the gap should be checked/adjusted. The correct gap helps to reduce misfires.

But the gap itself will not hurt or overheat the engine, or burn a piston. The gap has not affect on combustion chamber burn temps. The worst that can happen is one gets a misfire event, because the spark was too narrow to initiate a combustion burn (gap too small), or the spark would not jump the gap and start the burn (gap too wide).
 

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ma2ra said:
if the gap is set too hot it can, in some cases, put a hole in your piston.
Happened to your buddy because it wasn't tuned correctly, and ran lean leading to detonation.

Detonation puts holes in pistons, not spark gap.

The only thing too large of a spark gap will do is misfire, because the spark isn't fully igniting the fuel/air mix, because it's too far apart. In boosted motors, we call this blowing out the fire. Higher compression pistons will squeeze the fuel/air mix more, sometimes requiring a smaller gapped plug to prevent blowing out the spark.

I'm not coming from some BS car crap either, I'm talking from experience dealing with motors making 750+whp from 2000cc's and 30+ psi blowing through them. Rule I've always used, run the largest gap you can without misfire. Never holed a piston that way.
 

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This sportster was not in the best way for that long trip. He kept messin with the mixture and timing thru the whole trip. :confused: When we hit wyoming after Sturgis it started to go bad. i figured it was the crappy gas in Wyo but The engine rebuilder in Utah said the plugs had something to do with it. I figured it was a combination of messing with the settings and such.
Nevertheless
what I said about gapping the plug etc etc is important.
jc
 
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