Iridium spark plugs?

[XS1100_OEM4ME]

Opinions Vary

Like Patrick said in Road House "Opinions vary" I am going to leave it to "If it makes you happy, it can't be that bad" (Sheryl Crow) I knew a guy once the swar Slice 50 saved his car motor , if it made him happy, well you get the idea Here are some more "so-called" expert opinions, chose wisely grasshopper

http://mechanics.stackexchange.com/q...-iridium-plugs

[jwhughes3]

At 92,000 miles I just replaced the Iridium plugs in my 2007 Honda Accord. The old ones still looked fine. I am hoping the new ones will bring the mpg back up to what it was at 10,000 miles!

John

[LoHo]

I wonder at the "not worth it" comments. It is thirty or so extra bucks for plugs that spark more consistently and last longer, which we all seem to agree on. Those seem to me to be two real benefits that are hard to deny. The "our bikes weren't designed for them" argument can also be said of the oils, tires, and gas we use, let alone the chain drive/750 rear end/drilled air box/individual pods/etc., that are regularly discussed. I haven't seen a post yet where someone says "My Iridium plugs foul a lot", only posts that claim this happens.

My old Virago started with iridium plugs but not with stock plugs, probably because of ratty connections that cut the voltage to the point where the regular plugs didn't get enough voltage to jump the gap. Yep, I've cleaned the connections, but haven't gone back because the IR plugs work.

I think I'll just invest the money I was saving to buy a chain drive conversion on plugs that work for me.

[crazy steve]

I wonder at the "not worth it" comments. It is thirty or so extra bucks for plugs that spark more consistently and last longer, which we all seem to agree on...

I would say if you're fully confident that your bike is running very well and will continue to do so, they would be worth the extra money. But as we can tell from the number of 'trouble' posts this site gets, that's not always the case.... Have a bit of minor carb or ignition trouble, and you may foul those expensive plugs beyond cleaning, at which point that extra 30 may be a big deal...

Would I buy them? Maybe, maybe not... but whatever you do, I'm ok with...

[clcorbin]

Fouling isn't really a function of the plugs (correct heat range assumed!) so much as it is a function of a properly tuned engine and a mechanically sound engine.

The smaller tip of the iridium plugs does improve it's ability to fire in adverse conditions because it focuses the electrical field tighter. This does mean they will ionize the combustion gases between the gaps at a lower voltage than standard plugs, so they will not need to get to as high a voltage to fire any given mixture than standard plugs. That is all simple physics that has been known since the days of Tesla.

The reason copper plugs don't have narrow tips is simply because they would melt off almost instantly. They simply can't handle the temperatures that iridium plugs can, so they have to make the electrode and ground strap much, much larger to conduce the heat away quickly. Iridium can handle the heat, so they can be made nice and thin, which works better with the physics of ionizing gasses. Unfortunately, iridium is expensive stuff!

I still remember my first modern 2 stroke bike, a 1999 YZ250. That bike came stock with NGK iridium plugs. When I bought it new, I also bought two extra plugs (at $12 a pop) and put in my fanny pack. That was because I was used to older bikes that had less effective ignition systems, less well tuned carbs and old school plugs that would foul in the blink of an eye under certain conditions, so you had to be ready to swap plugs on the side of the trail.

With that YZ, I STILL have one of the plugs new in box sitting in the fanny pack to this day. I DID swap the plugs once, just because I wanted to see what the old plug looked like. I never did have any reason to swap it on the trail.

[clcorbin]

Oh, and I would LOVE to see some actually data on iridium thin electrode plugs fouling faster than old school plugs. Given how hot that thin tip is, it will burn off a LOT more crap a LOT fast than a "cold" copper plug ever could. IT might be a problem with iridium wide electrode plugs as iridium does have higher resistance than copper, so that might play into things. But not the NGK ones.

[Bonz]

Like I said back in post #13 and subsequently in other posts, my BS flag is straight out in the wind on anything related to correct heat range Iridium not being suited for an XS 1100 or other vintage bike when it comes to any negative performance variable, other than cost.

Everything about an Iridium plug says it will be better for old ignition systems and even sub-par tuned engines.