NGK Iridium Spark Plugs

[BigJimmyW13]

That's exactly what I did. I figured what the hell I'm in here anyway. And it dawned on me to ask that time. So I did...

 

[angus67]

thaks jimmy. Now about that a/c~d/c headlite.....

 

[yamaman]

The open side needs to be facing the combustion chamber.

First you said it had to be facing the piston, now you say face the combustion chamber.

Where excactly is the combustion chamber?

 

[tx650]

First you said it had to be facing the piston, now you say face the combustion chamber.

Where excactly is the combustion chamber?

Yeah your right I meant the combustion chamber which is the dome space in the head.

 

[yamaman]

4. Indexing

This is for racers only !!
Indexing refers to a process whereby auxiliary washers of varying thickness are placed under the spark plug's shoulder so that when the spark plug is tightened, the gap will point in the desired direction.

However, without running an engine on a dyno, it is impossible to gauge which type of indexing works best in your engine. While most engines like the spark plug's gap open to the intake valve, there are still other combinations that make more power with the gap pointed toward the exhaust valve.

In any case, engines with indexed spark plugs will typically make only a few more horsepower, typically less than 1% of total engine output. For a 500hp engine, you'd be lucky to get 5hp. While there are exceptions, the bottom line is that without a dyno, gauging success will be difficult.

From HERE

 

[TeeCat]

Pete -

Got a set of Iridiums for my '73 as recommended on your chart. With your PAMCO and dual point coil (not the Green Monster), can I run the gap as it's set? I think it's likely 28... have not measured ithem yet.

Thanks... might lean it out just a touch too... will keep you posted as soon as I can get out for an hour or so.

TC

 

[Sundie]

I'm currently running a brand new set and only checked the gap - 28ish.

 

[yamaman]

These new exotic plugs have very thin centre electrodes. Most makers suggest not altering the gap due to the danger of snapping them off. This is mainly to cover their arses I'd think. But something to think about as your jamming a screwdriver into the gap!

SOURCE

 

[pamcopete]

Pete -

Got a set of Iridiums for my '73 as recommended on your chart. With your PAMCO and dual point coil (not the Green Monster), can I run the gap as it's set? I think it's likely 28... have not measured ithem yet.

Thanks... might lean it out just a touch too... will keep you posted as soon as I can get out for an hour or so.

TC

Sure, that will be fine. You can always set the gaps narrower, even if you have a flame thrower coil, you just wont get the full benefit of the higher output voltage.

 

[TeeCat]

Okay guys... thank you very much!

 

[TeeCat]

Well, I installed the Iridiums today and took the bike out for about 45 minutes or so. I think she likes them. My decel crackle seems to be more of a rumble, and the idle does seem to be smoother.

I have not read them yet, but I will. The old left plug looked close, and the right one looked a tad rich. I tweaked the right pilot screw about 1/8 turn in, so we'll see how things go.

I don't really think I have a chronic idle issue any more. Maybe replacing the manifolds helped with that... not sure. But the rpms come right back down in a snap, and the idle seems to be fairly stable, if a bit low now, even at 55F and sunny. I'd like to bump it up a few rpm.

But today was a good day. She starts from cold on the first wet kick, and fires right up at the gas pumps on the first kick. Oil leak seems to be mitigated by the Mike's reed valve I installed last season. We're getting there.

TC

 

[yamaman]

HERE'S a good discussion from 650rider on this subject.

 

[Dillrepair]

so is there a definitive answer on gapping these iridiums... i was going to try it later becasue i realized i'd never set the gaps when installing them (bike runs fine btw) now i'm reading this and maybe i shouldn't.

 

[OOMER]

I put two in my 82 Heritage Special the other day and it definitely ran better and started better. I did not alter the gap, just put them in as they were.

 

[volcom8877]

Can you run those plugs off a stock coil?

Posted via Mobile

 

[OOMER]

Sure you can.

 

[bcthomas]

I just put some in my xr1200 last week. Seems to have better throttle response and it lost the occasional cough.

 

[Dillrepair]

yeah i've been happy with them. its been long enough since i installed them now that i can't speak for any performance gain because i installed them along with a carb rebuild and re-jet and changed to pods and exhaust all at once so there were a lot of contributing factors to my power gain. The dyno numbers i've seen in several places on the web verify the iridiums though. maybe someone has a link to those.

 

[Tomterrific]

Don't try to gap the iridium plugs. NGK sells different gaps. The -XX number refers to mm, so a -11 gap is .044".

Tom Graham

 

[Blainethemono]

- ngk info blurb

- more iridium stuff

NGK Iridium Spark Plugs Feature
More Durability and a Higher Melting Point Than Platinum
Better Center Electrode Anti-Oxidation and Anti-Erosion
Improved Ignition
Superior Anti-Fouling
Lower Required Voltage
New Metal Shell Plating Process for Better Anti-Corrosion

- the tip and electrode are very brittle as you will find out if trying to regap them

32,000 miles out of a set of NGK Iridiums on my ZX11. NEVER gapped them once. That is what the IRIDIUM is for...... very hard, the tip lasts longer.....and since its a tinier point of spark, more complete combustion, hence a teeny bit more mileage and hp...