what spark plugs do you use?

[clcorbin]

Way back in 1999, I bought a new 1999 YZ250. I also picked up a pair of "spare" NGK iridium plugs for it. 2-strokes and plug fouling and all that.

13 years later, I STILL have the stock plug in it. It would take me a long while even FIND those two new plugs for my dirt bike! Between electronic ignition and NGK Iridium plugs, that bike just won't foul plugs.

[clcorbin]

The small diameter of the iridium's allows them to run very HOT right at the tip of the plug, which helps prevent any kind of fouling. The small diameter all so helps to allow a spark to form at a lower voltage than a larger tip (one of the stranger aspects of high voltage ionization based discharges). The iridium material itself can EASILY handle the temperatures of our engines. And as other folks have pointed out, there is pretty much nothing you can do to get enough spark energy out of these bikes to actually damage them.

The only downside to the plug is how much easier it is to damage the tip. The small diameter is obvious, but iridium is also pretty brittle, especially if you are used to dealing with fat copper electrodes. Oh, and they cost a bit more.

I just wish NGK would make an extended reach plug for my 2005 Mustang GT...

[James England]

Always NGK iridium plugs. I remove the resistors from the HT caps and put a piece of wire in there instead...... Nice fat sparks

[Bonz]

Iridiums in my 80SG, been flawless.

Question: my project 80G has BP7ES from the previous owner, I've been running them for 1200 miles now simply because they were in the bike and after a proper tune they have turned from the dark side to a nice white-tan. Any compelling reason performance wise to go to the 6ES, as these are doing fine here in the summertime temps. I would assume let the plugs tell me if they are not getting hot enough?

[clcorbin]

Always NGK iridium plugs. I remove the resistors from the HT caps and put a piece of wire in there instead...... Nice fat sparks

I built up a set of wires from 8mm Accel wire and caps. They are not resistor caps. I know, because I crimped the wire to the connector myself...

[MPittma100]

No Problem

According to the literature, the iridium plugs are supposed to conduct electricity more efficiently resulting in a hotter spark. They also don't want you trying to adjust the gap due to the small diameter of the center electrode - evidently it's pretty easy to damage it. I thought about trying them but was affraid the hot coils would do bad things to them. Either of you guys running iridiums have high output coils installed?

Using the Dyna coils and Iridium plugs, solid wire plug wires. Everything works properly, runs fine, good MPG. No complaints. I wish that MSD made something for these bikes. That would be the ticket.

MP

[Bonz]

Iridium is tougher than copper or other center electrode materials, so you would run less chance at wearing it out with a high output ingnition system vs a tyipical copper core plug in my estimation.

The smaller center electrode isn't as stout because it's so fine in size, thus the care in setting gap.

[clcorbin]

Iridium is tougher than copper or other center electrode materials, so you would run less chance at wearing it out with a high output ingnition system vs a tyipical copper core plug in my estimation.

The smaller center electrode isn't as stout because it's so fine in size, thus the care in setting gap.

Iridium my be "tough" in the sense that iridium spark plugs last a very long time, but iridium is not "tough" in the engineering sense. It takes much less energy to break iridium than it does a "tough" metal like copper. Therefore, it is not "tough" from an engineering point of view. It is very brittle and very hard to process. It won't take much side load without snapping (think glass rod and not steal music wire). The very small diameter of the electrode doesn't help in the "tough" sense, but it does help keep costs down AND it improves the spark.

One huge advantage (and the main reason it is used) is that it maintains decent mechanical strength at temperatures that would have copper sitting in a glowing yellow pool. That is another reason it can get away with a small diameter.