Spark plugs

[Ignacio]

Hold a spark plug up and look at it closely, squint and grunt as you look as hard as you can -- the plug still looks almost new. Take that plug to a microscope and look at the used plug's electrodes vs a new plug and you can see that the used plug's electrodes are indeed quite rounded causing poor arc ignition.

Oh, that is so good! :clapping:

Next time somebody says in this never-ending subject, "I pulled the plugs and they look fine." I'll ask what power objective they used on their microscope to determine that.

Thanks for your expertise ionbeam.

 

[Fred W]

The very least you should do is to swap the positive and negative iridium plugs' locations, probably at the same 16k mi interval that you would be changing the (1/2 price) non iridium plugs at. Remember, that side electrode is wearing at the same rate as the non iridium plugs' side electrode.

 

[BkrK12]

Oh geeze.
I thought you were going to agree that I'm, a cheap prick... :blink:

I have no idea if you're cheap.

 

[HaulinAshe]

CR8EIX can be purchased at Advance Auto stores for $6.99 each. You'll have to order them, and it takes about two days to arrive. Ask for Item #4218.

I'm +1 to Geezer. New plugs every year, regardless of mileage. I do it more for the assurance that the threads are not corroding than the condition of the electrodes.

 

[ionbeam]

...I do it more for the assurance that the threads are not corroding than the condition of the electrodes.

Again Jeff brings up a real good point. Not only corrosion between the plugs and the cylinder head but carbon buildup on the threads on the plug tips too. If any of the plug threads are exposed inside the cylinder hard carbon can build up and then destroy the cylinder head threads as the plug is unscrewed.

 

[v65]

New plugs every year, regardless of mileage.

And when was the last time you had a year that two plug changes weren't mandated by mileage?

 

[charismaticmegafauna]

• Carbon is a partial conductor leading to high voltage leakage paths that bleed away some of the high voltage that should be contributing to spark intensity.
• As the plugs age the sharp edges of the center electrode and ground electrode erode. When a plug is new, the ignition spark will seek out the most favorable area from which to arc. Over time this area erodes and the spark moves around to the next best arc location. ...you can see that the used plug's electrodes are indeed quite rounded causing poor arc ignition.
• ...real test. ...stone cold FJR, turn the key on and hit the starter. ...battery voltage sags as the starter spins, lowering the coil's secondary voltage. ...plugs can get wet and then you have a no-start.
• Now the starter is hot, the battery is discharged and you are pissed...
• ... for 9,000 rpm and maximum performance. ...coil has to try to recharge to full energy ~75 times each second. ...cripple this with carbon leakage and unfavorable arcing at the electrodes.

Yep, all the little electrons build-up on the flat surfaces ('cause they can't find a place to 'leak across') and when the 'tension' gets big enough -- "whammo" big/hot spark.

Added info: rare/exotic metal (silver/gold/palladium/iridium/?/etc.) fine-wire-elctrode spark-plugs (reportedly) need much less voltage to "fire".

If you have your plugs out just replace them and don't reuse them.

B..b..but..., wha'do I do with the old ones? -- put 'em in a drawer or sumpin'...?

why not change them if they are at or over recommended change intervals for standard or iridium plugs.

I don't know if there is a recco'd 'change interval' for iridium plugs (since they're not OEM for FJR)?

Some say they're "life-time"...

 

[ionbeam]

I don't know if there is a recco'd 'change interval' for iridium plugs (since they're not OEM for FJR)? Some say they're "life-time"...

DENSO say:

DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.

 

[Grumpy]

I don't know if there is a recco'd 'change interval' for iridium plugs (since they're not OEM for FJR)? Some say they're "life-time"...

DENSO say:

DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.

Of course,.............. if I was the marketing guy for Denso, I'd say 20k or lower.

 

[HaulinAshe]

And when was the last time you had a year that two plug changes weren't mandated by mileage?

Lemme think...