IRIDIUM Plugs Info

[Stig / Major Tom]

 NGK Iridium spark plug info

Torque specs: Aluminum head 7.2 > 8.7 lb. ft.
Or 1/4 > 1/2 turn after crush washer makes contact
Use new crush washer ea. time plug is installed

.

    Fine Wire Center Electrode Ensures High Durability and a Consistently Stable Spark
    Iridium Alloy has an Extremely High Melting Point
    Trivalent Metal Plating Provides Superior Anti-Corrosion and Anti-Seizing Properties
    Corrugated Ribs Prevent Flashover
    Pure Alumina Silicate Ceramic Insulator, Provides Superior Strength and Better Heat Transfer
    Copper Core Aids in Heat Removal
    Triple Seals Prevent Leakage
     Enhanced Ignitability

Longevity : 40,000-50,000 miles in a scooter/motorcycle

"Some manufacturers numbering systems are opposite the other - for Champion, Autolite and Bosch, the higher the number, the hotter the plug. For NGK, Denso and Pulstar, the higher the number, the colder the plug."

Stig

[Chris0381]

Its obvious under tightening can cause compression leakage but many would not think over tightening can cause leakage also. I'll have to look into where to get compression washers for the times I want to inspect my plug. I'll be changing my plug today actually as the old one seemed quite fouled on inspection.

http://www.ngk.com.au/spark-plugs/technical-information/spark-plug-analysis

9 : Under or over tightening

When the plug has not been tightened enough, the combustion gas leaks out the thread portion. This reduces the radiation of the plug, causing the metal shell to be heated, resulting in discolouration of the metal shell plating. If the metal shell continues to overheat the plug temperature may rise and abnormal combustion may result.


When the plug has been tightened too much the thread neck portion of the metal shell will be lengthened. When the threaded neck portion is lengthened, the insulator and metal will not seal tight enough, causing the combustion gas to leak. When the gas continues to leak, the plug will be overheated and abnormal combustion may result.

[CROSSBOLT]

Good stuff, Stig! Put an iridium in the DT300i and the Like a couple of years ago, sold the Like and the DT is still with it. Her People GTi300 still has OEM plug. Chris, ya might over-tighten with a cast iron head but probably not an aluminum. The threads in aluminum would probably strip before the plug shell stretched!

Karl

[KymcoRockr]

Try the Nippon Denso Iridium plug. Nippon Denso invented the Iridium plug, and they are usually cheaper than NGK, the electrode is a smaller diameter, which is better, and the quality is about as good as it gets in a spark plug. Rockauto.com always has great prices on them.

[Stig / Major Tom]

Try the Nippon Denso Iridium plug. Nippon Denso invented the Iridium plug, and they are usually cheaper than NGK, the electrode is a smaller diameter, which is better, and the quality is about as good as it gets in a spark plug. Rockauto.com always has great prices on them.

I didn't like the color of the Denso after 100 miles. Went back to NGK.
But carry both under the seat.
I give the NGK 1/4 turn after firm contact.....felt about right yesterday morning.  I don't know if I'd trust even a $200 wrench with that tiny little fine threaded plug!
Glad I don't have to go in there again for a while.

It is smaller wire...noticed that.
Good plugs both.
Stig

[Mr. Paul]

Thanks for the info Stig! After my Helicoil repair of my plug threads, I put an Iridium plug back in. I NEVER want to have to replace it. BTW it runs great.