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I was just wondering how you read the labels on spark plugs. (IE: heat, so on and so forth)

When I just replaced the plugs in my 1000, I took out NGK DR8ES. I know these weren't the right plugs for the bike. But what made them wrong?

By the way, the were covered in black soot, caked with it. Those were old plugs, the metal was oxidized as well.

For NGK plugs...



Every manufacturer has a chart telling what their codes mean.

I've added the ngk image to our download server in parts and informational under folder NGK

good post

Hi All,
Good post requarding NGK abbreviations,
the "one" that always got me, is the heat rating.
Please correct me, if I'm wrong, but, I think it goes like this..
The cooler your engine runs, the hotter running s/plug you need,
and conversely,
the hotter your engine runs, the cooler running S/ plug you need.
2 being hot running S/plug (cool engine),
12 being a cool running S/plug (hot engine)
This means a plug that runs nicely on a road bike will overheat in a
race bike, so you need to have a cooler (running) plug in a race bike.
(heat rating moves towards 12)
And a plug that runs nicely in a race bike, will be too cold in a road bike,
and foul up, causing a misfire, so a hotter running plug would be needed
in a road bike.
(heat rating moves towards 2)
In short, it's the heat path in the plug, whether the plug itself needs
more or less heat to work as intended.
Clear as mud......
Yours Slip.

Here is a good description of the function of a plug.

http://www.ngksparkplugs.com/techinfo/s ... country=US