John,
I know a little bit about this, I've gone through a lot of motorcycle spark
plugs over the years. The R does mean resistor plugs, in Champions and
NGK's as well. In the Champion naming system, the Y means extended reach
plug (sticks further into the combustion chamber), I believe ES means
extended reach in NGK. The number is the heat range, larger numbers are
hotter. I think NGK is opposite, in this respect.
I'm not sure about the "N" versus "C", I've never used plugs with a "C"
there. Maybe this indicates that it has different sized threads than the
"N" series, which is what I run in my bikes.
The "C" at the end means copper core. Champion added that when they went
from iron to copper cores. I'm not sure about the "61" versus the single
digit numbers, that's different from what I'm used to as well.
Unfortunately, all the spark plug makers seem to be going away from this
type of system and to a simple stock number system, that doesn't tell you
anything as far as the heat range, etc.
-Eric
----- Original Message -----
From "Deikis, John" <John.Deikis at med.va.gov>
To: <spridgets@autox.team.net>
Sent: Friday, August 22, 2003 11:50 AM
Subject: spark plugs
> Oh, Great Repository of Automotive Minutia:
>
> Share you wisdom, please, concerning the following:
>
> Does anyone know the system for deciphering Champion spark plug codes?
>
> 'Frinstance, what is the difference between a "RN9YC" and a "RC9YC" plug?
>
> And why do my "C61YC" plugs have no "R"? Resistor?
>
> And what does the number represent? "9" and "61" are not even in the same
> neighborhood. (I realize these are not for the same application, I'm just
> gettin curiouser).
>
> JohnD
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