spark plug color

[Robert Haller]

I checked plugs yesterday after a ride and most were light gray with a reddish-brown spot on the insulator. What does that indicate?

[MartyA]

Hi Bob!!

Don't touch anything.

Light gray is good. IF you are filling up at the same gas station most of the time you can get that bit of color in the middle. It depends upon the brand. I've seen tan to yellowish to light reddish orange.

[MartyA]

Unless you have been swimming down there in the warm weather, and got a little water on the eletrode...

What I mean is the plugs could be old, and have started to oxidize.