So I am trying to get the jetting dialed in on my bike (YZ450F) and am trying to understand the spark plug colors. I know the lighter the plug the leaner it is a vice versa but what part of the plug should I be looking at. On mine the tip of the plug (where the spark hits) is pretty light, but where the actual threads are on the spark plug it is really dark and a little wet. So my question is what part of the spark plug should I be looking at? I seems weird to me that where the spark actually hits the metal is really light but all around the threads is really dark (pretty much black) and is a little wet.