Topic: Read this spark plug
This is an NGK V-Power TR55 with one 14-hour race on it. The rest of the porcelain is bright white with tiny black specks. The v-groove NGK cuts into the copper electrode is still sharp and looks new. I did a little research on reading spark plugs, but nothing I found could explain the big black spot. It's not soft carbon--I tried to clean it off after taking the picture and it's burned onto the plug. Engine seemed to be running fine.