usually you look for about 2 threads of heat to show on the plug, if that color i can see on on the porcelin is actually grey or tan about 3/16 from the electrode its pobably pretty good. BUT thats not saying the whole fuel curve is right, just at wherever you rode it the longest. It could look like that but be fat on the pilot of you were wicked wfo, and it could be lean on the main but right on the needle if you were pussy-footin