1999 kx500 stock carb, 1500ft elevation, 58 pilot, 168 main, air screw half out. Bpr8es ngk plug. 93 octane pump gas bel ray h1r synthetic oil mixed 40:1. Vforce 3 seeds uni filter fmf gnarly header fmf powercore silencer. 86 flywheel and stator. Stock bore wiseco window piston. ...... I just put in my new window piston and top end kit. Been doin the break in procedures yesterday and today. I checked the plug after every run once cooled. Always tannish brown as always was before rebuild. But today the tip was grey after a run. Although today was 47 degrees which i should have probably had a 170 main in according to the chart on here but lean is white grey is hot right?? Thanks