The shee runs great and im confused...........GPS Last weekend, 92.1 mph and pulled sand tires all weekend, pulled plugs two totally different readings, the flat surface closest to piston one chocolate color and one nothing(silver)....I have polished ports, shearer pipes, stock carbs with 27.5 pilots and 300 mains, + 4 timing, .20 over, carbs are totally synched with carb sync tool...ANY IDEAS WHY?