Trying to dial in an 07 YZ450 riding around 7500FT and only change I have made is to change to a 158 main jet. The header pipe near the cylinder head is blue for about 6 inches and looks like it is quite hot when riding. My plug color is very light around the center and black around the outer edge. I have a little poping on decel but not much. Just don't want to run too lean. Anyone else notice the color of thier pipe being blue? Can't spell and can't type, you get the idea.