One blue pipe?

What would cause one of the four exhast pipes to turn blue? The carbs are clean, synced, wet set, valves in spec. As far as I can tell, each carb is identical to the others including float height, pilot screw settings, and all jets.

 

you have a cylinder running lean. have you colortuned or done plug chops on it. pilot screws won't always be equal they have to be set for each cylinder.

 

I just pulled the plugs and they all have that beautiful light brown color.
I did colortune, but found that there is a broad range of blue, and decided to set them all the same and see what happens. I've seen different opinions on how to set the pilot screws with the colortune plug. How do you do it to avoid being too rich or too lean?

 

Turn it so the flame goes yellow then back to blue and a little bit and keep the color even across the boards. If one pipe is blueing and the others are not your are almost certainly hot on that pipe.

 

I'd trust the color of the plugs for having the carbs set to the right richness. The color of the pipe is not a proper way to determine this. Could be a problem with the pipe it self.

 

same thing happened to me, inner pipe of #2 header failed, still the only blue pipe 30k later, its only on the top bend

 

Yeah, could just be the inner wall having a hole

 

Exactly. If the inner pipe is cracked, or rusted through, it will allow direct contact with the exhaust gas, which is hot enough to "blue" the outer pipe.

I agree that plug color, the results of your ColorTuning efforts and how the bike runs are much better indicators of your state of tune.

 

Mine is # 3, but like yours, only at the top of the bend. I guess I just ride it rather than worry about it?