2 Headers bluing but they don't appear to be hotter than the others

[HobzGoblin]

I just had a new Vance and Hines 4-into-1 exhaust installed on my 77 gs750. After less than 150 miles, the two outer headers have begun to discolor. I've been told that this is from those cylinders running too lean and overheating . . . except they do not appear to be any hotter than the middle two, which have not discolored. I checked the temps several times with an infrared thermometer and the outer two were consistently COOLER than the inner two. (I know that infrared thermometers are less accurate on metal surfaces, but it should be able to consistently gauge if one surface is hotter than the other.)

Is there any other reason that headers could discolor other than overheating? And can the bluing be removed without damaging the chrome finish?

2015-08-02 18.59.23.jpg

[posplayr]

Well it is kind of unusual, and I would assume they are in fact hotter despite the measurements. You did not happen to put smaller jets in the outside did you?

[HobzGoblin]

The jets are all stock. (Assuming the previous owner didn't swap them out and I just didn't notice.)

[posplayr]

The jets are all stock. (Assuming the previous owner didn't swap them out and I just didn't notice.)

famous last words

[tkent02]

Could also be a float level thing, but if you are the one who put the pipe on you are the one who should get the jetting right.

The PO had nothing to do with it.

[Guest]

Put a one size up main jet in the two and three.

[posplayr]

Put a one size up main jet in the two and three.

That is what I'm figuring is already there which is why they did not over heat when he swapped out the pipe. He should increase the outsides; they are the ones that look hot.

[dorkburger]

Infared thermometers work good on metal....but NOT shiny metal. When measuring temps on HVAC machines I work on, shiny copper pipe gets a pass of electrical tape over it to accurately read temps. Not feasible on exhaust pipes though.

[tkent02]

I wonder if that aluminum tape would work?

But really that's all fluff, the pipe is hot so richen it up.

[850GT_Rider]

Here's a thought - PLUG CHOPS. Kwitchurgessin'.....

[HobzGoblin]

Could also be a float level thing, but if you are the one who put the pipe on you are the one who should get the jetting right.

The PO had nothing to do with it.

I wasn't trying to blame the PO for my problems . . . just pointing out that I hadn't change jets (and I doubt the factory did either).

And, no, I wasn't the one who put the pipes on. I'm a newb and was doing more harm than good working on it in my own garage so I had someone else put her back together. This thread has given me an idea of what to ask him about when I talk to him later today.

[posplayr]

I wasn't trying to blame the PO for my problems . . . just pointing out that I hadn't change jets (and I doubt the factory did either).

And, no, I wasn't the one who put the pipes on. I'm a newb and was doing more harm than good working on it in my own garage so I had someone else put her back together. This thread has given me an idea of what to ask him about when I talk to him later today.

we will be waiting with baited breath