The pipe of my rear cylinder (TC 88 carbed, pipes are SE 2, newly installed AN big sucker) starts getting a kinda golden colour. Didn't notice that before, so I guess that's a brand new issue. Usually it means, the bike runs too lean (didn't rejet yet). But just the rear one? Isn't that a little odd? Any advice on how to get rid of that coloration?
Golden means too rich, blue is lean. On my EVO, the rear runs a little richer than the front and I do not have any intake leaks. You should check for leaks, adjust the idle mixture and rejet if necessary. How does it run, what do the plugs look like, any black smoke?
Nope, no black smoke. Plugs were black before the AC swap. Didn't take them out since. I always thought she runs too rich, a gas mileage of 30 MPG is a pretty good indicator, isn't it? But she runs smooth, no backfiring (neither in the pipes nor in the A/C). I think we can rule out the leaks, the gasket is brand new, and I don't see yet where it is supposed to leak. I may check out the new MPG tomorrow.
Did you check for leaks where the manifold meets the cylinders, mine was leaking there and still ran fine, runs much better (leaner) after I fixed it and rejetted.
Other than that, sounds like you answered your own question about the rich condition...good luck.
Do you have pipe shields? There is some stuff out there to help remove the blueing but I can't remember the name. They sell it at the dealer though. I think you'll be hard pressed to find bare exhaust pipes that don't blue to some extent.
All single wall chrome pipes will discolor over time, either get some heat shields to 'mask' the colored pipe, get some double walled style pipes, or get the discolored pipes ceramic coated.
All single wall chrome pipes will discolor over time, either get some heat shields to 'mask' the colored pipe, get some double walled style pipes, or get the discolored pipes ceramic coated.