Motorcycle Repair: One cylinder running hot?, honda cbx1000, aftermarket pipes

Question
First of all, I appreciate your time.  I know you said only Honda CBX1000 or CB1100R, but this a general engine question that you will probably be able to help with.  I have a 2005 Yamaha FZ1 (inline-4 w/carbs) with stainless exhaust.  I noticed the exhaust manifold (header?) is starting to discolor (gold/copperish color with a little blue).  What causes this?  Also, one pipe is a darker than the other 3, is that cylinder running a little hotter?  Do the carbs just need synched?  Any info you can provide will be greatly appreciated.  Thanks.  Matt

Answer
Yes the pipe that is discoloring more is running leaner, so a carb sync will definitely help.  If the pipes are stock, then they will normally not discolor too much unless the bike is revved while not moving.  If they are aftermarket pipes, usually they will discolor more easily.  The mixture is the main factor in the temperature of the engine and the headers, but check your spark plugs to ensure the mixture is OK.  Good luck,  Jan