Why do pipes turn blue?

I have always wondered why pipes turn blue? I have heard that when they all turn blue the same on each pipe that its running right. I also heard when they turn blue its cause its running rich?? I dunno i hope some one here can help me. Thanks

the blue is from too much heat, it could be carb being lean or timing off a bit, it dosent take much

Chrome blues when heated. The pipes on an inline four tend to be single walled and blue fairly easily. Stainless tend to get gold colored with bluing. One of the reasons most cruiser bikes, that want to be pretty above anything else, will use a double-wall pipe system. The inner pipe will be blue or black from heat and the outer pipe, which has a bit of airspace between it and the inner will remain bright and shiny. DG HardKrome made its name from using this system. Essentially the outer pipe is a heat shield.

High heat turn them blue. Correctly tuned Kawasaki inline 4's (at leat KZ650s) do not turn blue. I say this as the original owner of a 46,000 KZ650 with original pipes that have never turned. The original pipes may be dual wall, I don't know because they have never been off the bike.

Some bikes, like BMW boxers, always turn blue because the sharp bend gets very hot. Others, like new Harleys, turn blue because of excessively lean tuning from the factory. New Harleys have a decorative shield covering the pipes so the blue doesn't show.

oldkaws4ever wrote:

I have always wondered why pipes turn blue?

It's some kind of oxidation reaction when the chrome steel gets hot enough to react with the air.

650ed wrote:

Correctly tuned Kawasaki inline 4's (at leat KZ650s) do not turn blue. I say this as the original owner of a 46,000 KZ650 with original pipes that have never turned.

I think you're right, I just took the original pipes off my '78 650 and was amazed that they had very little blueing. They are very rusty and dented but no blueing I think tuning has a lot to do with it, doesn't run overly hot.

There is a coating for the inside if you don't like blue pipes. Cost you a bit extra but won't blue once treated. For a hundred dollars extra I don't think it is worthwhile. Just my .02

i dont mind the blueing i think it kinda looks cool, it ads charecter to the bike. I

From holding their breath too long!

damn why didnt i think of that?????

I believe the discoloration occurs during either of both extremes.

I prefer blue pipe, to blue balls.

I had an opportunity to work on an SR last summer that had the head pipes cut off before the collectors so a pair of Jardines could be slipped on. Looking at the cut ends the double wall was evident.

My SR's pipes are slightly golden but have not gotten any darker. Proper jetting is the key.