Topic: Header Pipe Discoloration - Golding

[EverettShadowbrook]

Hi all,

76 750K

I have seemed to get my bike pretty dialed and have been commuting on it 70-75 miles roundtrip about 3 times per week for the past two months. Since then I have noticed my stock 4-4 exhaust has started to turn a golden color. The discoloration begins at the exhaust port and continues about 12-16 inches down the headers. The discoloring is equal on all pipes. I pulled the plugs and they appear to be in spec with what I have found at dansmc.com. One plug has some carbon buildup and if I had to choose I would say overall the bike is running a bit rich (based on gassy smell at startup). The bike has good/consistent rev through the range with no popping while riding and idles smooth after little warm up.

My question... is this something I should be concerned with? Just want to be sure I'm not running too hot and cooking the engine with each ride. Hoping the attached photo will show what I'm talking about (its not terrible). Most bikes I see on here with stock exhausts don't appear to have this problem


Thanks in advance

[GammaFlat]

Have you tried a "plug chop"? 

[Gordon]

Have you tried a "plug chop"? 

+1

If you do a plug chop at the speed and throttle position where the bike spends most of its time (sounds like highway in your case) you'll have a better idea of what the mixture is like.

[EverettShadowbrook]

Great thanks guys looks like a plug chop is in my future. Off to the search function to research the steps.

Is this discoloration normal for the stock pipes, or is it a definite indication that the mixture is off?

[Jerry Rxman Griffin aka MuthaF'er]

Stock pipes are double walled to prevent this. Discoloration is usually caused by higher than normal temperatures usually due to a lean burn condition. You may need to increase your jetting as you may actually be running somewhat lean and need more gas to cool it down.

[traveler]

golding=lean
bluing=rich

[GammaFlat]

golding=lean
bluing=rich

I did not know this.  I have anecdotal evidence to support the bluing.  I was rich and had bluing going on

[Gordon]

golding=lean
bluing=rich

I did not know this.  I have anecdotal evidence to support the bluing.  I was rich and had bluing going on

Both yellowing and bluing of the headers is caused by higher than normal exhaust temps.  The color they turn depends on the type of exhaust, double-walled or single-walled, the temperature inside the header, and the quality and thickness of the chrome and sub-plating.  That is not a foolproof or very accurate formula for determining the condition of your fuel/air mixture. 

[traveler]

I respectfully disagree.

Just do plug chops, and seat of the pants.

~Joe

[Gordon]

I respectfully disagree.

That's cool.  Could you explain why? 

[EverettShadowbrook]

Can both rich and lean conditions cause the discoloring to occur? Waiting for my bike to cool down and I will post a pic of the plugs for opinions.

[333]

I respectfully disagree.

That's cool.  Could you explain why? 

Cause he was brought up to be respectful?

[jro75]

now I am curious...my 550 had some blueing on the headers and I just assumed it was because of the lean-running condition I received it in (the PO ran pod filters and stock jetting).

[traveler]

My experience with Harley's and drag pipes, when using an Air/Fuel meter, was that lean engines will "yellow" a pipe with a quickness.  Have also seen bikes that were rich that turned the pipes a dark blue almost purple color.

If one really wants to know, all you need to do is get access to an Fuel to Air meter and check it out though.

[EverettShadowbrook]

Here are the plugs. #1 looks very rich. What's your opinion on the other 3? Too lean?

[Gordon]

My experience with Harley's and drag pipes, when using an Air/Fuel meter, was that lean engines will "yellow" a pipe with a quickness.  Have also seen bikes that were rich that turned the pipes a dark blue almost purple color.

If one really wants to know, all you need to do is get access to an Fuel to Air meter and check it out though.

I've seen the same thing you describe.  However, I've also seen an engine running so lean that it caused the headers to begin glowing, after which they turned blue.  

The reason I say it's not an accurate way to diagnose a rich or lean mixture is because of the fact that both types of discoloration are caused by excessively high header temperatures.  The temperature the header gets to is determined by the degree to which the mixture is lean or rich.  Both overly lean and overly rich mixtures can cause the headers to overheat in a wide range of temperatures, causing either yellowing or bluing of the chrome.  And the temperature that the outside of the header reaches is significantly affected by the composition/thickness of the chrome and sub-layers, as well as whether the pipes are double or single walled.  

I have to agree, though, that using an exhaust gas analyzer is definitely the best way to determine the mixture, and a plug chop is probably the next best way.  

[Gordon]

#1 is definitely rich.  2,3 &4 look pretty good, but it's hard to tell for sure from a picture if it's not a real close-up. 

[EverettShadowbrook]

Try this link. Click the image to zoom in.

http://www.flickr.com/photos/51610604@N05/4750434103/

[traveler]

These plugs look just like mine......#1 is rich, and it's due to too much fuel.....you could have a leaky carb, or a float out of adjsutment and flooding the carb, or maybe jsut a sticky float, which requires tapping on the bowl with a wooden screwdriver handle to make it quit hanging up.  2,3,4 look fine.  If the bike "pops" at all, then you know you need some colder plugs.  One heat range colder will deal with a slight lean condition.  

Gotta look at that #1 carb.

~Joe

[traveler]

My experience with Harley's and drag pipes, when using an Air/Fuel meter, was that lean engines will "yellow" a pipe with a quickness.  Have also seen bikes that were rich that turned the pipes a dark blue almost purple color.

If one really wants to know, all you need to do is get access to an Fuel to Air meter and check it out though.

I've seen the same thing you describe.  However, I've also seen an engine running so lean that it caused the headers to begin glowing, after which they turned blue.  

The reason I say it's not an accurate way to diagnose a rich or lean mixture is because of the fact that both types of discoloration are caused by excessively high header temperatures.  The temperature the header gets to is determined by the degree to which the mixture is lean or rich.  Both overly lean and overly rich mixtures can cause the headers to overheat in a wide range of temperatures, causing either yellowing or bluing of the chrome.  And the temperature that the outside of the header reaches is significantly affected by the composition/thickness of the chrome and sub-layers, as well as whether the pipes are double or single walled.  

I have to agree, though, that using an exhaust gas analyzer is definitely the best way to determine the mixture, and a plug chop is probably the next best way.  

I agree....that's why I finished what I said by jsut recommending a plug chop.  Now he has a rich carb condition.

[EverettShadowbrook]

Thanks everyone. Still seems odd that all 4 pipes are yellowing/golding at the same rate.

Will adjusting the mixture screw on #1 be enough to solve my problems? or am I ripping these puppies out?

[traveler]

turn screw all the way in until it jsut stops, then back out ONE TURN.  Pull the plug and CLEAN it.

Start and run the bike as before.

Pull the plug and check.  The airscrew and pilot jet are only for the first 1/8th of throttle, then the needles come into play until about 7/8's throttle to wide open (WOT)and 4,500 RPM....then you are on the Main jets.

Good luck!

~Joe

[EverettShadowbrook]

Thanks traveler. I'm going to double check the float height on #1 and then go on adjusting the screw. Is this a good plan or should i go straight at the screw? The #1 carb will overfill if I leave it on the sidestand with the petcock on (i never do anymore. not sure if that is a sign of incorrect float adjustemnt).

[traveler]

more often then not....yes.  Where is the leak happening?

I've had the same problem.   Could be:

1.  Float adjsutment (only go bad if someone has messed with it before)

2.  float is bad (take float off and stick in a cup of water.....if it floats it's good....if it sinks, need a replacement float

3.  Float needle isn't sealing (clean up surfaces of float needle and seat)

4.  float is sticking (again, tap on float base with screwdriver handle to get it to quit sticking)

4.  sediment between float needle and seat.  with float off bike, put cup under carb and turn fuel on, and let fuel flow out.....will HOPEFULLY wash out any crud that's keeping the float needle from sealing.

Lastly, when bowl cover is off, ensure the float moves freely without binding.  If it binds, then the pin that holds the float on will need to be smoothed out, straigtened and re-installed.

Maybe the O-ring on the float cover is leaking??


~Joe

[EverettShadowbrook]

Good info. Lots to go on here. I appreciate it! I'll report back after I get some good garage time in.