Question

[robin]

What would make stock pipes turn blue?
Maybe leaving the choke on to long?
Looking at a standard with 15,000 on it bone stock but the pipes are blue just wondering.

[Michvalk]

Sitting and idleing for long periods of times maybe

[trout dude]

Robin dose it run good now I've never saw stock pipes blue because of the double wall pipe thats why all the after market pipes blue and gold because they are single wall  hope you get a answer soon
  Who Dat

[Spirited-6]

Robin dose it run good now I've never saw stock pipes blue because of the double wall pipe thats why all the after market pipes blue and gold because they are single wall  hope you get a answer soon
  Who Dat
[Stock pipes would have to get VERY HOT, did I say VERY HOT to blue. I have seen this, beware !

[Clark]

NOPE.. just the opposite.. leaving the choke on makes it run rich. pipes turn blue from runnin too lean

[Spirited-6]

NOPE.. just the opposite.. leaving the choke on makes it run rich. pipes turn blue from runnin too lean

Hey Clark. What book are you reading ? I missed that one. ...  :-)

[Clark]

wellll..maybe Harleys are different then.. my pipes on my stroker sportster turned blue from runnin to lean.. am I CRAZY???

[robin]

The owner now bought it with the pipes blue already ,the bike only has 15,000 on it he says the owner before him road it hard.
I still want to know why the pipes are blue.

[BonS]

Too rich and the mixture doesn't completely burn in the cylinder and it continues to burn in the exhaust pipes and overheats them. Too lean and the cylinder/piston/valves overheat which can conduct into the pipes and also turn them blue as well as fry the cylinders.

[Clark]

I am thinkin Bon knows what he's talkin about.. that said a dYno tune may just be yer BEST FRIEND.. especially the closer you live to sea level

[Master Blaster]

Too rich and the mixture doesn't completely burn in the cylinder and it continues to burn in the exhaust pipes and overheats them. Too lean and the cylinder/piston/valves overheat which can conduct into the pipes and also turn them blue as well as fry the cylinders.

Winner

[donaldcc]

 
  When I got my 97' tourer about 4 years ago it had blued cobra 6 into 6 pipes. after a couple years I wanted to try OEMs so I bought  set on ebay and they came with blue.  about a year ago I bought a 10 year old set of OEMs that were taken off at about 200 mi and are unblemished.  Got a deal for $250 on craigslist from a girl whose dad had them in garage the entire time and just wanted to get rid of them.

  haven't gotten around to changing.  I don't mind the blue, looks like bike has someone that rides it! 

[Cracker Jack]

Another theory, I believe the bluing with the choke on is from the increased idle speed with the bike at rest rather than from the richer mixture. The richer mixture actually helps to cool the exhaust.

The hottest exhaust comes from a perfect mixture with no excess air or fuel. Remember when the Nascar engines would burn a hole in a piston in a few seconds when they would run out of fuel? The engines would normally run rich but would go through a brief lean period when the fuel ran out.

"C" Word Jack

[chauffeur]

Barber Vintage Motorsports Museum in Birmingham has a Standard on display.  There is only 10 miles on the bike and yet there is some blueing and discoloration on the exhaust.  I'm not sure what to take from that; just found it another piece to the blueing puzzle.   

[Jess from VA]

If the bike was in the North.... too many people start it up in the garage in the Winter and let it run for a half hour, forty minutes (HOT), thinking they are helping the bike. 

[donaldcc]

Barber Vintage Motorsports Museum in Birmingham has a Standard on display.  There is only 10 miles on the bike and yet there is some blueing and discoloration on the exhaust.  I'm not sure what to take from that; just found it another piece to the blueing puzzle.   

i'm certainly no expert, but that seems VERY odd!

[BonS]

Another theory, I believe the bluing with the choke on is from the increased idle speed with the bike at rest rather than from the richer mixture. The richer mixture actually helps to cool the exhaust.

The hottest exhaust comes from a perfect mixture with no excess air or fuel. Remember when the Nascar engines would burn a hole in a piston in a few seconds when they would run out of fuel? The engines would normally run rich but would go through a brief lean period when the fuel ran out.

"C" Word Jack

Yes, a perfect stoichiometric mixture mixture burns the hottest - but - an excessively "fat" or rich mixture burns slowest and may still be burning as the piston pushes it out of the exhaust valve. The burning mixture in the exhaust pipe is the reason for the extra temperature that causes bluing.

Normally, mixtures are a little fat and leave a "wet" layer in the combustion cylinder walls. This wet layer serves to protect the engine internals from the heat of combustion. A lean mixture burns away all the wet layer interface.  When this layer is missing the heat of the mixture - even though it's cooler - directly heats the engine components - and results in overheating components and holing pistons.

[Dave Weaver]

Robin...I bought a used Tourer a few years ago that had been sitting for 3 years.  When I went to pick it up, it would hardly crawl up the ramp onto the trailer.  I took her home, removed the fuel tank and proceeded to feed her Techron, Seafoam, Fuel  mixtures all while sitting idling in the driveway.  I finally got her running right after a while, but the stock pipes on that bike blued from sitting there idling with no airflow to cool them off.