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Author Topic: How blue is too blue?  (Read 1312 times)

Arizoni

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Re: How blue is too blue?
« Reply #15 on: June 18, 2013, 10:30:05 PM »
The bluing is caused by heat.
The heat can be caused from the things you mentioned but it can be the result of high speed riding, even if the fuel/air mixture is exactly right.

At high speeds, it's easy for the exhaust pipe to get well over 1000 degrees F (538* C.) and chrome becomes yellow and then blue as these temperatures are reached.  There is nothing that can be done to prevent this.

If all of the riding is at low speeds while using low rpm shift points and the exhaust discolors, then consider the fuel/air ratios.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

D the D

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Re: How blue is too blue?
« Reply #16 on: June 18, 2013, 11:06:13 PM »
Goldish straw color is just right.
YAY!
By the way, don't bother with any of those coatings that you swish inside the pipe that are supposed to prevent bluing of the pipe.  They won't.  Maybe the professional ceramic coats you can send your pipe for will work, but it's not worth it to me.  Straw shows I ride.
'07 Iron Barrel Military (Deceased 14 September, 2013)
2014 Yamaha Bolt R Spec V-Twin
1975 XLCH

The_Rigger

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Re: How blue is too blue?
« Reply #17 on: June 19, 2013, 12:45:32 PM »
Frankly, I'm at a loss as to how to adjust the F/A mixture with a fuel-injected bike, or set the timing with the electronic ignition anyway...  My new Hitchcock's pipe is turning straw-gold from the head down, and I think I'm just not going to let it concern me.

...For now. 8)
-Dave
2012 C5 Special
Central Michigan, USA (when I'm not working somewhere else)

neil

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Re: How blue is too blue?
« Reply #18 on: June 24, 2013, 03:47:45 PM »
Hello Rigger:
If your down exhaust pipe is  Straw Gold color, sport that around and be glad. That is an indication the engine is running at optimum efficiency and temperature.
I read a study on the bullet mania web site from the UK, by a chap from Oxford about, the role of fuel mixture and possible over heating of these engines. I believe he is a bullet owner. After some testing under real riding conditions he concluded that a more moist fuel mixture charge entering the engine gave a mili-second of cooling during the intake stroke and more importantly during the compression stroke before the spark plug fires the fuel charge which raises the engine temperature. The fins can only do so much to cool the head and barrel. He felt the wetter charge did just enough interior cooling to keep temperature under control under normal riding. If the fuel charge is too lean, very little interior cooling of the head and barrel under the same circumstances would lead to excessive heat, bluing of the exhaust pipe, and possible seizure.
The proper fuel charge with enough moisture can make the difference between normal engine temperature  and overheating. The moral of the story is, don't run your bike when it is too lean or you will risk too high temperatures in the engine and bad results. Riding it too hard consistently at too high speeds can do the same thing.
If you suspect the engine is too hot, stop and smell the bike. A hot engine has a distinctive smell which should tell you to get off and let it cool down before you resume riding.
Don't ask me how I know !

Neil
ps. I ride Buzzy a tad rich. gas mileage is acceptable and a new plug to start out each year is not too steep a price for a cooler running bike.

   

Kevin Mahoney

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Re: How blue is too blue?
« Reply #19 on: June 24, 2013, 03:55:08 PM »
When you are flying a piston aircraft you generally take off full rich (there are exceptions for altitude etc.). As you gain altitude you generally lean out the mixture (because of the thinner air). You can lean for best power or best economy, but long story short, fuel is used to help cool these engines. I would guess the same applies to a slightly rich mixture

Guaire

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Re: How blue is too blue?
« Reply #20 on: June 24, 2013, 08:36:55 PM »
 A lean burning motor will be too hot at the head. The pipe right at the head will be getting too hot and it will show it there. A too rich motor will pass burning mixture out the pipe. The discolorization will be farther down the pipe.
  Our pipes are the 'real' pipes. Some pretty cruiser bikes are dual walled. The inner pipe is the exhaust pipe. The outer pipe is for looking good by not showing the results of combustion. We have one pipe with actual exhaust color. Unblued, uncolored pipes are not exhaust pipes. They are the outer pipes, covering exhaust pipes. Adjust your expectations accordingly.

The_Rigger

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Re: How blue is too blue?
« Reply #21 on: June 25, 2013, 09:41:35 PM »
If your down exhaust pipe is  Straw Gold color, sport that around and be glad. That is an indication the engine is running at optimum efficiency and temperature.

I suspected as much...  Long as it isn't turning blue, I'm not worrying.  I really like the bark of that upswept Hitchcock muffler, too!  Much nicer than the stock telephone pole...
-Dave
2012 C5 Special
Central Michigan, USA (when I'm not working somewhere else)

barenekd

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Re: How blue is too blue?
« Reply #22 on: June 26, 2013, 06:24:22 PM »
Quote
A lean burning motor will be too hot at the head. The pipe right at the head will be getting too hot and it will show it there. A too rich motor will pass burning mixture out the pipe.

In reality, the opposite is true. A lean mixture is slower burning than a rich one. The proper mixture is burnt in the combustion chamber, so doesn't carry as much heat out as the lean mixture, which is still burning in the exhaust pipe. That is why the lean mixture blues the pipe. It also will burn the the exhaust valve.  The reason you get popping or backfiring out of the pipe with a trailing throttle is that the  idle mixture is too lean. As the bike is running with a proper mixture, some very lean mixture, unburnable, will go out the exhaust port and will settle in the pipe. When you roll the throttle into the leaner region of idle, the mixture will once again be burning in the pipe with enough oxygen left to relight the mixture already in the pipe, then you get the loud BANG!, or a series of smaller pops.
Comes in handy occasionally!
As for changing the timing and EFI setting, unless you have some very expensive equipment, you don't. On the other hand, the way it comes works very well. You can buy some aftermarket gadgets to reset the mixture, but it's not cheap either.
Bare
« Last Edit: June 26, 2013, 06:32:42 PM by barenekd »
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fvtenfanatic

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Re: How blue is too blue?
« Reply #23 on: June 27, 2013, 07:56:07 AM »
All this talk about pipes bluing and/or turning a gold/straw color is interesting to me because my pipe is of the gold/straw color from the head down about a foot or a little more and I was recently told by another Enfield owner that it wasn't good at all for it to be that way or I won't be able to properly tune my new Amal, which seems to be running way smoother and stronger then the stock Micarb did. Now I am hearing here that as I thought the straw color is good.

Damon
2005 Bullet Continental

Bulletbaz

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Re: How blue is too blue?
« Reply #24 on: June 27, 2013, 08:28:27 AM »
I think that the guage (wall thickness) of the pipe is also a factor here. When I recently changed the original header pipe of my Sixty5 to an aftermarket one (which was of a much thinner guage) and didn't change anything else that might have affected it (same muffler, jetting, timing, etc) - there was considerably more blueing at the first six inches or so.   

GreenMachine

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Re: How blue is too blue?
« Reply #25 on: June 27, 2013, 10:05:14 AM »
I purchased my bike in the winter months and when I was breaking it in I noticed that on occasion it would get cherry red hot about 6-8  inches down and after cooling it was a deep blue hue color... I installed the 50 style Brit exhaust and rejetted.  I polished out the blue the best I could and since then it's maintain a straw color...My plug looks perfect and the bike runs fantastic...The carb bikes were set up lean...IMO straw color exiting the header down 6-8 inches is normal for these bikes.
Oh Magoo you done it again

barenekd

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Re: How blue is too blue?
« Reply #26 on: June 27, 2013, 11:50:59 AM »
The straw color is fine. It's cooler than blue!
Bare
2013 Moto Guzzi V7 Racer
2011 Black Classic G5 (RIP)
I refuse to tiptoe through life only to arrive safely at death
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