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Red glowing S-header

Classic Norton Commando Motorcycles.

Red glowing S-header

Postby rivera » Thu Apr 20, 2017 12:01 pm

Today I tested my charging system too look for lost energyon my 1970 Commando S type.
After a night ride with mostly high-beam on the battery was flat.

After charching the battery I had the bike running on it´s mainstand and revved it up to 3000 -4000 rpm after warming up.
A test ride was not possible because of a dropback to winterly conditions here in Germany.

Test was fine so far but I stopped it because the right hand header was glowing red!
It was discoloured before. The left header shows only minor discolouration.

Normal because of the narower curve of the S-exhaust sytem or something wrong with carb adjustment?
Bike runs fine and has a good idle at 1000 rpm. Boyer-Ignition is timed correctly. 2 Amal 930 carbs.
Any thoughts, gentlemen?
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Re: Red glowing S-header

Postby edgefinder » Thu Apr 20, 2017 1:17 pm

The first time I got my commando running it sounded good but in less than a minute one pipe was glowing. I had to remove the press in plugs on bottom of carb bodies to clean a bunch of debris in pilot jet cavity. Drilled small hole, small screw to pull cap, epoxy cap in. Try spraying carb cleaner after cleaning pilot jet and see if it comes out the progression hole.

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Re: Red glowing S-header

Postby norton73 » Thu Apr 20, 2017 3:21 pm

Low battery charge and a Boyer equals a ton of ignition advance.
I once had the battery on my '73 fail while riding and as the bike started to miss fire, I looked down to see one of my headers cherry red. A new battery resolved all problems.
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Re: Red glowing S-header

Postby xbacksideslider » Thu Apr 20, 2017 5:54 pm

A glowing head pipe means that you are at risk of burning a valve, check fuel mixture and ignition timing.
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Re: Red glowing S-header

Postby Torontonian » Thu Apr 20, 2017 6:10 pm

Yes ,do not drive it until issue is resolved.
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Re: Red glowing S-header

Postby BillT » Thu Apr 20, 2017 6:59 pm

Glowing exhaust usually means lean mixture or retarded timing.

If one side only, then lean mixture on that side is the likely culprit

lean mixture can be caused by too little gas (plugged jet, dropped needle or clogged filter) or too much air (vacuum leak or unbalanced throttle cables)
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Re: Red glowing S-header

Postby Torontonian » Thu Apr 20, 2017 7:12 pm

Yes the danger if driven is a burnt/seized valve or piston damage on that side. Likely pilot jet or needle clip popped off. Also a gentleman does not ride after dark !
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Re: Red glowing S-header

Postby texasSlick » Thu Apr 20, 2017 7:24 pm

BillT wrote:Glowing exhaust usually means lean mixture or retarded timing.

If one side only, then lean mixture on that side is the likely culprit

lean mixture can be caused by too little gas (plugged jet, dropped needle or clogged filter) or too much air (vacuum leak or unbalanced throttle cables)


+1

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Re: Red glowing S-header

Postby rivera » Fri Apr 21, 2017 1:01 am

Ok will check that! Thanks!
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Re: Red glowing S-header

Postby gripper » Fri Apr 21, 2017 3:11 am

Will not a over advanced spark give red exhausts too?

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Re: Red glowing S-header

Postby BillT » Fri Apr 21, 2017 3:24 am

gripper wrote:Will not a over advanced spark give red exhausts too?


Yes it could, but would be a bear to start an over-advanced engine - you would keep getting kick-back.
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Re: Red glowing S-header

Postby texasSlick » Fri Apr 21, 2017 7:25 am

gripper wrote:Will not a over advanced spark give red exhausts too?


I have to disagree with others on this .... over advanced spark will make the internal (inside the cylinder) temperature higher than normal, but the exhaust temperature may be less than, normal, or higher than normal.


The reason overly retarded timing affects exhaust gas temperature is because fuel takes a finite time to burn. With overly retarded timing, fuel is still vigorously burning as it passes into the exhaust ports and headers, raising the exhaust gas temperature, but the internal cylinder temperature is lower than normal, since less fuel was burned in the cylinder as compared to normal timing.

With overly advanced timing, virtually all the fuel burns in the cylinder. This causes a slight increase in cylinder temperature as compared to normal, because a small amount of burning fuel leaves the cylinder with normal timing. However, a larger temperature change occurs in the cylinder with overly advance timing because the first fuel to burn is working against the crankshaft rotation. In effect, the other cylinders must put work into the cylinder to turn the crank past TDC. This additional work input raises the cylinder temperature higher than normal. The exhaust gas temperature is not so predictable.

In short, with late timing the header pipes run very hot because fuel is burning get in the headers. With very advanced timing, the exhaust temperature is reflecting the events inside the cylinder.

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Re: Red glowing S-header

Postby dynodave » Fri Apr 21, 2017 8:52 am

Air cooled MC such as our Nortons...
A glowing pipe at night is normal and IMO desired and an indicator your bike is running good or great.
The problem is most people, based on the responses here, don't know what really is normal.
A night time very dull dim red is acceptable but a bright red seen in the daylight is no doubt a precursor to a melt down.
No color at all... ever... is a very rich cold running engine (sub 900deg f EGT ) and is way down on power and crappy gas mileage.
Your engine if running well, the pipes will blue... but chrome that stays pure chrome is cold.
If you dyno an air cooled engine, only use a brake dyno :!:

Bikes like my liquid cooled Ducati can use a inertia dyno, but on my brake dyno, the pipe is a much brighter red then the norton can stand.
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Re: Red glowing S-header

Postby rivera » Fri Apr 21, 2017 9:54 am

I guess it is a carb adjustment problem. Here are the plugs:
The left plug in the pic is from the right cylinder and vice versa.

Image
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Re: Red glowing S-header

Postby peter12 » Fri Apr 21, 2017 10:38 am

Left plug too rich, right plug looks ok to me but difficult to tell in picture, maybe lean.

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