Red hot headers

[JScro]

So now that I'm feeling more comfortable about my bike, I've been riding at night. My normal warm up procedure is to choke it, let it warm up, and then walk outside and turn off the choke when I hear the idle increase. This evening I noticed my headers were glowing red hot after idling for no more than 5 minutes.

Turned the choke off, and they went back to normal pretty quickly.

Is this anything to be concerned about or normal? I'm sure it's been doing this every time I ride, I just haven't noticed it in the daylight. The bike has the Mac 4 to 2 exhaust.

[ddragon63]

how high of an idle? (how many rpm) and what is the temp outside? glowing headers is usually caused my a lean condition or severely retarded timing. If you left it on high idle (mine is about 4000 rpm full choke) sitting still in the cold it could create a lean condition and cause the headers to glow. I use to have that problem with a old quad in the snow.... moving slow @ high rpm in cold made the headers glow. one up to speed or rpm decreased it faded back...

[fredintoon]

It's the MACs what's doing it.

- - - This evening I noticed my headers were glowing red hot after idling for no more than 5 minutes.
Turned the choke off, and they went back to normal pretty quickly.
Is this anything to be concerned about or normal? I'm sure it's been doing this every time I ride, I just haven't noticed it in the daylight. The bike has the Mac 4 to 2 exhaust.

Hi JScro,
If double wall stock pipes get red it's time to start worrying but it's OK for single wall pipes like your MACs to glow dull red in the dark when parked idling with the choke on. Us geriatrics use the location of single wall pipe discoloration as a tuning aid.

[TomB]

how high of an idle? (how many rpm)

Check out this for high revs glowing pipes

Seriously, it gets the idea across. I have my Kerker headers painted black, I always start the engine and set off gently, the flow of air across the headers stops the paint burning off, if I run the engine for any length of time stationary the paint burns off.

That may be worth trying for folk that have an issue with single skin chrome headers blue-ing.

[JScro]

Idle is usually about 4-5k when I make it outside to turn it off (it rises quickly) and it was really cool and windy outside last night.

Didn't think I needed to worry, just wanted to be sure though.

[trbig]

JScro...

What Fred was saying, or asking maybe, was if you had the stock header pipes on your bike, or if they are an aftermarket exhaust such as Jardine, Mac, or such. Aftermarket pipes are just single walled steel and will glow. If they are still the stock header pipes, they are a double walled construction. If those were glowing red, then yes, you've got a problem.

[fredintoon]

JScro...

What Fred was saying, or asking maybe, was if you had the stock header pipes on your bike, or if they are an aftermarket exhaust such as Jardine, Mac, or such. Aftermarket pipes are just single walled steel and will glow. If they are still the stock header pipes, they are a double walled construction. If those were glowing red, then yes, you've got a problem.

Hi Tr,
Jeff's first post sez he's running MAC 4 into 2 pipes so yes, he's fine.
But as you say, if you have dual wall pipes that show red at night, you got a problem.

[trbig]

Sorry, I didn't see that at the end of his post..

[TopCatGr58]

Sorry, I didn't see that at the end of his post..

Put your reading glasses on Tod, and then you'll be able to see things like that!
"inside joke"!
T.C.

[Joab]

Aww crap. Then I have a problem.

[ddragon63]

check your timing.... if your timing is too low (retarded) it will cause header glow due to fuel burning in pipe rather than igniting inside combustion chamber. your vacuum advance is suppose to keep this from happening under light load and low rpm. Check an make sure it is working properly. JAT

[cywelchjr]

check your timing.... if your timing is too low (retarded) it will cause header glow due to fuel burning in pipe rather than igniting inside combustion chamber. your vacuum advance is suppose to keep this from happening under light load and low rpm. Check an make sure it is working properly. JAT

Vacuum advance does not kick in till you come up off idle, it's ported vacuum and there isn't any to speak of until you come up off idle. At idle if it was getting full vacuum it would bang itself to death, as it pulses really heavily at low RPM, but smooths out as RPM goes up. Your timing should be sufficient to prevent what your talking about at idle without any vacuum advance unless you have it set wrong, you actually don't want it too much further than the 5 or 10 deg it starts with in many cases for smooth idling anyways.

[ddragon63]

Vacuum advance does not kick in till you come up off idle, it's ported vacuum and there isn't any to speak of until you come up off idle. At idle if it was getting full vacuum it would bang itself to death, as it pulses really heavily at low RPM, but smooths out as RPM goes up. Your timing should be sufficient to prevent what your talking about at idle without any vacuum advance unless you have it set wrong, you actually don't want it too much further than the 5 or 10 deg it starts with in many cases for smooth idling anyways.

ya but he's talking hi idle 4 to 5000 rpm on full choke... you'll pull alot of vacuum up there. plug a vacuum gauge in and try it you'll be surprised. My old race car made 4.5 hgs vac @ idle 1300 rpm. but sitting still bring the throttle up to just 3000 it would make 26 hgs that'll open your timed port every time

[cywelchjr]

ya but he's talking hi idle 4 to 5000 rpm on full choke... you'll pull alot of vacuum up there. plug a vacuum gauge in and try it you'll be surprised. My old race car made 4.5 hgs vac @ idle 1300 rpm. but sitting still bring the throttle up to just 3000 it would make 26 hgs that'll open your timed port every time

These bikes don't have a choke. Unless the carbon is adjusted wrong. The port in the car is still covered, ass the "choke" is really an enriched that doesn't move the throttle like an automotive choke does. And yes, I've watched on mine with full "choke" and no vacuum advance happens. You have to open the throttle plates on a properly tuned bike to get any vacuum advance (improper tuning which uncovers the port is one of the causes of hanging idle caused by vacuum advance being applied when it shouldn't be).

[motoman]

(improper tuning which uncovers the port is one of the causes of hanging idle caused by vacuum advance being applied when it shouldn't be).

..........or vice-versa with idle mix screws open too far and idle adjustment lowered causing a stumble with the lagging behind vacuum advance from a delayed throttle plate opening exposing the ported vacuum ......and a rich idle circuit........hmmmm.......(no comment please CY).