exhaust manifold pipe glowing

[hunterfett]

Hi just started my 1983 GS125 today and I've noticed after running for a short while on fast idle the exhaust downpipe from the head started glowing bright red. I'm new to the world of bikes but I have never noticed this before is this normal and if not does anyone know why this might start happening now I'm no mechanic so have not tampered with anything just a little confused any help greatly appreciated thanks
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cheers all

[kestrel]

If the bike is down on power as well then I'd take a guess at the exhaust valve not seating correctly, compression test would be the first move.
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[hunterfett]

Can this happen on its own because like I said before I haven't touched anything on it and I've never noticed it before
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cheers all

[stinkwheel]

Does happen. Especially if the bike has been fast idling and revving while stationary. More prone to it if there is flash rust over the surface of the header pipe and obviously more easy to see if it's dark.

So if it had been idling away stationary for a while with a slightly rusty pipe in the dark. Normal.

If it was after a run or only being run for a short time or obviously glowing red in daylight, I'd be more concerned.

In any case. Quick and easy to check the sparkplug electrode colour.
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[bikenut]

also check ign advance ( to rule that out ) .........
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nuts about bikes

[motad_uk]

if its an aftermarket system with a single skinned downpipe and you are running the engine whilst stationary - the pipe will get very hot and glow (its got very hot gas inside it!)

exactly the same will happen with the original double skinned pipe- its just got a pipe on the outside stopping you seeing it

if it has suddenly started happening- get it checked out

but I suspect you have just noticed it and as soon as you start riding the air will cool the pipe (and don't think about checking it whilst riding- look where you are going instead)
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[hunterfett]

Yes I did notice it in the evening hadn't used it for a couple of days and battery was flat so bumped it and left it running for a bit with choke open to recharge the battery a bit. Rode it to work this morning and it wasn't glowing when I got there. Thanks for all the advice will keep an eye it she is an old girl after all (1989). pmsl I take it from that comment you have encountered people that would be stupid enough to ride along staring at their exhaust pipe. Lol
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cheers all

[Ed Case]

Quite probably far to 'lean' a fuel/air mixture.

[stinkwheel]