Exhaust Turning Gold

[toman21]

It only starts to turn gold when the bike gets really hot, say when riding trails. Its turning gold at the bit where i had previously burnt my waterproof trousers on and had to rub for ages to get the shinny chrome again when metal polish. Want does this coloration mean? I have read that blue means lean and gold means rich not sure about that though.

Edited January 1, 2014 by toman21

[nh014]

A common myth is that blue is lean and gold is rich (or the reverse). Gold and blue pipes result because the exhaust is running too hot.

There are three reasons for this. The first and most common reason is that the bike is running lean. A lean mixture causes exhaust temperature to rise very sharply. A slightly rich mix normally will not cause blued or yellowed pipes.

Second is the quality and thickness of the chrome and the steel and how quickly the exhaust pipe dissipates heat.

And third is of course how hard the the bike is being ridden. Extended periods of wide open throttle (not likely on a trials bike) will obviously create more heat.

Edited January 1, 2014 by nh014

[toman21]

Yeah, when it went gold i was riding it near flat out for a while. The bike was running on the lean side at that point aswell, also i think i had rubbed all the chrome off which didn't help Since then i have when up on the pilot jet number to get it on the slightly rich side which i think is a safer bet.

Thanks for the info

[tony27]

Different colours are caused by the heat that the exhaust gets to, when heat treating metal using a flame you can see the colour of the metal changing as it heats up & you use the colour change to judge when you're at the required hardness & stop heating

[jse]

A common myth is that blue is lean and gold is rich (or the reverse). Gold and blue pipes result because the exhaust is running too hot.

There are three reasons for this. The first and most common reason is that the bike is running lean. A lean mixture causes exhaust temperature to rise very sharply. A slightly rich mix normally will not cause blued or yellowed pipes.

Second is the quality and thickness of the chrome and the steel and how quickly the exhaust pipe dissipates heat.

And third is of course how hard the the bike is being ridden. Extended periods of wide open throttle (not likely on a trials bike) will obviously create more heat.

And a little trick to scrape off burned on clothing material is to use a piece of sharpened copper (I use a piece of flattened copper pipe). The copper will scrape off the gunk and as it's softer, will not take off the plating with it.

Jon

[taffe]

This happened to my Harley whilst riding across the Nullabore Plain in Western Australia, it was only the rear muffler not the pipes. I checked this out with the Harley Davidson tech's at the rally I was heading for, and was informed that due to the constant riding in a westerly direction and the wind coming off the sea from the south [the pipes are on the other side of the bike] and the fact that the front muffler exits gasses past the rear muffler it got very very hot and turned gold.

I can buff it out but gold is good.

Cheers Taff

[dadof2]

Just a thought for those with titanium (expensive) exhausts. Coloration is a sign that the exhaust is hot enough to react with oxygen in the air. As titanium absorbs oxygen it becomes brittle and will crack. If your titanium exhaust colours change your jetting and or riding style.