Strange Blueing of Exhaust Pipe

[GarnZ]

I purchased a TX500A about 3 months ago.
I notice some blueing of the exhaust pipe in an unusual area.
It not quite blue, but it's heading that way, with the usual mottled straw colouring.

The strange area where this has happened or is still happening is ahead of the LHS muffler clamp.
That is, just before the header pipe gets to the muffler. Just about where your Left boot goes!
The top of the headers look fine, with just a touch of "Straw" colouring.

Any ideas, anyone noticed similar discolouration in this area?
RegardZ.

 

[NONclow]

Not a 650, but a Yamaha sooo... ignition could be advanced too much, carb(s) may be running a bit lean, possibly a hot spot where the headpipe meets the muff. Not sure about the 500 but if the pipes are double walled like the 650, they meet before the muffler, hence more material to retain heat.

 

[Paulrxs650]

I would say a thinner spot in the wall

 

[GarnZ]

Thanks for the replies. I'm a bit reluctant to remove header & exhaust pipe at this stage. The exhaust/ muffler doesn't look or sound corroded.
I know tappets are good.
I'm thinking the discolouration maybe due to the excessive fuel/ oil, from a previous leak, along with oil leaking from a head fault that I will be attending to at a later date. I did noticed remnants of some heavy staining down the alloy cover leading toward the gear-lever, foot-peg and the LHS header/muffler connection. Or it is near the area where a leak from the oil filter would drip. I'll keep my eye on it and see if it worsens. I did have to line the tank because of leaks on LHS, just a few months ago. I'll also see if any exhaust gases are escaping from that connecting clamp.

RegardZ.

 

[NONclow]

Since you've only had it for the last 3 months, how did you find it? A barn find, sitting for a while? Or as a daily rider? If it sat for a length of time there could be a small obstruction (mouse nest, or what is left of one) in the muffler. I'd remove it and inspect. If you remove it carefully you should be able to reuse the gasket.

 

[jayel]

Thanks for the replies. I'm a bit reluctant to remove header & exhaust pipe at this stage. The exhaust/ muffler doesn't look or sound corroded.


RegardZ.

if it's the typical yamaha double wall pipe it could be broken internally, look for a couple of small 1/4 or less hole in the header up by the port clamp and near the ex-pipe muffler joint, if you can feel air puffing from these holes when the bike is running the inner pipe is broken

 

[GarnZ]

Nonclow & Jayel thanks for the responses.
Javel, I have felt a continuing puff of air around the area you mention. I thought this is just a drain for condensation? I'll check later to see if it's both sides.
I felt it when I was bare footed beside the bike with a running engine... I did think it was strange!
RegardZ

 

[GarnZ]

Well I checked out those drain holes and they seem the same both sides, just a gentle puff when engine is running. I believe this is correct!
It doesn't seem to be getting worse and there seems to be no leaks around the area of the header/ muffler connection.

If you look at this pic, you will see where, when I purchased the bike it had a leaking fuel tank and oil leaking from head.
You can see just make out a trace, where it has taken the clean lacquer from the LHS casings. It was pretty bad!
You can also see the discolouration mentioned, which is in line with the centre of this defect.

I does appear to me that this was the problem. Thanks again for all the comments and suggestions.
RegardZ.