Why does the Y exhaust section rust first?

[csdexter]

Howdy,

 

I just patched quite a number of small holes in the Y (middle) section of my exhaust and since this is the second set of pipes this bike had, I have to ask:

 

• why is it always the Y section? The front pipes are pristine, even still shiny. The mufflers have nothing but light soot on them. The Y section is almost completely obliterated. Why?
  

The ex set of pipes (I got the bike with a big box of parts from the PO which included the old pipes) was the same: really good front pipes, eaten beyond repair Y sections and good as new mufflers.

 

 

Any ideas why this happens only to the Y sections?

 

 

:confused24:

[Sylvester]

UHH, maybe moisture. You do have lots of that in your beautiful country and lots of it comes from the ocean with salt, why only the Y connector...I have no idea.

 

[csdexter]

Moisture, granted, but how come the front section, the heat shields (including the ones on the Y) and the muffler are impervious to it?

[dingy]

The 'Y' sections are probably single wall tubing.

On the 1st gens, the front pipes to the collector are double wall tubing. Possibly the same on RSV's.

Gary

[csdexter]

Just curious: if it's double-wall, shouldn't that mean it simply takes longer for it to corrode through? My front pipes are shiny and clean, like chrome (I mean the inside pipe, not the heat shield) while the Y section is rusty-red and basically flaking off (while the heat shield on it is still shiny like new).

[Seaking]

Its possible that the front end of the pipes being so hot tend not to stay wet long enough to rust, while the rear of the pipes are cooler, being nearer to the rear wheel spray while riding in the rains, and sit low so all the water drips down and collects near them when you've pulled over.. Hmm I'll have to pull mine off this winter to inspect them this winter..

[CaptainJoe]

If I were to "guess" ... would probably be due to the welds. The rear pipes have welds all over them and if you look closely, that's heat treat silver paint, not chrome that's covering the spotwelds and mig welds....

 

 

I know cause i just wire wheeled mine and used the same heat treat silver paint.. Rustoleum I believe...

 

Trick i learned from running two cycles, take pipe apart pour oil inside, drain and reassemble.

 

It will smoke for about 15 min but the inside will be "good to go" for a couple of years...

 

 

Also: Short trips causes condensation in the pipes that doesn't burn off and will eat your pipes from the inside out.

Edited August 5, 2013 by CaptainJoe

[csdexter]

Seaking, the distance from the front exhaust port to the Y section is about 2.5 times the distance from the rear exhaust port to the same place. The Y section should be a lot hotter than the front section, not cooler.

 

However, you're right about the slight bend in the Y section being the lowest point on the whole system and closer to the rear wheel -- but when going forward, it's the front wheel that's throwing dirt at the radiator and underside, not the front one

 

Easy Rider, your point about the welds is valid. The muffler has similar spot-welding points on it that were painted with silvery paint afterwards and still, it's not rusty (not around those spots, nor anywhere, not even on the mating surface with the Y section!). Also, if they were eaten from the inside out, the outside wouldn't be so badly corroded, right?

 

 

Now, I have a crazy idea: remember the sacrificial anode story from school? What if the metal used in the Y section pipe is acting like a sacrificial anode when connected to the other sections, obviously made up of a different metal? So, whenever things are wet, the Y section corrodes like hell while the front and rear remain nice and clean.

 

And to top it up, call me crazy if you will, but the Y section is (MSRP) priced more than twice the front pipe (which, as mentioned, is way larger), more even than the muffler itself! I smell bad things here :-(

[csdexter]

I knew I couldn't continue my argument without further evidence, so here it is:

http://gallery.dexter.linux360.ro/d/20453-2/DSC_1136.JPG

 

The lowest point of the whole exhaust system is the slight bulge in the middle-left of the photo, where the pipe weld is -- just below the top punctured region. That part should be the rustiest, but instead (after steel wool-ing the dirt away) it still has the original grey hi-temp paint on it.

 

Also, the pipe seems to "want" to rust a lot more around the brackets holding the heat shield in place than anywhere else. The heat shields are intact and the pipe sections away from those brackets, albeit dirty, still have full thickness and are almost not corroded at all. The brackets themselves appear to be made of the same sheet metal as the heat shields: chromed steel.

 

I'm out of ideas as to WHY

Edited December 1, 2013 by csdexter
Typo

[Condor]

This is just a wild a$$ guess, but are the header pipes stainless or chromed steel?? If they are SS you might have a case of Galvanic Corrosion going on with dis-similar metals. The 'Y' being one type and the tubes and brackets another.

[csdexter]

You were right on the money. The front section (header pipes) is stainless and so is the muffler. The middle section is some unknown metal. The heatshields are all chrome.

 

Now, to find a guy that's handy with welding and bending stainless so that I can reconstruct my Y sections out of stainless steel and be done with it (wouldn't pay Yamaha $500 apiece even if I were held at gunpoint).

[djh3]

Try a local muffler shop. They should have stainless muffler pipe. (most cars now have stainless) They should be able to fishmouth the pipe and make you a perty nice piece. Being it has a shield to go over it the part dont have to be show quality. Shoot Id see if they could make it a tick bigger at the union and swedge down to fit the mufflers and pipes. If you look over on the first gen side I have seen some pretty nice work arounds those fellows have goten made up to the ancestrial bike.

[Caveman]

Good call guy's.

[csdexter]

Unfortunately, my "local muffler shop" looked at the bike with disgust and then went:

"ya' pipes are small, ain't they?"

"Yes, what you see is a shield, the inner pipe a bit over an inch in diameter"

"Well, the smallest gauge me pipe bending machine can do is about the size of your shields. 'No way I'll be able to bend pipes as small as yours".

 

And we left it at that, people here seem very unwilling to get paid ... one more reason to respect the US (where, at least in the smaller and more traditional shops, they know you're the most important person in the room when you step in).

 

Will find a way ...

[TDbiker]

Last spring when I first started my '05 RSTD after sitting all winter I noticed a pinhole-sized stream of smoke coming from behind the heat shield below jug #1. I couldn't see an obvious cause so opted to take it in to the local dealer to investigate. He confirmed a hole or possibly even a crack at the "Y", so he ordered up a new one and installed it for me.

 

All I can say is I sure am glad I have an extended warranty, 'cuz it sure wasn't cheap. He was surprised it was covered (as am I), but the warranty company authorized the repair.

[relic]

Both sides of the y pipe on my 2004 were replaced under warranty a few years back.

I kind of think they are leaking again but not enough to replace yet.

Pipes are louder than normal. They are extremely expensive!!!