Modern Vespa

9K miles. clean break around the pipe. See pic. Any thoughts on repair versus replace? I'd rather not invest in a new exhaust right now if I don't have to.

A muffler shop should be able to weld it.

If you are going to ride it to the shop OK.

If you want to take it off and take it separately to any welding shop, mark it with a piece of chalk in two places before you take it off and take pictures from above or below.
OR place a piece of paper under it and trace the outline of the muffler and the pipe.
These will help the welder align it properly so it fits when you get home.

Not a tough fix.

Really need to leave the exhaust in place and have it tacked. Then remove it and have the weld finished. That's the only way it will align properly.

Had the same failure years back, repaired it as described and it has worked fine since.

Good luck with it.

R

I almost certainly would have removed the exhaust to take to the shop without thinking about alignment. Thanks, that is great advice!!

If repair doesn't end up an option, I'd recommend looking for a used part. My exhaust rusted off my bile in June and I was able to pick up a new on for $100. I found it on eBay.

Yup, same here, to keep them around I encourage upgrading from OEM.

I'd be concerned to find out why the exhaust broke in the first place; did any of the muffler bolts come loose or fall out? If not, the header pipe may be misaligned and stressing the pipe on the muffler. When you reinstall the pipe, you may want to loosen the two nuts on the header when you put it all together, make sure it's lined up with the muffler pipe, then re-torque the header nuts to the proper torque settings (very important!) Good luck!

Are you using a bronze muffler bearing, by any chance?

"Muffler-farmer "

That break looks like the result of use of an other than stock graphited sleeve.

That or a one-piece welded-up muffler. The only other time I've seen this was on an exhaust where the normally-gasketed joint was welded together. As the now-solid pipe heats up and cools down, the whole thing shrinks and pulls the can toward the front. Eventually, the next-weakest spot breaks.

Turkman ran with a welded up OEM for tens of thousands of miles before joining the LV Army. To my knowledge his OEM pipe is still uncracked, but my LV cracked at almost the same spot (unweldable)

Based on your theory (which you shared before I think) I now occasionally loosen the three rearmost mounting screws at the swingarm (LV) when the system is hot, and let it cool then re-tighten in the morning.

My theory is that allows all the parts to relax back to an unstressed state. Again, just my theory and an unscientific one at that. Don't know if it works, but it helps occupy a few minutes of time and makes me feel scooter-productive

Ouch if this is #2 break!

brilaz, did you hit some type of horrific pothole recently?
(I don't see both problems being caused by the bushing or thermal expansion/contraction at the same time)

It would be a combination of the two -- the natural expansion / contraction, and the fact that the muffler bearing doesn't allow anything in the system to "give".

Considering the condition of many of the roads in the bay area, I would consider it a certainty that a pothole was hit at some point or another.

And for love of all that is Vespa, when you take your pipe in to be welded, bring the header pipe with you as well, and ask them to remove that brass muffler bearing so you can go back to a stock one.

I was speaking in terms of the pipe and the studs breaking concurrently....seems like a lot of trauma in a short time on one isolated exhaust system to be caused by thermal expansion alone.

I'm thinking trifecta...the perfect storm; heat/cool effect, unforgiving brass bearing and some type of traumatic impact causing that combination of damage.

Exhaust forensics 101!

Ah.

scooter runs very lean and the welds tend to fail, hot spots can cause lots of problems in all kinds of things even boiler tube is prone to fail at the weld or close to them.

True, though the full-on intensity of the heat doesn't generally make it all the way to the can.

Good Idea. When re welding the unit ask to have at least one gusset added.

Example

The reason for the graphited sleeve in the exhaust pipe is to provide an expansion slip joint for the heated pipe so as not to pressure load the exhaust port studs.

That's cheap for a new one. I got a used for $50 plus S&H. Yes! It's a brand new project.

Some history on my problem. First, yes, I had the bronze bushing installed back in May. About a couple months after that, I brought my bike in for the fuel-pump recall and the dealer reported an exhaust stud was broken and that it came in to them that way.

Well, perhaps it did come in that way, but was quiet before I brought it in and was now really loud, and they did remove the exhaust to replace the fuel pump, so it was hard for me to prove how the studs were broken. Dealer refused to fix that, so I brought it back to the shop that installed the bronze bushing and they fixed the exhaust studs for free (though they of course suspected it was broken by the dealer). That was standup of them.

Then this crack happens about a month later. I've had nothing but problems since that bronze bushing was installed. Was considering replacing it with OEM as part of all this.

Thanks for the advice to check ebay for used exhaust. I'm going to see if it can be welded first before I go that route.

Why on earth did they remove the exhaust? It swings down out of the way with the rest of the engine.

>Considering the condition of many of the roads in the bay area, I would consider it a certainty that a pothole was hit at some point or another.

I don't recall any large (or even small) pothole mishaps, but it is possible I hit one and don't remember. The roads I travel every day are in pretty good shape actually.

I would strong recommend you remove the exhaust and NOT TACK WELD IT. They use electrical current for this process and you can Fry your computer. Others chime in here if you disagree....Tim

Oops, I see louisq posted my post from the other thread where I explained about the bronze bushing. Sorry, you all are way ahead of me. I've been too busy to check back here until this morning. I'll wait for a reply on the risk to electrical before moving forward with the weld.

>Why on earth did they remove the exhaust? It swings down out of the way with the rest of the engine.

I don't know, but that is what they told me.

I have been told that if you unhook the battery you can weld and not hurt the electrics. I fabricated my own variator tool and mig welded it together while on the bike with no ill effects. YMMV

Any welding shop should have a pulse quencher they put across the battery. Alternatively the battery can be disconnected and the +ve and -ve wires shorted out.

I generally disconnect the battery and also disconnect the ECU whenever I have to weld in-situ. So far, so good.

VR? Or does that get disconnected via the battery?

Once the battery is disconnected, the voltage regulator should only be electrically reachable via ground, which is theoretically okay. Stranger things have happened, of course, but I've had no problems so far.

I took the pieces down to a local muffler shop and had it welded back together for $30. Just put it back on. Works great!

[edit]

Forgot to mention I ended up not worrying about the alignment. The alignment was pretty obvious by the way it was broken. There was really only one way for it to fit back together.

Another happy ending.

Until it fails again.

Really, the muffler bearing switch caused this problem? I changed mine 10K ago and haven't had any problems with it. I thought that this was a good fix that a lot of people here had done.

For the most part, it's a good fix. But it shifts the stress to other surrounding parts, which increases the chances that those other parts will break. Sometimes they do, sometimes they don't.