Modern Vespa

Hi all,

It's been ages!

I've got an aftermarket banana pipe on my '76 ET3 that is driving me... bananas.

It's a 2-part pipe - the main muffler and the header pipe, with a spring at the join between to keep them together. I don't know the make (came with the scoot), but the damn thing separates pretty much every few times I hit a bump (like, normal road bumps).

I don't see any sign that it's hitting the frame, and I've cinched the mounting bolts down to no avail.

I'm open to suggestions for fixing it, but my gut is it's poorly fabricated and it expands under heat in such a way that once it gets hot it works itself apart enough to *pop* apart with a sudden force.

So my questions are: any experience with this issue on your smallies, workarounds, and any suggestions for a good replacement pipe? It's a daily rider with a mild Malossi 135 build from SF scooter center so I don't want a racer pipe - but preferably something that stays together for more than a few miles :-p

Thanks!

New spring for you, no way that spring should let those pieces come apart. Also, is your pipe connected at the swing arm? There's a bolt down there....

https://www.sip-scootershop.com/en/product/racing-exhaust-malossi-power-exhaust-banana_M321443

I've had this pipe on my ET3 for 7 trouble free years. Only touched the exhaust twice with the original spring. Same one you have?

Lol, yes of course. That's the weird part - I can't see how they would have a chance to flex and disconnect... Both halves of the pipe are mounted to the same swingarm at the end of the day (one albeit through the engine). But like I said - no sign it's hitting the frame, and sometimes it will come loose with the slightest bump (although always after hot and having been ridden a bit, so I think vibration and heat expansion are the key)

Hm, link didn't work for me. Is this the one:
https://www.sip-scootershop.com/en/product/racing-exhaust-malossi-power-exhaust-banana_M3214430?cr=e993ab67-6807-4109-bbed-f6374ebf9f9b&gclid=EAIaIQobChMI9-yntbDE8QIVPHxvBB1fugNMEAQYASABEgLp4PD_BwE

It's definitely not the same one I have

Good to see ya around!

Good luck on sorting the pipe.

Yep. That link worked. Got the money for a replacement?

To check if its the spring, could you temporarily use lockwire to hold it together, the other thought was maybe some sort of exhaust putty to get more of a seal.

if we get down to it, there's only a couple ways this can happen. the silencer portion slides into the other (or vice versa, can't remember). you are either sliding out to the rear, or the outer portion is cracked and allows lateral movement. If you are sliding out the rear, the silencer portion is probably moving too freely relative to the bolt. before you put the spring on, try moving the pipe with all the bolts attached and torqued down. It shouldn't have the freedom to come apart with all the bolts in place. move it side to side, forward and back. you need to visualize how this can happen, then you can see it. it could be that the bracket at the swingarm has cracked a weld or something.

That's a good call - and it's probably a good work-around in the meantime to just cinch it on there with some stiff wire. I'm assuming it needs to be able to move a little so I didn't want to affix the two pieces too rigidly. Thanks!

have a look above, you were replying while i was

Thanks - I've cinched everything down so that nothing can be moved (reasonably) by hand each time, but I noted the silencer portion doesn't sit too deeply into the upper once the bolts are tight, and i think that's allowing things to start to get funky when it's hot and under forces. It honestly seems like the proper fit of the two gets undone by tightening the swingarm bolt sufficiently, because it winds up torquing the silencer back and downwards from being well-seated to poorly seated. So you're probably right - the bracket at the swingarm join might have a crack at the weld (I'll reinspect) or maybe the bracket itself is bent down a bit

Perfect! I might go for that then. I think so - any tips on a good starting upjet to dial in from? (still the stock 19/19 carb)

Thanks! I still live... my work life just chewed me up and spit me out for a while and I had to dig in on that to stay afloat. But I'm still riding my scoots and rolling along in one piece

I think you are on the right track now - if tightening that bolt down separates the pieces, either it needs bending or maybe shimming or some such. the pipe should fit in well even without the spring.

Hi All,

brief update - i didn't see it before because it doesn't flex easily by hand but I discovered today that indeed - large crack in the weld for the bracket that bolts the muffler to the swingarm.

I've got the Malossi recommended above coming in the mail, so hopefully i can go back to a less finicky commuter experience soon

Got the pipe on today - what a nice pipe. Firstly, the build quality feels great and it fit perfectly. Secondly, it breathes much better - scoot feels like it'll wind out forever.

Thanks for the recommendation

Got an 86 main in there and it feels happy. I started with a 92 and worked down

Anyone have a use for the old one? Looks like an SIP Road pipe - bracket needs to be bent back into place and welded. Lemme know

Good looking indeed!