Modern Vespa

My apologies if this topic has been done to death, but I couldn't find anything about it in a search. Unless my hearing has dramatically improved, it seems like my GT has gotten a LOT louder in the last couple of days. Ordinarily I'd be poking around the exhaust system, but it happened so quickly that I'm wondering if there might be other culprits. This is the third year I've been riding this scoot, and it's the first hint of any kind of trouble I've had...

Thanks for any insight you might have!

I would check the exhaust gasket for failure. With your scooter on its centre stand and the engine running, if the exhaust gasket has failed you will feel hot exhaust leaking at the gasket. This is likely the cause of your scooter suddenly getting louder. It needs to be fixed soon because the heat from the exhaust can melt the rear brake line.

Thanks a million for the quick answer, Benito. I'll be heading out to the garage soon to test your theory, but this sure sounds like the culprit. This scooter is ordinarily so quiet that the difference in volume was startling, and a hole developing somewhere didn't make sense, because I would think that would cause a more gradual increase in the engine sound.

When the rear wheel needs to come off, the person doing the service needs to use a new gasket if they take the exhaust off or else this can happen. Or if they do not put the gasket on correctly this can also happen. It was much more common to the GTS which runs hotter than the GT, but it did happen to my GT when the gasket was not secured and placed correctly after a rear tire replacement.

How hard is it to replace this myself? Any special tools required?

No special tools, but do make sure that all traces of the old gasket are removed and the pipes are clean and smooth. The gasket (graphite collar) is designed to allow the pipes to slide relative to each other to compensate for expansion. The newer ones are only half covered in graphite leaving wire mesh exposed at the other end - the graphite bit is the end that is inserted first into the silencer.

Thanks again to both you and Benito...I checked underneath the scooter, and sure enough, I can feel exhaust puffing out from where that gasket is. I just ordered a new one from Athens Scooter Co., although I'll probably have the folks at Capital City Scooters swap it out. They told me they had another Vespa come in with the same problem...AND the blown-out rear brake line, which you guys saved me from.

I can't say it often enough...this forum is an amazing resource, due to moderators like you. Thanks!

P.S. Why the heck is that sleeve called a gasket? I always thought a gasket was a seal between two surfaces, not straddling them...

I prefer to call it a 'collar'. This is how the better translated manuals refer to it. if someone says 'exhaust gasket' to me I think of the gasket between manifold and downpipe.

Just wanted to follow up on this. As you can see, this sucker was blown and ready to allow hot exhaust to blast out my rear brake line:



Thanks again to JimC and Benito for keeping me off the scooter until I got this fixed!

I think you'd be better off getting the muffler bearing.

Muffler Bearing Installation

I saw that when I was initially investigating this problem, but my use of the past tense in my last post was meant to indicate that I've fixed it already. And by "I've fixed it" I mean "my aircraft mechanic/motorcycle enthusiast brother who happened to be visiting last weekend fixed it". Because I watched him (and helped align the muffler on those three bolt holes when he was done...there's a job that must be a bear if you're doing this solo), I take slight issue with the notion that you don't need special tools. He had hex wrench sockets that he could put on extenders to get to those muffler bolts, and that's sure not part of my basic tool kit. You can do it with the "zillion hex wrench sizes on a common handle" thingie I've got, but it would be a LOT harder...

Glad you were able to fix it and now can rest assured that your rear brake line is still in tact.

So I've developed a similar problem. Muffler got significantly louder except I do not feel any exhaust leaking. So hopefully an easier problem?

You checked at the graphite bushing slip joint and also up at the cylinder exhaust manifold connection?

What year is your GT? The early ones didn't have a graphite collar, the whole thing was just one piece. If one of these starts getting a lot louder, it might be holed. The other thing to consider is the SAS (secondary air system) pipe - those can corrode as well, and will make a loud noise.

2007.

I just ran my hand underneath the muffler and didn't feel anything.

A 2007 should have the graphite collar, shown here (part number 2):

Here's the SAS pipe (#3). There's other stuff related as well, see the parts list.

jimc thank you very much.
I took a picture from beneath. Does this tell you anything? Because I see nothing obvious wrong.

The graphite collar is underneath the clamp - it usually first breaks down just where the three slots in the muffler can be seen at the muffler end of that clamp.

When the bike is cold, start it, and immediately feel around those slots, and at the other end of the clamp - all before it gets too hot, which happens in a few seconds.

If not there, then either the muffler itself is holed, or the SAS pipe is holed. The SAS pipe is the most probable.

I just had the same thing happen to my 2006, got really loud after running WOT for a while. Exhaust gasket failure. When you get the gasket it's an easy fix if you have a socket set, ratchet and Allen key sockets.

I just tried again and feel a very subtle wind from this area. Very subtle.

Just a bit is enough to make quite a noise! Order two gaskets...

Is it an easy repair? I'm mechanically inept.
Which gaskets?
Can I safely scoot around without further damaging anything else?
Why is the sky blue?
Am I fat?

Thank you for being awesome!

Although there's not much to do to replace it, it can be quite awkward opening up the muffler enough to insert the new gasket. This can require being inventive with tools, or having an exhaust expander to hand. Not always straight-forward.

It won't take a shop long to do this, and they'll be able to check the SAS pipe is all good (or not).


Or find a friendly MV member nearby.

Is this it?
https://www.vespatorontowest.com/parts-exhaust-gasket-gt-gts-exhaust-pipe-to-muffle.html

Or this?
https://a.co/d/8moyJHX

Either - or even this https://www.amazon.com/gp/product/B01DR2251Y which is what I use.

Watch this youngster perform the operation and then decide if you have the skills to attempt it.

https://www.youtube.com/watch?v=NBmQealrX8M

Pro Tip: Buy a few more bushings than you think you'll need.

Thanks for the video. I definitely do not have those skills.

Outside of noise is there any reason I need to hurry ? Risking any related damage?

Depends on your risk tolerance.

How important is a working rear brake and electrical harness to you?

Get it fixed. The consequences can be catastrophic.

It also looks like you may have a valve cover leak. Lots of what looks to be oil accumulated on the engine back there.

But it's nowhere near the rear brake?

My mechanic is 25 km away. Too risky?

It's not near the rear brake, but is close to the hydraulic line that operates the brake. 25km should be okay, that's across town in some cities.

Can't I just tape it up temporarily to buy time?

Not on a GT200 - the rear brake line is on the left side, not the right.

Insulations on electrical wires are at high risk though.

Maybe not as often, but I think the GT model is still at risk of brake line blowout. For example:
https://modernvespa.com/forum/post1600361#1600361

Nancy80, it sounds like you might be in Toronto? I'm out of town for a few weeks, but could potentially help you out early Sept if you're still stuck then.

In which case they must have re-routed the rear brake line from the earlier models to a completely different location. Why they'd want to go from left (at the bars) to the right (by the exhaust) and back to the left (to the caliper) is beyond me...

No I am not but thank you very much!

Reading that thread I read aluminum foil. Can I wrap the muffler part with foil with duct tape as a temporary stopgap from harming the brake line (till repair later this week)?

No - it gets too hot. You can try tightening the clamp up a bit.