Although the Vespa GTS is a fantastic long distance mile-munching scooter it still has the odd weak spot. The brittle mesh exhaust gasket is one of them.
The gasket sits between the header pipe and connecting pipe on the bulky standard exhaust. It’s made from a wire mesh and is quite delicate so it should be replaced every time the exhaust is removed but it can also fail even if the pipe has never been touched, even on relatively low mileage scooters. When it fails the exhaust starts to blow and on a few occasions (particularly on the early GTS 250) the escaping hot gasses have been known to melt the rear brake line. It’s a good idea to keep a spare one in your glovebox, just in case it goes miles from home, or away from your nearest dealer.
Luckily it’s not really rocket science to replace the gasket, it’s more of an annoying irritation and it shouldn’t take more than about 20 minutes to do the job, although it is a good idea to paint the mild steel exhaust at the same time.
First things first, remove the silencer. Depending on the age of the machine you’ll need to undo either the three retaining Torx bolts, or on earlier models the allen bolts. Also loosen the exhaust clamp at the bottom of the header pipe. Then remove the exhaust.
The gasket itself sits inside the top end of the exhaust; you should be able to see what looks like wire wool. If yours has totally burnt away it’ll be an empty space, otherwise just use a flathead screwdriver to pull the old gasket out.
Always use a new genuine Piaggio exhaust gasket, they cost around £17. Another option is to use an aftermarket aluminium ‘Fit and forget’ gasket. They’re available from places like eBay, although we can’t vouch for how good they are and some will need fettling to fit.
The clamp end of your exhaust will need opening slightly to fit the new gasket, Piaggio do an expanding tool but if you’re doing this job yourself you can make do by putting a large socket down the exhaust then prising the clamp open using a screwdriver. Just prise the ends apart wide enough to allow the gasket to slide in.
The gasket goes in mesh end first, you can carefully knock it into place using a socket of the correct size, it’s worth spraying the inside of the pipe with a bit of WD-40 to help ease things along. Don’t force the gasket too hard though because it is quite easy to damage. Once in place it should sit flush to the end of the exhaust.
With winter just around the corner it’s a good idea to give the exhaust a quick clean up whilst it’s off, remove the chrome heatshield and use a wire brush to remove any loose paint and rust from the exhaust. Then clean it down using white spirits. This exhaust is off a brand new GTS 300 and has only been used for three months; they don’t take long to rust.
Use high temperature paint and either spray or brush paint the exhaust, give it at least a couple of generous coats and allow it to dry.
Once dry, refit the heatshield then put the exhaust back on, you may need to open the clamp a bit further than usual to allow it to slide over the widened end of the exhaust. Copper grease the retaining bolts and clamp to prevent them seizing up. Hopefully your exhaust will look and sound much better once it’s done.
You might also be interested in Andy Gillard's blog on Tubeless Vespa Wheels.