GT4 exhaust... particles...?

This is normal, Every carb GT4 I have seen spits hydrocarbons. Take a wet cloth and wipe off your bumper. You will find it black. You have a car with carbs. If you had a US version with your smog pumps hooked up it will diminish this but increase your engine temps significantly. I would move the bike....

 

Very normal indeed. Exhaust gasses turn to water when the exhaust cools. That water will be standing in something that is rather soothy on the inside (your exhaust). Starting the car up will blow this soothy water out onto whatever is parked behind you.

Experience tells me that anything within 10 feet of your rear bumper will get covered in black droplets. My local FChat buddies know this by now and nobody wants to park behind my car these days

Just throw a sheet or something over the Vespas, or push the car out before starting...

 

My injected car ('81) does it too. Not quite that bad but it does it never the less.

 

My GT4 would do it to and my 328 does it as well,although not as much.

 

Welcome to the world of carburetors. When I was young my dad had an old car with turned down pipes at the rear. Two large black spots in the garage from starting it up. But it smells soo good, memories from childhood. Before it warms up my Mondial provides some of that old smell. Mmmmmm, unburnt hydrocarbons

And yes, move the scooters, I believe that stuff can be corrosive, you don't want it on your paint.

 

I didn't know you could put a sidecar on a Vespa.

 

I started my Ferrari in front of the white TransAm......NOT a good idea!