<HTML>I don't know about Baretta's, but I do know about the Vespa, I have a ciao myself.
First of all, it's either a ciao or a piaggio, it can't be both because they're different Vespa models. The piaggio has rear shockbreakers, the ciao has no rear shockbreakers. The piaggio has a wider footboard and that's about it. Most of the parts of the ciao and piaggio are interchangable, that's probably why it read's both ciao and piaggio.
If it's a ciao (without rear shockbreakers) and you have a rearwheel with spokes you should replace it as soon as possible for a rearwheel with those plastic things (don't know what theire called in English) instead of spokes. My rearwheel had 5 bent spokes and 3 loose spokes all because the ciao hasn't got any rear shockbreakers.
There are two versions of the ciao and piaggio, the kind that goes about 20 Mph and the kind that goes about 30 - 35 Mph. The difference between the two are the carburettor, the slower has a 9mm, the faster has a 13mm, and the slower has a little ring inside the inletmanifold on the carter. That little ring makes the inletmanifold smaller and restricts the airflow into the engine. The last difference is the airfilterhousing, the three holes in the airfilterhousing of the slower kind are smaller. If you want to tune up the slow ped to go as fast as the faster ped you should drill out the holes in the airfilterhousing, replace the carburettor for a 13mm (costs $30 ) and remove the restrictor-ring in the inletmanifold. The ring will be hard to remove, if you use force to remove it then be sure that NO iron filings get into the engine, they'll grind away the crankshaft and destroy the cylinder. Recalibrate the carburettor if you change any of these three things, it's really easy, if the ped runs better with the choke on the carb needs a bigger jet, if the peds runs poor at full throttle (or even dies out) and the sparkplug is blackened and wet the carb needs a smaller jet, and clean the sparkplug. Turn the screw on the right side of the carb to set the idling speed, sit it as low as possible, but not that slow that the engine might stall.
I hope this is enough info for now, have fun with your ped!</HTML>