Barrel identification

[fullenglish]

Picked up a motor recently and today had a better look inside, cylinder head and piston marked polini the barrel is iron but no makers mark, it's a well ported reedvalve motor anyway the exhaust port is bridged which i can't find one image on Google of a similar barrel,,
Can anyone shed any light ?
Is it possible the bridge has been added by a tuner to protect rings or does a polini barrel come like that also with no polini stamp ?

[gpowell]

Assuming we talking 200 here.
Polini didn't come with bridged exhaust port.
Autisa did, these were Ali with iron liners.
If memory serves me right MDP made a barrel exactly the same as polini and that had a bridged port.
Both Autisa and MDP kits were discontinued along time ago.
If its not them then yes it's likely been added.
Polini didn't makes head until recently.
I'm always interested in old Vespa barrels Be interested to see some pictures.