in portugal we run in trofeu vespa with polini hp 75 its an excelente cilinder i eleborate 2 vespas to run in trofeu , all that vespa have the same cilinder and have diferente configurations the secret is the gear box 64/20 does not exist in shopp but i have one and i win in 2 years the championiship
polini hp worked
mazzuchelii cranck
zirri modifed
zirri 4th gear
and 64/20
you can see photos in et3.it
you tube Vespa PK75 de Troféu