The Vespa T5 was a bike that was never introduced in the USA, but has an engine which is the latest iteration of the PX125 design. It has a larger crankcase mouth opening which allows five transfers to be cast into the face. The barrel that comes on a T5 is only 55mm. Malossi has taken the bore as far as it can go and offered a 172cc kit allowing almost 50cc more. The stroke remains at 52mm. Thanks to Rob Ormsby for the pictures.