Malossi T5 172
Vespa T5 - Malossi 172
Malossi's installation instructions (above) are pretty goofy but a good place to start. Here are the basic specs:
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.
The piston and barrel transfers are all significantly different from the original Vespa item.
Below is a shot of how different the crankcase openings in the motor are from a standard PX125.