Polini crankcases have been redesigned for Vespa PX and they are available in two versions: PX 125/150 and PX200 E.
A concentrated mix of technical innovation and craftsmanship, designed to offer maximum performance while ensuring compatibility with original components and the highest structural reliability.

Absolute Compatibility – Polini engine crankcases are fully compatible with all original parts.

Main Technical Features

Revolutionary Fuel system – The transition from the traditional rotary valve system to a flat reed valve system allows for:
• Elimination of carburetion issues related to the sealing of the original valve
• Improved engine delivery and overall performance
• The installation of a racing reed valve pack with a 28/30 mm carburetor (Alternatively to the flat reed, a racing reed valve pack with a peak design, without a mixer, is available, along with a dedicated intake manifold for 28/30 carburetors.)

Advanced technical details
• Modification of the assembly to prevent the clutch side oil seal from coming off
• Ground steel flanges for bearing support on the clutch side
• Enlarged ignition side bearing (25x52x15) for better smoothness and durability
• M8 hexagonal screws for a more rigid assembly, replacing the traditional M7 through bolts
• Reinforced shock absorber mounts and cylinder base
• Possibility to install the electric start
• Relocated gearbox oil filler cap to increase lubrication capacity

Mechanical and structural innovations
• Crankcases are numbered and paired during machining, ensuring:
o Perfect alignment of bearings
o Maximum flatness of the mating surfaces
• Optimized fluid dynamics through CFD simulations (finite volumes) on transfers and pump cases, for superior performance
• Completely redesigned swingarm geometry with:
o FEM analysis for structural reinforcement
o Added ribs and internal overmetal to accommodate larger wheels
o Reinforced gearbox area around the wheel spindle

Material Quality – Polini crankcases are made from light aluminum alloy Al Si10 Mg T6, cast in shell molds, and treated thermally to ensure:
• Maximum mechanical strength
• Thermal stability
• Long-lasting durability The elimination of the central gasket and the increase of the mating surface between the halves-cases also ensure better sealing and stability, even under high thermal expansion.

Ready for performance – Polini crankcases represent the perfect balance between technical innovation and respect for the Vespa tradition. Designed to support both street and racing configurations, they are ideal for those seeking maximum performance without compromise.

100% Made in Italy