POLINI 75cc CYLINDER KIT Ø 47 mm - VESPA 50 - APE 50 - RACING VERSION

This Polini RACING cast iron cylinder kit Ø 47 mm with 75 cc displacement is a high-performance solution designed for riders looking to significantly improve the performance of the original engine on Vespa 50 and Ape 50, while maintaining long-term reliability and robustness. It is compatible with Vespa 50 N, 50 L (Lusso), 50 R (Rinnovata), 50 Special, 50 Revival, 50 PK, 50 PK S, 50 PK XL and Ape 50.

The RACING version clearly stands out from the standard cylinder thanks to optimized transfer ports, engineered to deliver sharper throttle response and improved engine performance. Output reaches approximately 8 HP, making the engine more lively and enjoyable, especially in sporty riding conditions.

The cylinder can be installed without replacing the original 43 mm stroke crankshaft, allowing for straightforward and accessible installation. The kit is supplied complete with cylinder head and gaskets, ready for assembly, with no need for specific machining on the crankcases.

The cast iron construction and Polini machining ensure high mechanical strength, good low- and mid-range torque and controlled fuel consumption, providing reliable and consistent performance even under demanding use. For those seeking to fully exploit the potential of the cylinder kit, a racing crankshaft can be installed, although the original crankshaft remains suitable.

Below are baseline carburetion settings, intended as a starting point for tuning and to be adjusted according to engine configuration, exhaust system and environmental conditions:

SHB 16.16: main jet 66–68
SHB 19.19: main jet 80–82
PHBL 24: main jet 72–76 – idle jet 50 – atomizer AQ264 – needle D22 – slide 40 – starter jet 60
PHBL 24 reed-valve: main jet 100–102 – idle jet 64 – atomizer AQ264 – needle D22 – slide 40 – starter jet 60

For correct operation, the following spark plugs are recommended: Champion L78C, NGK B8HS, Bosch W3AC, Denso Iridium IWF27, with ignition timing set to 17°.

Further performance improvements can be achieved by fitting a larger carburetor, variable-advance electronic ignition, longer gear ratios, reinforced clutch and a dedicated exhaust system, depending on the intended use.

For any information or assistance in choosing the most suitable configuration, the Emporio dello Scooter customer service is always available.

Product intended for racing and sporting use only. Not homologated for use on public roads.