POLINI 85 cc CYLINDER KIT - VESPA 50 - APE 50

This Polini cast iron cylinder kit Ø 50 mm with 85 cc displacement is a reliable and high-performance solution designed to improve the performance of the original engine on Vespa 50 and Ape 50, while maintaining strength and long-term durability. 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.

Compared to the standard cylinder, this kit features revised transfer ports, engineered to provide improved throttle response and increased performance, delivering approximately 7.5 HP. The result is a more responsive and enjoyable riding experience, while maintaining excellent reliability for everyday use.

The cylinder can be installed without replacing the original 43 mm stroke crankshaft, making installation simple and accessible. The kit is supplied complete with cylinder head and gaskets, ready for installation, 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, guaranteeing consistent and reliable performance across all operating ranges. For further performance improvements, a racing crankshaft can be fitted, 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 proper operation, the following spark plugs are recommended: Champion L78C, NGK B8HS, Bosch W3AC, Denso Iridium IWF27, with ignition timing set to 17°.

Additional performance gains can be achieved by fitting a larger carburetor, variable-advance electronic ignition, longer gear ratios, reinforced clutch and a suitable 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.