Polini 78.8cc Big Bore Kit | Vespa Piaggio 4T 50cc Engines

Bump your Piaggio 4T 50cc scooter to 78.8cc with the Polini Big Bore Kit. Designed for 4-stroke 2-valve and 4-valve 49cc Piaggio engines, this complete kit includes a finned aluminum alloy cylinder, flat-top piston, full gasket set, and all hardware needed for the bore-up. The 11.6:1 compression ratio delivers a significant increase in mid-range and top-end power, and the included gear-up ratio (14:43) provides a 60% increase over stock (11:54) for improved top speed.

For off-road and closed-course competition use only. Not intended for use on public roads or land. Not legal for use in California on pollution-controlled vehicles. Performance upgrades are not covered under warranty.

Kit Contents

• Finned aluminum alloy cylinder (78.8cc bore)
• Flat-top piston
• Piston rings (3-ring set)
• Circlips (x2)
• Wrist pin and dowel pins
• Head gasket (green composite)
• Base gasket (black)
• Exhaust gasket
• Rubber intake manifold spacers

Features

• Increases displacement from 49cc to 78.8cc on Piaggio 4T 2-valve and 4-valve engines
• 11.6:1 compression ratio for significant mid-range and top-end power gains
• 14:43 gear-up ratio — 60% increase over stock 11:54 for improved top speed
• Complete kit: aluminum cylinder, piston, rings, circlips, wrist pin, full gasket set, and intake spacers
• Made in Italy by Polini — Polini P/N 140.0223

Specifications

• Displacement: 78.8cc
• Compression Ratio: 11.6:1
• Gear-Up Ratio: 14:43 (60% increase over stock 11:54)
• Cylinder Material: Aluminum alloy
• Polini Part Number: 140.0223
• Made in Italy

Model Fitment

• Vespa LX 50 (2006–2009) — 4-stroke 2-valve
• Vespa LX 50 (2010–2014) — 4-stroke 4-valve
• Vespa S 50 (2009–2014) — 4-stroke 4-valve
• Vespa Primavera 50 4V Carb (2015–2019)
• Vespa Sprint 50 4V Carb (2015–2019)
• Piaggio Fly 50 (4T)
• Scootcoupe P50

California Prop 65 Warning: www.p65warnings.ca.gov