49mm (78.7cc) Cast Iron Sport Cylinder Kit for Piaggio 4-Stroke 2-Valve Engine Powered Scooters. Kit includes cylinder, piston, rings, piston pin, cir clips, dowel pins, and gaskets. When you use this 49mm Big Bore Kit in conjunction with your stock crankshaft you will increase your total displacement to 78.7cc! The manufacturer claims 6.5bhp at 7,500RPM is possible with this kit. Fits the following models with Piaggio’s air cooled 2 valve engines: Aprilia: Scarabeo 50 (2002-09), Sport City One 50 Derbi: Atlantis 50 (2007+) Piaggio: Fly 50, Liberty 50 (2000+), Zip 50 (2000+) Vespa: ET4 50, LX50, S50 Please see our Warranty Returns Policy.*You may need to modify your engine case to accommodate the larger cylinder.