The Faito Racing crankshaft jack up stroker kit will extend your cylinder stroke by 2.4mm from stock 49.5mm to 51.7mm. Heavier than the standard unit and balanced for minimal vibration. Strengthened piston conrod is included to fit the original sized pins. Best used with or if you already have a big bore cylinder kit and cams installed. Together with the faito 56mm big bore kit, this will increase your displacement to 128cc! Professional installation is highly recommended for this item!