170cc cast iron Polini cylinder kit for Maxi Scooter with water-cooled 125-150cc 4-stroke Yamaha engines such as Benelli Velvet; Italjet Millennium; Malaguti F12 Phantom, Madison; MBK Cityliner, Doodo, Skyliner, Thunder; Renault Kouranos, Yamaha Majesty, Maxster and Teos. The cylinder has a 63mm bore and achieves an output of 15.5bhp at 7,500RPM according to manufacturer´s claims.