
TOP PERFORMANCE Bir Bore Cylinder Kit (manufacturer ref. 9919250) — designed for Minarelli engines series AM (AM6/AM345/AM6 EU1). Built for competitive use, this kit is aimed at urban riders and roadsters who want a targeted and reliable engine preparation. The flow in the transfer ports has been reworked compared to the previous version: the number of ports has been reduced from 7 to 5 with increased flow, which has improved the power curve across the entire RPM range.
Common compatibilities: Aprilia, Betamotor, CH, HM, HRD, Husqvarna, Motorhispania, Malaguti, MBK, Peugeot, Rieju, and Yamaha equipped with Minarelli AM engines. Particularly suitable for 50 cm3 models such as VENT DERAPAGE 50 RR, SHERCO SM 50 RS, and RIEJU MRT 50 SM TROPHY. Proper installation and adjustments are essential to fully utilize the kit.