Dealer Comments When the next step up is into the 50cc class, there is no better option than the most powerful 50cc out there. For 2024, the KTM 50 SX is built around an advanced steel frame, housing a powerful engine, a 35mm WP XACT AER fork, a WP XACT monoshock, and an advanced hydraulic Formula brake system. Simply put - it's the most advanced and READY TO RACE 50 cc mini-crosser available to your little racer.