The 125cc two-stroke may not be the star of the stadiums anymore, but the small-bore two-stroke still holds a special place in the hearts of the motocross community. Ultralightweight handling and fast-revving, peaky power delivery make bikes like the 2025 KTM 125 SX easy to manage, but difficult to ride fast—an excellent training tool for young riders transitioning to the full-size ranks.
KTM is one of the only major manufacturers to carry on with two-stroke development in the past 20 years. Its latest innovation on the SX line of two-stroke motocrossers is fuel injection. Using throttle body injection (TBI) fuel systems, the KTM 125 SX now features Keihin EFI and reed valve case design. No more fiddling with jets, although riders do still need to add premix to their fuel.
For 2025, the KTM 125 SX receives updates to the frame and the suspension settings, the same revisions given to the entire MY25 SX and SX-F lines. Technology such as electric start, WP Xact air fork, Brembo brake and clutch hydraulics, and switchable engine maps put the 125 SX on par with the most advanced motocross bikes available today.
The 2025 KTM 125 SX is available in orange for $8,199.
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