As one of the few manufacturers that still produces full-size two-stroke dirt bikes, KTM has designed its 125 SX to fill the gap for riders transitioning from an 85cc youth motocross bike or supermini to a full-size 250 four-stroke MXer. It’s also intended for those who want a small-bore two-stroke motocross bike that is easy to work on, less expensive to maintain and repair than a four-stroke, and features many of the same components as the Austrian manufacturer’s four-stroke models such as a steel central double-cradle frame, WP Xact suspension components, Brembo brakes, and Brembo hydraulic clutch.
We have spent plenty of time aboard the KTM 125 SX over the last decade including MY09, MY12, and MY16. When the 125 SX received an all-new powerplant and chassis design in 2016, we praised its on-track performance for being lighter and easier to throw around than the prior year model. The 125 SX’s competition in the 125cc two-stroke motocross bike segment for 2020 includes the Husqvarna TC 125, Yamaha YZ125, and TM MX 125. At $7,299, the 125 SX is $100 less than the TC 125, $1,096 less than the MX 125, and $700 more than the YZ125.
KTM commonly updates its dirt bike models from year to year, and the same rings true for the 125 SX in 2020. It received updated settings and a new piston in the WP Xact fork, revised settings and a new compression adjuster on the WP Xact shock, reworked reeds, a revised kickstart intermediate gear, and new graphics. Also, the front sprocket is now fixated with a screw and diaphragm spring instead of a circlip.