KTM had a big year in 2023. Not only did the Austrian manufacturer give its entire full-size motocross and cross-country lineups a completely new chassis, shock, and updated fork, it also granted each bike with model-specific engine updates. For the two-strokes, this meant the addition of throttle body injection (TBI) and electronic power valves.
With the trio of full-size motocross models (the 125 SX, 250 SX, and 300 SX) leaving carburetors and jets behind, many were curious how the new premix-burning machines would run on the track. Taking performance testing one step further, we ran the smallest displacement of the three on our in-house Dynojet 250i rear-wheel dynamometer before ripping it on the course. With a Dunlop D404 street tire on its rear wheel, the 125 SX spun 30.9 hp at 10,800 rpm and 15.3 lb.-ft. of torque at 10,700 rpm. In addition to admirable peak figures for such a small mill, track testing confirmed the screaming orange machine also delivers impressive bottom-end for an engine of its displacement.
“I was pleasantly surprised with the 125 SX’s low-end power, made only more impressive by its quick throttle response,” test rider Michael Wicker said. “This is still a two-stroke, so it will bog if rpm drops too low or the wrong gear is selected, but happily sings so long as the clutch is feathered properly.”
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Related: 2023 KTM 300 SX First Ride Review
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