How Much Power Does the 2023 KTM 125 SX Make?

Dyno testing KTM’s all-new 125cc motocross bike for horsepower and torque.

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.”

2023 KTM 125 SX Dyno ChartRobert Martin

2023 KTM 125 SX Engine Specs

Engine Type: Liquid-cooled, two-stroke single-cylinder
Displacement: 125cc
Bore x Stroke: 54.0 x 54.5mm
Compression Ratio: N/A
Fuel Delivery: Electronic fuel injection w/ 44mm throttle body