KTM 125 SX / 150 SX / 150 XC Service Manual (2014)

KTM positioned the 125 SX as its full-size entry point into serious motocross, a role the model had held for years by the time the 2014 version appeared. KTM Australia’s period description called the 125 SX a springboard from junior racing toward the professional ranks, and the model’s light weight, six-speed transmission and high-revving two-stroke character made it particularly suited to riders moving up from 85 cc machinery. The 2014 bike retained the established 124.8 cm³ reed-valve engine and chromoly-steel chassis while KTM concentrated on refinement rather than a clean-sheet redesign. KTM’s official model application archive preserves separate 2014 EU and US 125 SX entries.

The 150 SX developed the same basic motocross concept with extra displacement and torque. KTM’s model records show the 150 SX appearing for 2009 after the earlier 144 SX period, and the 2014 factory specification still demonstrates how closely the two SX models were related: both used the same basic frame, WP closed-cartridge fork, linkage rear suspension, six-speed gearbox, hydraulic clutch and 19-inch rear wheel. The larger machine increased displacement to 143.6 cm³ through a 56 × 58.4 mm bore and stroke and used taller 13:48 final gearing, while the 125 retained 13:50. Motocross Action’s 2014 125 SX retrospective test describes the shared platform and the principal 125/150 engine and gearing differences.

The 150 XC took that lightweight 150-class idea into cross-country competition. Dirt Rider described the new 2010 150 XC as a 125-sized motorcycle in weight and feel but with extra power, filling a niche between small-bore motocross machinery and heavier four-strokes. By 2014 the XC had evolved into a distinct off-road specification: a 10-litre tank with reserve, 18-inch rear wheel, 13:50 final ratio and WP 4860 4CS fork with 292 mm travel. The SX machines retained 7.5-litre tanks, 19-inch rear wheels and WP 4860 MXMA CC forks with 300 mm travel. These differences made the XC a dedicated cross-country member of the same small-bore two-stroke competition platform, not simply an SX with different graphics.

The 2014 generation followed a substantial round of chassis development in 2013. KTM had reinforced the swingarm around a larger rear axle, revised the bodywork and triple clamps, and updated suspension settings. For 2014 the changes were more evolutionary. Period testing records new Boyesen reed petals on the 125, revised front-brake components, a lighter chain guide, updated seat foam and a lower-profile fuel cap, while the core engines and chassis architecture carried over. That context is important because 2014 sits near the end of this generation rather than at the beginning of a new one.

A clear generational break arrived for 2016, when KTM replaced the 125 and 150 SX with substantially new motorcycles featuring lighter, more compact engines and new frames. Cycle News described both 2016 two-strokes as complete overhauls, distinguishing them from the 2014 platform documented here. This download is specifically the 2014 factory Repair Manual for 125 SX EU/USA, 150 SX EU/USA and 150 XC USA. It contains no 125 XC coverage, so that previously assigned model has been removed. Related factory publications are grouped in the KTM 125 SX manual catalog.