2008 KTM 125SX

2008 KTM 125 SX: Refining an Already Fast Two-Stroke

The 2008 KTM 125 SX was primarily a refinement of the heavily redesigned 2007 model rather than another new generation. KTM concentrated on smoothing the power delivery and improving suspension behaviour, while retaining the lightweight chrome-molybdenum chassis, six-speed gearbox and strong 124.8 cc two-stroke engine that had made the previous model competitive.

Engine updates included a new piston with Keystone-style rings, revised intake passages, carburettor settings and a new ignition curve. The result was a smoother, more linear powerband without giving away the strong midrange and top-end performance for which KTM's 125 had become known. Fuel continued to be metered by a 39 mm Keihin PWK carburettor, and owners dealing with worn original components can compare options using the MXOwners carburettor reference.

KTM also refined the WP suspension. The 48 mm closed-cartridge fork received reduced-friction seals and revised hydraulic bottoming components, while the PDS rear shock gained more progressive damping. Front and rear travel remained 300 mm and 335 mm respectively. Owners servicing the front suspension can use the MXOwners fork oil reference when checking oil specifications and setup.

At just over 90 kg without fuel, the 2008 125 SX remained an exceptionally light motocross bike. Its combination of sharp handling, strong brakes and a broad-for-a-125 powerband made it one of the standout small-bore two-strokes of the period. KTM's continued development of machines like this also helped preserve competitive two-stroke motocross at a time when many rival manufacturers were shifting their attention almost entirely to four-strokes.