2004 KTM 250SX

2004 KTM 250 SX – Refining the Austrian Two-Stroke

The 2004 KTM 250 SX was an evolutionary development of the substantially updated 2003 machine rather than another complete redesign. KTM retained the successful 249 cc two-stroke engine, chrome-moly steel chassis, 48 mm WP fork and linkage-less PDS rear suspension while concentrating on refinement and making the package easier to race.

The liquid-cooled engine continued with a 66.4 x 72 mm bore and stroke and a 38 mm Keihin PWK carburettor. KTM's exhaust power-valve system broadened the delivery of an engine already known for strong 250-class performance. More than two decades later, carburettor condition can have a major effect on how one of these bikes runs, making the MXOwners carburettor information and replacement options useful when restoring a worn original PWK.

Suspension remained distinctly KTM. The 48 mm WP upside-down fork provided around 300 mm of travel, while the rear used the WP PDS shock without a conventional rising-rate linkage. PDS reduced the number of linkage bearings exposed underneath the bike, but correct spring selection and sag remained important to handling. Owners servicing the front suspension can also consult the fork oil level reference.

Brembo hydraulic disc brakes and a Magura hydraulic clutch continued to give the KTM premium equipment compared with many contemporary motocross machines. Its 21-inch front and 19-inch rear wheels followed standard full-size motocross practice, while a dry weight of roughly 101 kg kept the 250 SX light and responsive.

Today the 2004 250 SX remains a straightforward and potent early-2000s two-stroke. A fresh top end, clean power valve, correctly jetted carburettor, serviced WP suspension and regular gearbox-oil changes are far more valuable than extensive modification. Correct rear suspension and race sag setup is also worthwhile, particularly on a bike whose shock and springs may have seen more than twenty years of use.