The first sport ATVs launched by KTM last year impressed more than a few people. The KTM 450 XC and 525 XC really shook things up thanks to a slew of high-end technical specifications and a bad-boy look. Only one year after the introduction of its first sport ATVs, the Austrian manufacturer is offering up two even sportier models. Meet the SX versions, race-ready ATVs designed for the track.

The body is decked out in more aggressive graphics.

Two engines, one chassis
KTM is offering a choice of two engines for its SX chassis, 449- and 477-cc one-cylinder mills. But why the 505 SX moniker if the engine's displacement is smaller? We believe it's nothing other than a marketing ploy. According to the engineers, however, the new 505 SX offers acceleration and throttle responses on par with 500-cc and up ATVs, which somewhat explains the machine's name. Apart from the displacement and different ignition and carburetor settings, the engines are identical.

They represent the latest innovations in technology and efficiency and are very different from the versions powering KTM's XC models and the Polaris Outlaw. This new DOHC, four-valve powerplant features a 12.5:1 compression ratio. It's fuelled by a 41-mm, flat slide Keihin FCR-MX carburetor. Its ultra-high-tech CDI ignition system has two adjustable modes: smooth and linear power band or very intense. Simply unplugging a connection on the CDI electronic box allows you to get a user-friendly power band when needed.

Original materials
As opposed to its competitors, who increasingly use aluminum in their chassis design, KTM makes it a point to maintain its conventional 4130 chromoly steel alloy tubular frame. Because it uses less material, it is as light as an aluminum chassis and has the benefit of being slightly less stiff; allowing for some damping of engine vibrations while offering some flexibility at the right time.

The beast has inherited height-adjustable, aluminum Magura handlebars.