The 2004 KTM 450SX started out as a single-overhead-camshaft engine with a kickstarter but by 2007 had been that had been transformed into a DOHC, electric-start motor.
Used bike review: 2004-07 KTM 450SX
Both engines had a four-speed gearbox with a hydraulically-operated multi-plate wet clutch and Brembo brakes front and rear.
Both models had WP suspension front and rear but by 2007 the front fork had been changed from open-chamber to closed-chamber. Both engines are liquid cooled and use an pressurised lubrication system.
The earlier models ran a compression ratio of 12.0:1 but the 2007 had the ratio increased to 12.5:1. Both motors ran four valves but the bore and stroke on the ’04 model was 95mm x 63.4mm compared to the 2007 model’s more oversquare 97mm x 68mm.
Both engines used a flat-slide Keihin carburettor and Kokusan digital CDI. The air filter became removable from the side of the airbox on the ’07 model while the earlier models needed the seat to be removed. Both motors were powerhouses but the ’07 had a much harder, more aggressive punch that could pull a tractor from mud.
Both models used a chrome molybdenum steel frame. The chassis on the ’04 model was silver but the ’07 model went black. The ’04 held a maximum of seven litres of unleaded in the fuel tank but the ’07 model had the capacity increased to eight litres.
The ’04 model’s dry weight was 104.9kg, 900g heavier than the ’07. The ’04 model was longer than the ’07, being 1481mm long and the ’07 being 1475mm.
Both models had a ground clearance of 380mm and a 925mm seat height. Both models had a 21-inch front wheel and a 19-inch rear.
Both bikes were very powerful, but the ’07 was a much better package due to its upgrades. Its suspension was sweeter as well as the motor and chassis, which made it a much easier and nicer bike to ride. While it was nicer to ride it also had a stronger power hit that takes a lot to hang on to.
Market Equivalents:
• Yamaha YZ450F
• Honda CRF450R
• Kawasaki KX450F
• Suzuki RM-Z450