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Yamaha WR400F 1999 Parts & Accessories

First introduced in 1998 with the pioneering WR400F, Yamaha's WR4-Stroke Series (WR400F, WR426F, and WR450F) revolutionized the modern four-stroke enduro landscape by adapting world-championship YZ motocross engine technology into high-performance off-road endurance machines. The original WR400F (1998–2000) introduced high-revving 5-valve DOHC performance to woods and desert racing, which evolved into the displacement-boosted WR426F (2001–2002) featuring revised chassis geometry and improved power delivery. In 2003, Yamaha debuted the WR450F, introducing electric start and further engine displacement increases, eventually adopting aluminum frames (2007), rearward-slanted cylinder layouts (2016), and smartphone ECU tuning to maintain its position as a world-standard open-class enduro machine.

• Engine Displacement: 399 cc (WR400F: 1998–2000), 426 cc (WR426F: 2001–2002), 449 cc (WR450F: 2003–present); liquid-cooled DOHC 4-stroke single-cylinder
• Fuel Systems: 39 mm Keihin FCR carburetor (WR400F/WR426F/early WR450F); 44 mm Mikuni Electronic Fuel Injection (EFI) on modern WR450F models
• Frame Construction: High-tensile steel double-cradle frame (WR400F/WR426F/early WR450F) transitioning to lightweight aluminum bilateral beam frame (2007–present)
• Suspension (Front): 46 mm–48 mm KYB inverted telescopic front forks providing 300 mm–310 mm (11.8 in–12.2 in) wheel travel
• Suspension (Rear): Fully adjustable KYB rear monoshock with Link Monocross linkage providing 315 mm–317 mm (12.4 in–12.5 in) wheel travel
• Brakes: Hydraulic single front disc brake (250 mm–270 mm) and hydraulic single rear disc brake (220 mm–240 mm)
• Transmission & Drivetrain: 5-speed wide-ratio manual transmission with multi-plate heavy-duty wet clutch and chain final drive
• Starting System: Kick-start only with manual compression release (WR400F/WR426F); push-button electric start with automatic decompression (WR450F 2003–present)
• Wheel Dimensions: 21-inch front (80/100-21) and 18-inch rear (110/100-18 or 120/90-18) heavy-duty spoked wheels with off-road tires
• Average Operating Weight: 113 kg–123 kg (249 lbs–271 lbs) wet weight depending on model era and equipment