The YZ250 is a 2-stroke motocross race bike made by Yamaha. It was launched in the 1970s, and has been regularly updated since. It is slowly being phased out and replaced by its four stroke rival, the YZ450F.
The YZ250 has a 249 cc liquid-cooled two stroke reed valved engine with a YPVS exhaust valve for a wider spread of power. The engine produces a peak 46.8 horsepower (34.9 kW) at 8800 rpm and 30.6 foot-pounds force (41.5 N·m) of torque at 7500 rpm, with a 9000 rpm redline (Motocross Action Magazine).
In fact, it is still making 45.0 horsepower (33.6 kW) at 9100 rpm and 41.6 horsepower (31.0 kW) at 9600 rpm before the rev limiter kicks in.
Since its introduction in 1974, the YZ250 has had a single backbone steel frame. For the 2005 model year, however, the YZ250 has a new frame made entirely from aluminum, which brought the dry weight down to 212 pounds.
The bike has a Swingarm rear suspension system with more than a foot of travel, as well as telescopic inverted forks with 11.8 inches (300 mm) of travel. Front and rear hydraulic disc brakes round out the YZ.
The YZ250 holds many championships:
- 5 AMA National Motocross Titles
- 9 AMA National Supercross Titles
- Most recently, Chad Reed rode the YZ250 to an AMA National Supercross title in 2004.