Yamaha YZ250
 | |
| Manufacturer | Yamaha |
|---|---|
| Production | 1974- |
| Successor | Yamaha YZ450F |
| Class | Motocross |
| Engine | 250 cc single-cylinder, water-cooled, two-stroke, case reed |
| Power | 48.8 hp[1] |
| Torque | 32 ft·lbf[1] |
| Transmission | 5-speed |
| Suspension | Monoshock, 12.8 inches travel |
| Brakes | double disc |
| Tires | Front: 80/100-21-51M ; Rear: 110/90-19-62M |
| Wheelbase | 57.8 inches |
| Dimensions |
L: 85 inches W: 32.5 inches H: 51.2 inches |
| Seat height | 39.1 inches |
| Weight |
212 lb (96 kg) (dry) |
| Fuel capacity | 2.1 US gallons |
| Related | Yamaha YZ450F |
The Yamaha YZ250 is a two-stroke motocross race bike made by Yamaha. It was launched in 1974 and has been regularly updated since. It is one of the only two-stroke bikes of this displacement to still be in production and release every year. For the Yz250 the top speed is 75mph.
Engine
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 48.8 horsepower (36.4 kW) at 8,800 rpm and 30.6 foot-pounds force (41.5 N·m) of torque at 7,500 rpm, with a 9,000 rpm redline (Motocross Action Magazine).
From 1974 through 1982 the engine sported a 70 mm bore and a 64 mm stroke to produce a displacement of 250 cc. In 1983, the bore was reduced to 68 mm and the stroke was increased to 68 mm producing a displacement of 247 cc. In 1999, the bore was further reduced to 66.4 mm and the stroke lengthened to 72 mm producing a displacement of 249 cc. The longer stroke engine resulted in a lower redline, slightly less top end power and greatly improved torque at lower RPM. 65 hp
Chassis
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 lb (96 kg), and more recently in 2010, to 211 lb. 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.[2] Front and rear hydraulic disc brakes round out the YZ.
Championships
The YZ250 holds many championships:
- 5 AMA National Motocross Titles.[3]
- 9 AMA National Supercross Titles[3]
- Most recently, Chad Reed rode the YZ250 to an AMA National Supercross title in 2004.[4]
- 6-time AMA National Offroad Championships under the hands of Jason Raines. [5]
- In 2014 Lewis Gregory rode the GL12 Racing YZ250 Yamaha to third in the newly formed EMX300 Championship. Winning the round at the Spanish GP on the way.
See also
References
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Wikimedia Commons has media related to Yamaha YZ. |