As the marque's entry-level sportsbike, the motorcycle has undergone few changes throughout its quarter-century lifetime, having received only two substantial redesigns.
The first generation was produced between 1983 and 1984, and known by the production number EX250-C. It was sold as the GPZ-250. Sold only in its home market of Japan, this earliest, belt-driven version was first produced in 1983, and shares no commonality with later generations.The bike has 35mm fork tubes.
Produced between 1986 and 1987 was the EX250-E. This model was sold as the Ninja 250R in Canada and the U.S. between 1986 and 1987. It was known as the GPZ-250R elsewhere. When originally introduced, it was more costly than the Honda Rebel, and reviewers complained that while the 14,000 rpm redline was nice, the engine was slow to rev.
For the 1988 model year, there were both cosmetic changes and changes in engine tuning. While the bore and stroke, and other major engine components, were unchanged, minor tuning adjustments were made. The carburetor diameters were reduced 2 mm to 30 mm (1.2 in), the cylinder compression ratio was increased from 12.0:1 to 12.4:1, ignition timing advance was increased, and the rear sprocket was increased by three teeth to 45.Reviewers reported that this made the engine more free-revving, reaching the high 14,000 redline more quickly, and the tested top speed increased by a few miles per hour.The new, more fully enclosed bodywork was complimented for being stylish, at the time, and easily mistaken for the larger Ninja 750.
The third generation of production of the Ninja 250 encompassed three models:
- EX250-F - The most widespread EX250 variant, the E model was completely revamped and sold as the F model between 1988 and 2007 in the United States. Canada received the model between 1988 and 1999, and it was available elsewhere as the GPX-250R as early as 1987.
- EX250-G - Sold only in its home market of Japan, this version was known as the GPX-250R-II. It featured dual front brakes and a wider wheel and tire (110/80-16). All other parts were identical to the -F model. It was sold after 1988.
- EX250-H - This model came to Canada as the Ninja 250R between 2000 and 2002, after which it received a new name: ZZR-250, in line with the -H model's name elsewhere in the world, where it had existed since 1992. This motorcycle has few parts in common with the -F model, though it shares the same engine, albeit with different casings. It sports a lateral aluminum frame, a different fairing (designed to make it look sportier), larger 17-inch wheels, an adjustable rear shock absorber. adjustable brake and clutch levers, a smaller drive sprocket, computer-controlled timing advance, and a revised electrical system.
In 2008, Kawasaki gave the EX250 its most thorough modernization in many years. The EX250-J model is known as the Ninja 250R worldwide, regardless of market.
Parts from the third generation are still found on the -J, but its redesigned exterior panels bring the Ninja's appearance out of the 1990s and into line with late-2000s sportbikes. The engine and drivetrain retain 30% of the -F model's parts, according to Kawasaki.The engine's compression and maximum torque have been lowered to provide better midrange performance. The redesign of the engine resulted in improvements in engine response at low engine speeds, and making the bike smoother and "much easier to ride." Though the previous generation Ninja 250 had a peak power advantage of 1 to 5 hp (0.75 to 3.7 kW), the new version's 20 or 30 percent increase in mid-range power allows the bike to pull from 3,000 rpm where previously it had to be revved to 4,000 rpm.The U.S. -J model uses dual carburetors like the -F model, but the European, Brazilian and Thai models have fuel injection. The wheels were increased in size to 17 inches, the front suspension was improved, and the brake rotoswere replaced with a larger petal shape. On the carbureted version, a fuel gauge was added in place of the temperature gauge. With the additional and redesigned equipment, the EX250-J suffered a 10 kg (22 lb) increase in wet weight over its predecessors.
With the arrival of the EX250-J, manufacturing continues to be located in Thailand.
The 2013 receives update for exterior which resembles the design of the Ninja ZX10R. The wheels are wider, with a retuned engine and exhaust. There is also an optional ABS. In some regions, the model was replaced by the Ninja 300.