Help What the difference between the A, B, C and D models?

Okay so pretty much there is no English service manual that I'm aware of for anything post the A model.

However I have heard of a lot of dudes using the A models manual for engine maintenance and I'm pretty sure that appart from the cosmetics (fairings, lights etc) and power changes post 1993 that the only differences between models are: bore and stroke of pistons, cdi and potentially related components (pickup etc), jet sizing may differ, I think the carby size and or throats of the intake might differ also.
I have also read that the suspension is better in the c model but there are no sources to verify it as fact.

It is common for eBay to list models separately even if it's the same item just for the sake of it showing up in searches and reassuring the customer it's correct for their model.

In relation to your specific problem the cam chains are the same and the A service manual should provide any needed infomation.

 

the a and b are the same engine the c and d are the same engine.

 

from Wikipedia

The Kawasaki ZX-2R (also ZXR 250, ZXRR) is a 249 cc (15.2 cu in) inline four four-stroke sport motorcycle made by Kawasaki. It was introduced in 1988, with a minor update for the 1990 model year, and a considerable redesign for 1991, after which the ZXR250 received only colour scheme changes until production ceased in 1999. Like the Honda CBR250, Yamaha FZR250RR and Suzuki GSX-R250, the ZXR250 is noted for advanced, almost excessive, engineering and design with features such as inverted forks, 18 inch rear wheel and a 19,000 rpm redline.

Ninja ZXR-250 models

• ZX-250A: Sold from 1988 to 1991.
• ZX-250C: Sold from 1991 to 2004 1991-1998 in Japan 1997-2004 in Malaysia (these models were only produced in a silver and black color scheme). Changes in bodywork and front suspension 1994 models and after restricted to 40HP and reduced weight (141 kg vs 144 kg). This bike was unofficially re branded as the ZX-2R or ZXRR in Australia by importers.

The factory Kawasaki catalogue claims engine output is 45 metric horsepower (33 kW), and a restriction of 40 horsepower (30 kW) was imposed after a change in Japanese law in 1993. A SP (sports production) model known as the ZXR-250R was also available in 1990-1993 in both B and D models. The R version has larger CVK D32 (32mm)carburettors, taller 1st to 3rd gears than a regular ZXR250, different CDI as well as some other small changes. Some models also had a single seat cowl. The A and B ZXR250 models can be identified by a twin headlight arrangement which the latter C and D models featured a single headlight with twin bulbs.

Similar machines
All four of the major Japanese motorcycle manufacturers produced a sporty, high-revving, 4-cylinder, 4-stroke 250cc motorcycle capable of producing up to 45 hp (34 kW). They are the Honda CBR250RR, Kawasaki Ninja ZX-2R, Suzuki GSX-R250 and the Yamaha FZR250. With limited exceptions, these bikes were generally only officially available in Japan. However they (particularly the CBR250 and ZXR250) were available in the rest of the world as grey market imports.

 

I believe they are the same , check the part list for part numbers