Actually no they do Not swap. The ZX is unique, and alone in the Kymco world. Even the DIO vars do Not work correctly. Other vars fit but the diameters are different, and the boss length is different. Jassil, Polinni,Malossi are the only three I would recommend. I tried the Prodigy, and it is a cheap ass POS. The ramp plate self destructs, and will destroy itself in short order.
All three of the Vars I mentioned sell for about $100.00 delivered. I currently have the Jassil in one engine, and the Malossi in a second. They both work the same but the Malossi comes with a contra spring as a bonus
If you want a Polini or Malossi I can get either for 85.00 bucks shipped, and The jassil is available from Moped Hospital