So, in my quest for a signal generator for my project where I want to put an S12 digital cluster in my KN13 Pulsar NX, I came across these:
Speedometer Sender for Isuzu Honda Pulse Generator Hall Effect Black | eBay
Speedometer Sender for Isuzu Honda Pulse Generator Hall Effect White | eBay
They are adapters for cable-driven cars which are gonna use an electronic cluster.
As you can see, they generate 16 pulses/rev, which is exactly the amount you need to make the NX1600 clusters show the correct speed.
You would need a plug to fit that, though, but maybe the vendor has them as well. Someone should order one, and see if it works. It would be a huge difference in price if you don't need to buy the actual sensor, but can just reuse the cable sensor.