i have a 1996 Kawasaki 750 zxi jet ski ,works great but the battery does not charge, any ideas ? Thanks in advance

 

Tell us more; battery doesn't charge when it's running, or when it's on a charger?

 

Rectifier module in the e-box, or bad stator windings. You will need some test meters, etc, to measure voltages and resistance. (assuming it fails to charge while running).
A bad battery itself would explain the problem also, whether trying to charge via engine, or via 120 volt battery charger. Jetski's are hard on batteries due to wave-pounding, etc. AGM's are the best.