Nothing major has happened to the bike.
I got a float stuck on the carb, cause there was a grain of dirt in the carb.
If you keep the bike maintained, it will run for ever.
The CB750 is awesome. My bike is totally custom, it is one of a kind, there's nothing like it.
I got the stock frame, but I cut the back half off and welded my own single seat bar on.
I've got the stock motor, the stock forks, stock rear shocks, GSXR 1000 rear and front wheels, GSXR 6 piston front calliper, and 4 piston rear calliper.
Besides the custom work I have done, the CB750 is an awesome bike!!!
Do you have any pictures of your modifications? I also have a '93 Nighthawk, and have been brainstorming as to what direction I want to go with future mods.