My 95 FXST is a special construction, so it differs is some ways from a factory-built bike. I was looking for the rear master cylinder right next to my rear brake pedal/lever and there's nothing there! What I see is the steel pushrod from the brake lever going straight into the rubber boot. Then the brake line from the rear of the boot, goes to the brake caliper. Where would the brake fluid go in that type of set up? Is there a reservoir inside the rubber boot?

 

Special construction? Could you post some pictures or clarify?Is this an old style aftermarket brake assembly, is the reservoir down stream of the pedal. Follow the brake line and see where it goes.