The rear brake on my 89 was seized solid, and I decided to pick up a whole new rear brake system on ebay for off an 05. The only problem is that its not grabbing the disc. There's a good 1/16" gap between the pads and the rotor. No amount of pumping moves it, there isn't any resistance either. There's plenty of fluid in the resevour. I'm thinking air in the line? All my previous bikes were cable actuated drums so this is new to me.
did you bleed the line after you put new fluid in it? If not you have air in the line. Look up how to bleed brakes in search and you should be good from there.
Alex