I have had a problem with the brakes on my Sporster build and thought i would share the results with you all just in case it happens to you.
I have used the standard bmw master cylinder with the adaptor plate,after bleeding i had little to no brake pedal basically 2 inch travel before any brake pedal!
After examining the system i found that the server actuating rod is 8mm short of the master cylinder piston.
I have resolved this by making a sleeve to fit over the actuating rod and make it 8mm longer now i have a full brake pedal