By bille6: .... So the red tach indicator still lights when the brake is used.
Assuming you mean the Stop Lamp. I believe that's normal >> my 1981 KZ650-CSR has that feature. The Stop Lamp lets you know the brake light is working. On my bike if the Stop Lamp flashes without applying the brakes, that means there's a problem with the brake light circuit, which could be as simple as a burned out brake light bulb.
1981 KZ650-CSR. Competition, Sports & Road.