Brake pulsing is usually the result of pad residue on the rotor which causes uneven friction on the swept area of the rotor. This residue is deposited when you hot brake to a stop and keep/retain the front brakes clamped on the hot rotors. This practice transfers some of the material in the pad to the rotor resulting in pulsing brakes (especially true for front brakes). The rear can also develop this phenomena but not as frequently. The typical fix is to sand the brake rotors to restore a fresh metal surface and remove the offending pad residue. When hot stopping, one you are nearly stopped, release the hot front brake and use the cool rear brake to hold your position. Motorcycle brake rotors should not be resurfaced. There is not enough material to allow resurfacing. New rotors are the safe way to restore reliable braking along with quality pads.