First, I'm a relative newby here, and I know many of you have more experience with these bikes than I do, but what you're describing may not be warpage. Over the years I've been subjected to the front end wobble of various vehicles, so I've tried to pay attention to any information that might help explain what causes this and how to avoid it.
The best explanation I've come across is that the pulsation is caused not by a deformation, but rather by the uneven transfer of material from the pad to the rotor. This is usually caused by one or more high speed or prolonged braking events. After the calipers, pads, and rotors get really hot, we often bring the vehicle to a complete stop and hold the brake. This effectively means the hot pad is compressed against the rotor which causes a transfer of material. From that point on, when you apply the brake, the rotor no longer has a consistent, smooth surface. What you have is a rotor that is clean in some places, but has various layers of pad material that is 'baked' onto the surface. This varies the friction against the pads and is what causes the uneven pulsation most of us refer to as a warped rotor.
So what to do? Again, I'm no expert, but the first requirement is to get a clean, even rotor surface. 'Turning' the rotors certainly is an option, but there are also surfacing wheels that can be used with a drill to clean them up somewhat and may be sufficient. Once the surface is in shape, try a different pad and most importantly, change your braking habit. Get in the habit of not coming to a complete stop right away if you can avoid it. Try to slow almost to a stop a couple of vehicle lengths before you reach the point you intend to actually stop. Allow the vehicle to slowly move forward for that last few feet, and you've given the brakes a chance to cool down by distributing the heat around the entire surface of the rotor. Once stopped, don't squeeze the brake any harder than necessary to hold the vehicle in place. Traffic conditions won't always allow you to follow this routine, but I've found it somewhat easier on the bike than in my cars because the automatic transmissions require you hold the brake, whereas the bikes don't really require any more brake pressure than what is needed to keep the brake light switch activated. I've pretty much made this gradual stopping process a matter of habit, and I've not experienced a pulsing brake pedal on any of my vehicles in many years.
Again, I claim no particular expertise, and this explanation didn't originate with me. Just trying to pass along something that seemed like a logical argument when I first read it and my experience tells me this is a better explanation for brake pulsation than 'warped' rotors.
Gary
