I have had properly warped Brembos. I checked them with a dial gauge.
I replaced them with Arashi discs for less than half the price of pretty much anything else. They have been brilliant.
They can tell a warped disc by the oscillations of the needle on the MOT brake-o-meter. Although it is possible for a slightly warped disc to operate smoothly if it is a floating type.
If a bike is left wet and stationary for a while, the moisture trapped by the pads, can form patches of very slight corrosion, even on stainless discs.
As these patches run through the pads they can cause a feeling (and effect) just like warped discs. After the pads have shined the discs up a bit, the patches will be practically invisible, but still causing the warp effect.
I have found that the best cure for this is to wind the old girl up to a healthy lick, and brake quite hard, but smoothly and for as long as possible at a steady pressure.
Don't come squealing to a halt, but let the pressure off gently whilst still rolling.
One good pull from an unquotable speed should do the trick. Repeat as necessary..
