Larry Zimmer wrote:Mike,
From everything you said, I have to go with Goss. Pull the caliper down; and, decontaminate it. Replace the seals. Even though the pistons seem to push back easily, the seals don't exert very much force. Any bit of corrosion and/or contaminate along with old seals will be enough to bind.
I second Larry's stab at it.
The seals in the caliper are square shouldered, the reason for this is to allow the caliper piston to roll back away from the rotor after the pressure is released from the M/C, the seal rolls toward the rotor while under pressure and away from the rotor when the pressure is released. If the seals are worn or deposits have built up in the groove that the seals set in it can affect the roll back of the piston and cause drag.