Front brake caliper pistons do not want to retract...

I was having trouble with my front caliper when trying to change the pads. The pistons would not retract far enough into the caliper to allow the new, thicker pads to fit round the rotor. I removed the caliper and tried pushing in the pistons with my thumbs, but they wouldn't budge.  I was afraid to pump the brake lever, because I was afraid that I would end up pinching the pistons and would end up totally screwed. The original pads turned out to be not as worn as I thought, so I just re-installed the old pads, then bled the system to hopefully improve function. How can I get the pistons to retract into the caliper so new pads can be installed in the future?

Edited by uninc4life

Try loosening the top banjo bolt and see if they will start moving. If that does not work use a large flat blade crew driver and apply only small amounts of pressure to see if you can loosen them up. I suggest removing the pistons and cleaning them up. They are probably slightly corroded. Also applying a small amount of grease will help. I do this once a year on my bikes to help with corrosion.

Master cylinder may be overfilled.

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