Rear caliper pistons won't all the way in

[vRSG60]

OK so after the winter lay up I went for a ride on Saturday and the rear pads stuck on, buggered the pads.
Put new pads on tonight but the pistons would only push back all the way in independently. Push one in and the other comes out.

The only way I could get them both in so I could refit the caliper was to open the bleed nipple. Yes I did remove the reservoir cap and removed the rubber bung bit.
I had the ignition on but not the engine running.

Could it be something to do with trying to adjust the lever position on the rod?

 

[roamer]

The rod at the master cylinder can be over long , by adjusting too much to take slack out of the pedal travel, if the rod has been lengthened , re adjust it back and see if the pads push back both sides together,
my pads pushed back without bleed nipple released, front and rear,, ignition off, just verify the pads can return as this may be why the others looked overheated/sticking,
The ignition should be off when doing the wheel circuits, the abs is looking for pressure differential and may shut off the return flow and create a fault warning if switched on,
Roamer

 

[vRSG60]

Thanks Roamer.

 

[roamer]

To be fair the rear brake does appear to travel an inch or so when static, adjusting the rod as you have can hold the return valve closed, you should be able to feel a slight mechanical clearance at the brake pedal of 2 to 3 mm,
so backing it off and confirming a clearance , and making sure both rear pads push all the way back ignition off at least gives you peace of mind,
Roamer