Have a set on my bike I use for uplifts,so not used every week but without fail every time I go to check it before an uplift some of the pistons are sticking. I manage to release them and give them a clean with brake fluid using a cotton bud,is their anything I could try to stop them sticking.

Replace the seals? Its easy enough job to do

Mine used to stick regularly, but since coating the pistons in silicone grease they have been fine for a couple of years.

Try cleaning them with silicon lube instead of brake fluid. I use a spray one every now and then on mine.
I think the muckoff brake cleaner advertises itself as lubing the seals too but I prefer to give mine a proper clean and lube once in a while.

As above, it will be crud trapped in the recess for the seals.
each time you get them moving you’ll only be sorting it short term as the crud will still remain. A full strip and clean should solve it. You could get new seals but I’ve found a good clean usually gets them back to their best. Out if interest, which M4s do you have?

Tech M4. Thanks guys

If you have the new M4 brakes then you should have the phelonic pistons which is a slippery coating to reduce this so it sounds like you have the old ones (or just have bad luck). Take the bore caps off, clean the pistons/seals with oil/lubricant and it should be fine. Try not to get brake fluid on the pads!!!

I remember hope recommending some kind of plumbers oil for the pistons, cant remember where I saw it or which kind though

edit…

found it…

[video]http://www.youtube.com/watch?v=v83YFGi5uT0[/video]

1m17ish