Can you share any instructions on the brake teardown? do you rebuild the calipers - if so - do you reuse the rubber o-rings or replace them?
Some of the details vary- eg those old Bandit tokico's could be split (meaning the caliper can be separated into 2 halves- only had to do that once on a profoundly neglected friend's bike). The R6 calipers had a big hex recess head cover that could be removed to expose the backside of the pistons- not recommended to do that, thankfully I never had to. For the gxs, it doesn't look like any of that is possible or desirable- which is good- those intrusive measures can turn into trouble.
So this fall when I do the gsxs I will take off the calipers, pads, shields etc, front and rear. Then use compressed air to slowly push out the pistons- have to be careful to not just blow them out which can do damage. A piece of plywood or similar positioned in place of the pads can be sized to get the pistons most of the way out. Then the compressed air will get them mostly out, so they can be removed by hand. In extreme cases compressed air isn't enough, so plan b is to fill the caliper with oil and fit a grease zerk in the bleeder hole, then pump in a bit of grease to force the pistons out- PITA but it works really well. Oil is lots easier to clean out of the caliper than if you fill the whole thing with grease.
Once out, the the pistons are cleaned (brass brush and solvents, maybe a wirewheel, but no sandpaper or grinding) and seals examined, lots of times they are fine and can go back in. On neglected and/or old brakes they'll usually need replacement and lots of cleaning and scraping in their recesses in the caliper. The piston bores are inspected and cleaned with a toothbrush and solvents.
The rest of the calipers are scrubbed with solvents and brushes to clear all the brake muck etc, then reassembled. All screw-in fasteners (except the brake bleeders) get grease or other antiseize. I always wet the pistons and seals with a bit of fresh brake fluid to help things go together. If pads need replacing, I do that too. If not then I scuff them with with coarse sandpaper and swap them between calipers. Discs are sprayed with brake cleaner and also scuffed with sandpaper- this helps remove any glaze or baked-on dirt etc.
Before reinstalling and reconnecting hoses, all the fluid is drained from the master cylinders- they might need cleaning too. Anyhow once all thats done and everything is back together, then the tedium of filling and bleeding begins. Sometimes its easy sometimes not... Once the master cylinder is pumping well thru the calipers then I bleed out another reservoir full thru the caliper bleeders. A vacuum bleeder can save a lot of time, particularly if having trouble getting the master cylinder pumping.
Usually takes me a few evenings in the garage to get it done, maybe up to a week of evenings depending on how much work is needed or if waiting for parts.
The R6 brakes went quickly, about 2 evenings total after the first overhaul which took a bunch of work. The 1st time thru the R6 brakes I had a really stuck piston, I tried a piston removal tool- didn't work either- I needed the oil & grease trick with it- but compressed air worked fine after. The Bandit brakes were always a mess; seized pistons mostly, it was a fight getting some of them out- it took several evenings, or perhaps an all day weekend. Being new, I expect the gsxs brakes to go quickly.
Its desirable to have a full set of piston seals handy when you go in, save them in the parts box if not needed. Sometimes one will be smeared/twisted/damaged so you don't need the whole set at once but having it handy can save a bunch of time.
Its one of the bigger and messier jobs short of diving into the engine, but I find the quality of the braking and generally easier maintenance next time around to be well worth it. Its lots easier to do the routine on brakes that were overhauled the year before vs brakes that have been unmaintained for several years (even if fluid was changed- that won't unstick a piston).
