I just finished a complete flush and refill of the F/R brake systems on my motorcycle and thought I'd share some techniques.

The first thing I did, was get some of the plastic wedge shims you use to shim doors and windows etc. After removing the calipers, I pried the pads in the calipers apart as far as possible with my 4" mason chisel (way better than a screwdriver for not gouging the pads and far easier to use) and put 2 wedges in the caliper (pointy-end to big end to make sure the "shim" was flat) and wedged them together to keep the pistons fully retracted. This forces as much of the fluid as possible back up into the reservoir for the master cylinder and minimizes the fluid volume in the calipers. Then I used a medium-sized syringe (though you could use a turkey-baster with tubing) to suck as much contaminated fluid out of the master cylinder as possible taking EXTREME care NOT to expose the hole leading from the reservoir to the master cylinder (or you'll be pumping air into the system. Then I refilled the master cylinder with fresh fluid, used a clean Q-Tip to scrub the reservoir as clean as possible, then used the syringe again to clear out the reservoir. I did this another time or 2 to make sure the fluid I was now sending down the lines and into the calipers was as clean as possible. Then I simply bled the system by hand as usual. I then pulled the shims out and put the calipers on the disks, pumped the brakes to clamp down on the disks (make sure your pads are almost new), and then topped up the system. By retracting the pistons like I did (minimizing volume in the caliper) and using the syringe, I quickly and easily removed as much of the bad fluid as possible, minimized the contamination of the fresh fluid and didn't push it down the lines and into the calipers. It worked damn good, and the brakes have never felt better.

Happy wrenching!

P.S. For reference, here's what the fluid looked like (Uck! Yeah, I know, my bad for neglecting it.)........