I replaced my brake fluid and bled the lines last night, first time I've done this and its very easy. Between my manual, reasearching old threads, looking at how to's on the net and advice from other members I learned how to do it easy. Nate helped alot by explaining the steps on how he did his. Thanks again Nate . If your fluid is dark or dirty, the lever or pedal feel spongy then consider changing it. What I did was the following.
Attach a clear tube to the bleeder on the brake caliper, and the other end of that tube in a jar I put on the floor. Pour some new brake fluid in the jar submerging the end of the tube in fluid to keep air from being sucked into that end of the tube.
Next open up the reservior and suck out some of the old fluid with a turkey baster or syringe and fill with clean fluid. With the bleeder still closed on the caliper, slowly pump the brake lever a couple of times (slowly cause some fluid could spill out of the reservior) and then keep it squeezed in a little with slight pressure. Next open your bleeder about half a turn (I used a 10 mm box wrench) and squeeze the brake lever untill it reaches its limit. Break fluid will flow through the clear tubing.
While still keeping the break lever squeezed in at its limit, close the bleeder and release the lever. Repete that process until what comes through the clear tubing is clean and bubble free fluid. Keep an eye on the fluid level in the reservior so it doesnt get to low and suck air into the line. After three or four times refilling the reservior the fluid coming through should be clean. When done bleeding the caliper/calipers top off the reservior and replace the cap Thats basicly it. Do the same for the rear brakes. With duel disks in front you can do one caliper at a time.
DO NOT relese the lever while the bleeder is open or air will be sucked into the line and you'll have to start over. Cover your bike with lots of towels or whatever because dot 3 & 4 brake fluid will damage paint and plastic. Dot 5 does not. If your careful you wont spill any. It doesnt take long and theres an improvement in the feel of my front brakes and big improvement on how the rear brakes feel. Good preventive maintenance. Like I mentioned before, this was my first time changing the fluid and it was very easy to do. I'll be doing it once a year or so.