How to Service Your Brakes
The way to tell if your bike is in need of this is to just squeeze the brake handle. If it touches or comes close to the throttle grip, your calipers need serviced. What you’re going to need to do this job is some brake clean and some sort of lube like Tool Box Buddy or WD-40 and a pry bar.
Remove your calipers from the bike and pump the brake handle. As you can see, just two of the four pistons in the caliper are actually working okay. The other two are sticking.
Now what you need to do is clean the caliper pistons, spray some brake clean on them and blow dry with compressed air. You might need to do this a few times depending on how dirty your calipers are.
Now that your caliper pistons are clean, spray some lube on them. Then take your pry bar and insert it in between your brake pads and pry the pistons back into their bores. Now pump your brake handle and take notice of how the pistons come out of the caliper. What you are after is that all of the pistons all come out equally and at the same time. You’re going to have to do this a few times to get them to come out smoothly.
This is what you’re after: all pistons equally extended. This should take five to ten pumps of the brake handle. Reinstall your brake and torque the caliper bolts to spec., normally 35 ft. lbs.
Pump your brake handle till you have a nice solid feel. Notice how far away the handle is from the throttle grip. This is how your brake handle should look and feel. Now you’re ready to take your bike for a test ride. Be careful and give yourself enough time to adjust to the newly serviced brakes. This tip can be applied to anything that has brake calipers, even your old shop truck.