To bleed your brakes you will need:
Bleeding the brakes:
Remove the reservoir cap and take out the rubber diaphragm that is normally fitted inside. Top up the reservoir to the maximum level and refit the diaphragm and the cap.
Remove the rubber dust cap from the bleed nipple on the brake caliper or wheel cylinder and squeeze the hose onto the nipple.
Pour between one and two inches of brake fluid into your jar and drop the end of the hose into it. This will prevent any air being sucked up into the brake system when the bleed nipple is opened.
You’ll then need to either squeeze the brake lever or depress the brake pedal hard, (depending on whether you’re doing the front or the back), and whilst maintaining the pressure, open the bleed nipple half a turn.
As the lever or pedal completes it’s travel a small amount of fluid will be released into the jar and you should see air bubbles escaping from the bottom of the hose.
The bleed nipple must then be tightened just as the lever or pedal reaches its stop.
Repeat this process -applying pressure, opening the bleed nipple, letting the lever/pedal complete its travel, tightening the bleed nipple, and releasing the lever/pedal.
Do not let the reservoir run dry of brake fluid.
This process must be repeated until brake fluid being spent into the jar is free of any air bubbles. You should notice a firmer feel to the lever/pedal when the bleed nipple is tightened.
You have to repeat this procedure for each caliper or wheel cylinder so if you’re doing the front you’ll have to bleed the calipers on either side of the forks and obviously each wheel cylinder per axle side.
Re-check the brake reservoir and top up if necessary -making sure not to overfill as when you come to replace the diaphragm and cap it might overflow -and brake fluid will eat it’s way through your paintwork very, very quickly.
You’ve now finished bleeding your brakes.
Changing the brake fluid:
The water in the system will then heat up under braking and can form vapour locks which in turn will destroy the effectiveness of the brakes.
So changing the brake fluid at regular intervals will prevent this happening.
Top up the reservoir with new clean brake fluid and continue to operate the brake lever/pedal until you see the new clean brake fluid coming out of the hose.
This should have flushed out the last of the old brake fluid.