How to Bleed Bike Brakes

When a motorcycle's brake fluid gets dark, it is a sign that dirt has accumulated in the fluid. The fluid needs to be bled and replaced with fresh brake fluid. It is important to bleed brakes because if the brake system absorbs water, the boiling point of the fluid is lowered. In an emergency, the system could fail.

Things You'll Need

• Bike manual (if available) Empty reusable bottle Plastic tubing with diameter to fit syringe valve and mouth of catch container Syringe Rags and paper towels Spanner Screwdriver Brake Fluid Open-end wrench

Instructions

1. Attach the plastic tubing to the break caliper bleed valve. Remove the cap and push the tubing into the nipple. Pour about one inch of fresh brake fluid into the empty bottle or catch container. Push the other end of the tubing through the syringe. Place another length of tubing at the end of syringe and place the other end into the catch container.

2. Put a rag under the reservoir to prevent spilling. Unscrew the reservoir cap. Remove the diaphragm. Lay the cap and diaphragm in a clean and handy location. Empty the reservoir by pressing the brake lever to pump out liquid. Clean the reservoir by mopping it up with rags or paper towels. Fill with fresh liquid, taking care not to spill, and then replace the reservoir's rubber diaphragm. Squeeze the lever periodically to check whether the liquid shoots up.

3. Sharply press the brake lever several times to get rid of air bubbles from the reservoir. Tap all reservoir junctions to get rid of any small air bubbles with a spanner (lightly tapping the junctions is sufficient).

4. Open the bleeder valve on the caliper while keeping pressure on the brake with your other hand. Place the plastic piping in the container of fresh brake fluid. Use a squeeze/open/close/release motion until the reservoir is full of liquid.

5. When the brake feels firm and ready to use, tighten the bleed nipple to the torque specified in the user manual. Replace calipers, diaphragm and cap using the spanner. Use rags and paper towels to clean all spilled brake fluid from the floor and from other parts of the bike.

Tips & Warnings

• If the brake has a spongy feeling after bleeding, you will have to reverse the bleed using the piping, syringe and catch container, and fill the reservoir again Spray CRC on the screws to make them easier to turn.

• Brake fluid is corrosive and can damage metal parts and paint. Make sure all spilled liquid is wiped off.