How to Bleed the Front ABS Brakes on a Motorcycle

by Chris Gilliland

Anti-lock braking systems have been used in the automotive industry for decades as an added safety measure in the event of a hard emergency brake that could easily turn into a skid. However, the technology is relatively new in the motorcycle industry. As more motorcycles are being equipped with ABS brakes, motorcycle riders must learn to maintain their bike's braking system. This can make the relatively simple task of bleeding air out of the brake lines a challenge. While the basic procedure is still used, some motorcycles require an additional step to remove air from the valves that control the ABS system.


Remove the lid from the front master cylinder, located on the right handlebar, using a Phillips screwdriver or by unscrewing the lid by hand. Remove the inner diaphragm from the reservoir, then suck out the old brake fluid with a hand pump or syringe.


Refill the reservoir with DOT 3 or 4 brake fluid, as listed on the reservoir lid. Add fluid until the fluid level is aligned with the "Full" mark imprinted on the side of the reservoir.


Pull the rubber boot off of the left front brake caliper bleed nozzle, located on the top of the caliper. Slip a box-end wrench, followed by a 3-foot length of clear plastic hose, over the nozzle. Place the opposite end of the hose in a plastic bottle.


Turn the nozzle counterclockwise a quarter-turn with the wrench and pull in the brake lever to force a small amount of brake fluid and air bubbles out of the caliper and into the hose. Turn the nozzle clockwise, then slowly release the brake lever. Repeat until air bubbles are no longer released from the caliper.


Pull the plastic hose off of the left brake caliper, using a shop towel. Then place the hose on the right front brake caliper bleed nozzle. Refill the master cylinder reservoir with brake fluid. Bleed the right brake caliper, using the same method.


Access the motorcycle's fuse box and ABS control module to activate the ABS pump. Push the plastic hose over the ABS control module bleed nozzle and place the free end of the hose into a plastic bottle. Turn the nozzle counterclockwise a quarter-turn with the wrench and observe the brake fluid that is being pumped into the hose from the ABS control module. Turn the nozzle clockwise once the brake fluid is free of air bubbles.


Deactivate the ABS control module and remove the plastic hose. Wipe away any spilled brake fluid, using a shop towel.


  • check Some motorcycles, such as ABS-equipped Harley-Davidson models, will require special dealer-specific tools to activate the ABS system for air bleeding.
  • check Keep an eye on the brake fluid levels in the master cylinder fluid reservoirs. Refill the reservoirs as soon as the reservoir is less than one-third full to prevent air from entering into the brake circuit.
  • check ABS bleeding instructions, as well as a complete list of specialized tools, specific to your motorcycle can be found in a factory service manual. Contact your local motorcycle dealership to obtain a service manual.


  • close Brake fluid is a caustic solvent that can damage painted surfaces and cause severe skin and eye irritations. Cover painted body panels with a fabric drop cloth and wear protective gloves and eye wear while working on your motorcycle's ABS brake system.
  • close Take used brake fluid to your nearest motorcycle repair center or automotive parts stores for disposal.

Items you will need


About the Author

An avid motorcyclist, Chris Gilliland has immersed himself into the two-wheeled world while balancing work life and raising three daughters. When he is not managing the parts department of a local, multi-line motorcycle dealership, Gilliland can often be found riding, writing or working on his motorcycle blog, Wingman's Garage.

Photo Credits

  • photo_camera Jupiterimages/Polka Dot/Getty Images