How to Bleed the Brakes on a 1991 Kawasaki EX500A

Shop parts for a 1991 Kawasaki EX500A Motorcycle.

What the EX500A Has and Why It Matters

The 1991 Kawasaki EX500A uses hydraulic disc brakes at both ends, so the front lever and the rear pedal each operate a fluid-filled circuit. This bike is not equipped with ABS, and it does not use a linked or combined braking system. That keeps the job conventional: you are refreshing fluid and removing air from the front circuit and the rear circuit as separate tasks. The rear brake is hydraulic, not a mechanical drum, so it is bled rather than adjusted. Before you begin, check the master cylinder reservoir cap for the fluid type specified for this motorcycle, and use only fresh fluid from a sealed container.

When a Bleed Is Due

A spongy lever or pedal is the classic sign that air is in the system, but it is not the only reason to bleed. A lever that pulls closer to the grip than it used to, a pedal that feels soft or inconsistent, dark or cloudy fluid in the reservoir, or any recent work that opened the hydraulic system—new lines, caliper service, or master cylinder work—all call for a bleed. Brake fluid also absorbs moisture over time, which lowers its boiling point and can contribute to brake fade under hard use. Many riders refresh the fluid on a regular schedule even when the brakes still feel normal, because clean fluid is cheap insurance for a safety-critical system.

Tools and Supplies to Have Ready

  • Fresh brake fluid of the type marked on the master cylinder reservoir cap, from a sealed container
  • A box-end wrench that fits the bleeder valve snugly
  • A length of clear tubing that fits tightly over the bleeder
  • A clean catch bottle for the old fluid
  • Rags or shop towels, plus a syringe or turkey baster for removing old fluid from the reservoir
  • A screwdriver or driver that fits the reservoir cap screws
  • Optional: a one-way check-valve bleeder or a vacuum bleeder, which can make the job easier for one person

Clear tubing matters because it lets you watch the fluid for bubbles and color change. The catch bottle should be stable enough that it will not tip when you route the tube into it. Keep the fresh fluid capped until you are ready to pour, and do not reuse fluid that has been sitting open or that has been pulled through the system.

Set Up Before Opening the Hydraulic System

Support the EX500A securely upright on a stand so it cannot tip while you are working the lever or pedal. Turn the handlebars so the front reservoir sits level before you remove the cap. Cover painted surfaces, plastics, and the instrument area with rags, because most brake fluids damage paint and plastic on contact. If a spill happens, wipe it up immediately and rinse the area with water. Work in a well-ventilated space, and keep the reservoir cap and diaphragm clean and off the floor while they are removed.

Bleeding the Front Brake

  1. Open the front master cylinder reservoir and use the syringe or turkey baster to remove most of the old fluid. Do not let the reservoir run dry, because that can pull air into the system.
  2. Refill the reservoir with fresh fluid of the type marked on the cap, leaving room for the diaphragm and cap to go back on later.
  3. Fit the clear tubing over the front caliper bleeder and route the other end into the catch bottle. Make sure the tube fits snugly so air cannot sneak in around it.
  4. Squeeze and hold the front lever. With the lever held, open the bleeder about a quarter turn and let fluid and air escape through the tube.
  5. Close the bleeder before you release the lever. Releasing the lever with the bleeder open can draw air back into the caliper.
  6. Repeat the squeeze-hold-open-close-release sequence, checking the reservoir level often and topping it off with fresh fluid so it never runs low.
  7. Continue until the fluid coming through the tube is fresh, clean, and free of bubbles. As a general rule, start with the caliper farthest from the master cylinder; on this EX500A the front circuit has its own caliper and bleeder, so treat it as one complete job before moving to the rear.

Bleeding the Rear Brake

  1. Open the rear master cylinder reservoir and remove most of the old fluid with the syringe or baster, again without letting the reservoir run dry.
  2. Refill with fresh fluid of the type marked on the reservoir cap.
  3. Attach the clear tubing to the rear caliper bleeder and route it into the catch bottle.
  4. Press and hold the rear brake pedal. While holding it, open the bleeder about a quarter turn to let fluid and air out.
  5. Close the bleeder before releasing the pedal. This is the same critical order as the front: close first, then release.
  6. Repeat until the fluid in the tube is clean and bubble-free, topping off the rear reservoir throughout the process.
  7. Check the rear reservoir level one final time before you reinstall the diaphragm and cap.

Finishing, Testing, and When to Stop

When both circuits are bled, tighten each bleeder snugly without overtightening. Fill each reservoir to the correct level marking, reinstall the diaphragm and cap, and clean any spilled fluid from the calipers, lines, and surrounding bodywork. Check for leaks at the bleeder and at the banjo fittings before you ride. The front lever and rear pedal should feel firm and consistent, not spongy, and they should not slowly sink under steady pressure. Spin each wheel to confirm the brakes are not dragging, then test the brakes at low speed in a safe area before riding normally.

If the lever or pedal will not firm up after several bleeding attempts, if it firms only after pumping, if bubbles keep appearing, or if fluid is leaking from the master cylinder or caliper, stop and have a shop inspect the system. This EX500A has no ABS unit or linked-brake hardware, so you do not have to deal with a dealer-level ABS bleed sequence here, but a persistent soft lever still points to a problem that needs proper diagnosis rather than more pumping.

Related Shopping Categories

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Shop Brake Tools for a 1991 Kawasaki EX500A Motorcycle.

Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.