How to Bleed the Brakes on a 2019 Kawasaki EX400 Ninja 400 ABS

Shop parts for a 2019 Kawasaki EX400 - Ninja 400 ABS Motorcycle.

The 2019 Kawasaki EX400 Ninja 400 ABS uses hydraulic disc brakes at both wheels, with the front operated by the lever and the rear by the pedal. Because this is the ABS model, the system also includes an ABS unit in the hydraulic circuit. A normal bleed through the caliper bleeders is the right way to refresh fluid and remove air from the lines and calipers, but if air has entered the ABS unit itself, the job can move beyond a home garage. This guide walks you through a careful, methodical bleed for the EX400 ABS so you can restore a firm lever and pedal and know when to stop and hand the bike to a shop.

What the EX400 ABS Brake Layout Means for Bleeding

Treat the front and rear brakes as two separate hydraulic circuits. The front circuit runs from the master cylinder at the lever down to the front caliper, and the rear circuit runs from its master cylinder to the rear caliper. Each circuit has its own reservoir, its own bleeder at the caliper, and its own lever or pedal feel. That means you should finish one circuit completely before moving to the other, and you should keep each reservoir topped off while you work on that circuit. The ABS unit sits in the system and is normally not bled directly during a routine caliper bleed. If the reservoir has run dry, if the ABS unit or its lines have been disconnected, or if the system has been opened in a way that let air travel into the ABS hardware, the bike may need a dealer-level procedure or diagnostic tool. Do not try to invent an ABS bleed sequence at home.

When a Bleed Is Due—and Why It Matters

Bleed the brakes when the lever or pedal feels spongy, when the lever pulls closer to the grip than it used to, when the fluid in the reservoir looks dark or cloudy, or after any work that opened the hydraulic system, such as new lines, caliper service, or master cylinder work. Brake fluid 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 acceptable, because clean fluid and a properly bled system are cheap insurance for a safety-critical circuit. On the Ninja 400 ABS, a soft lever is a clear sign that air or old fluid is affecting the front circuit, while a low or spongy rear pedal points to the rear circuit.

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 used fluid
  • Rags or shop towels, plus a syringe or turkey baster for removing old fluid from the reservoir
  • A screwdriver or driver that matches the reservoir cap screws
  • Optional: a one-way check-valve bleeder or vacuum bleeder to make one-person bleeding easier

Set Up the Bike and Protect the Finish

Support the bike 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 open it. 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. Keep the reservoir cap and diaphragm clean and set them aside where they will not pick up grit. Work in a well-ventilated area and keep used fluid away from children, pets, and painted surfaces.

Bleeding the Front and Rear Hydraulic Brakes

Work on one circuit at a time. Within a circuit, start at the caliper farthest from its master cylinder if there is more than one bleed point; on this bike, use the caliper bleeder for the circuit you are servicing. The steps below apply to the front brake first, then repeat the same logic for the rear brake.

  1. Open the reservoir and use a syringe or turkey baster to remove most of the old fluid. Do not let the reservoir run dry, and do not let old fluid spill onto the bike.
  2. Refill the reservoir with fresh fluid of the type marked on the cap, leaving room for the diaphragm and cap later.
  3. Attach the clear tubing to the caliper bleeder and route the other end into the catch bottle. Make sure the tubing fits snugly so air cannot be drawn in around it.
  4. Fit the box-end wrench onto the bleeder. Squeeze and hold the front lever, or press and hold the rear pedal, and keep it held.
  5. Open the bleeder about a quarter turn to let fluid and air escape. Watch the tubing for bubbles and dirty fluid.
  6. Close the bleeder before you release the lever or pedal. Releasing first can pull air back into the caliper.
  7. Repeat the squeeze, hold, open, close, and release sequence until fresh, clean, bubble-free fluid comes through the tube. Keep topping off the reservoir throughout so it never runs low enough to draw air in.
  8. When the front circuit is clean and bubble-free, close the bleeder snugly, refill the reservoir to the correct level marking, and reinstall the diaphragm and cap. Then repeat the same procedure on the rear circuit using the rear pedal and rear caliper bleeder.

Finishing, Testing, and Knowing When to Stop

Tighten each bleeder snugly without overtightening, and check for leaks at the bleeder and at the banjo fittings. Clean any spilled fluid from the calipers, lines, and reservoir area. The lever and 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. Test the brakes at low speed in a safe area before riding normally.

If the lever or pedal will not firm up after several careful bleeding attempts, if it firms up 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. The same applies if the reservoir ran dry, if the ABS unit or its lines were disconnected, or if you are unsure whether air reached the ABS hardware. A professional can pressure-test the system and perform any ABS-specific procedure needed for the 2019 Ninja 400 ABS.

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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.