How To Bleed 2019 Kawasaki EX400 - Ninja 400 Motorcycle Brakes

Bleeding the Brakes on a 2019 Kawasaki Ninja 400

Know the System Before You Open It

The 2019 Kawasaki EX400 Ninja 400 uses hydraulic disc brakes at both ends, so the front lever and the rear pedal each push fluid through a closed circuit to apply the brake. ABS was offered on this model, so check your own bike for the ABS indicator or hardware before you begin. A normal bleed through the caliper bleeders is the usual way to refresh fluid and remove air from the lines and calipers. If air has entered the ABS unit itself—for example, because the reservoir ran dry or the ABS unit or its lines were disconnected—the bike may need a dealer-level procedure or diagnostic tool, and that portion of the job should go to a shop. This article covers bleeding the front and rear hydraulic circuits. It does not cover replacing pads, rotors, calipers, or lines, though those jobs are common reasons a bleed is needed afterward.

When a Bleed Is Due

A spongy or soft lever or pedal is the classic sign that air is in the system. So is a lever that pulls closer to the grip than it used to, or a pedal that feels longer and less definite. Dark or cloudy fluid in the reservoir is another reason to flush the system, and any work that opened the hydraulic circuit—new lines, caliper service, or master cylinder work—should be followed by a bleed. Brake fluid absorbs moisture over time, which lowers its boiling point and can lead to brake fade under hard use. That is why many riders refresh the fluid on a regular schedule even when the brakes still feel normal.

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
• Clear tubing that fits snugly over the bleeder
• A catch bottle for old fluid
• Rags or shop towels
• A syringe or turkey baster for removing old fluid from the reservoir
• A screwdriver or driver that fits the reservoir cap screws

A one-way check-valve bleeder or a vacuum bleeder can make the job easier when you are working alone, but the manual squeeze-and-hold method works fine with a little patience. Use only fresh fluid from a sealed container, and use the fluid type marked on the reservoir cap for this Ninja 400.

Preparation and Paint Protection

Support the bike securely upright on a stand so the reservoirs sit at a stable angle. Turn the handlebars so the front reservoir is 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. Remove the reservoir cap and diaphragm, and keep them clean and covered while you work.

Bleeding the Front Brake

If your bike is fitted with more than one front caliper, treat each caliper as its own bleed point and finish one before moving to the next. As a general rule, begin with the caliper farthest from the master cylinder. On a single-caliper front, that is simply the one you have.

1. Use the syringe or turkey baster to remove most of the old fluid from the front reservoir without letting the reservoir run dry. Refill with fresh fluid to the level marking.
2. Fit the box-end wrench onto the front bleeder valve, then push the clear tubing snugly onto the bleeder and route the other end into the catch bottle. Keep the bottle lower than the bleeder.
3. Squeeze the front lever slowly and hold it firm. Open the bleeder about a quarter turn and let fluid and air escape through the tube. Close the bleeder before you release the lever. Never release the lever while the bleeder is open, or air can be drawn back in.
4. Repeat the squeeze-hold-open-close-release sequence, topping off the reservoir as needed, until fresh, clean, bubble-free fluid comes through the tube. Keep the reservoir from running low enough to draw air into the master cylinder.
5. If there is a second front caliper, repeat the same sequence on that caliper, then recheck the first one if the lever still feels soft.
6. When the fluid runs clean and no bubbles appear, close the bleeder snugly without overtightening. Fill the reservoir to the correct level marking, reinstall the diaphragm and cap, and wipe away any spilled fluid.

Bleeding the Rear Brake

The rear circuit on this Ninja 400 is hydraulic as well, so it uses the same basic method with the rear pedal instead of the front lever. Work with the bike upright and the rear reservoir level.

1. Check the rear reservoir level and remove most of the old fluid if the reservoir is accessible. Refill with fresh fluid of the type marked on the cap.
2. Fit the box-end wrench and clear tubing to the rear bleeder, routing the tube into the catch bottle.
3. Press the rear pedal and hold it firm. Open the bleeder about a quarter turn, let fluid and air out, then close the bleeder before releasing the pedal.
4. Repeat the press-hold-open-close-release sequence, topping off the rear reservoir as needed, until the fluid is clean and bubble-free.
5. Close the bleeder snugly without overtightening, fill the reservoir to the marking, reinstall the diaphragm and cap, and clean up any spilled fluid.

Finishing Checks and a Low-Speed Test

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 either brake feels soft or inconsistent, do not ride the bike until the problem is resolved.

If the Brakes Will Not Firm Up

A lever or pedal that will not firm up after several bleeding attempts, one that firms only after pumping, persistent air bubbles, or fluid leaking from the master cylinder or caliper are all reasons to stop and let a shop inspect the system. The same applies if air may have entered an ABS unit. Brakes are a safety-critical system, and a spongy lever is not something to ride around hoping it improves.

Related Shopping Categories

Shop Brake Fluid for a 2019 Kawasaki EX400 - Ninja 400 Motorcycle.

Shop Brake Lines for a 2019 Kawasaki EX400 - Ninja 400 Motorcycle.

Shop Brake Pads for a 2019 Kawasaki EX400 - Ninja 400 Motorcycle.

Shop Stands for a 2019 Kawasaki EX400 - Ninja 400 Motorcycle.

Shop Brake Tools for a 2019 Kawasaki EX400 - Ninja 400 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.