Bleeding the Brakes on a 2017 Kawasaki Ninja 300 ABS
Shop parts for a 2017 Kawasaki EX300 - Ninja 300 ABS Motorcycle.What You Are Working With on the EX300 ABS
The 2017 Kawasaki Ninja 300 ABS uses hydraulic disc brakes at both ends. Up front, a master cylinder on the handlebar feeds the front caliper; out back, a pedal-driven master cylinder near the right footpeg feeds the rear caliper. Both circuits pass through an ABS modulator, but they remain two separate hydraulic systems, so each one is bled on its own. Because this bike carries the ABS designation, treat the modulator as a component you never want to fill with air. A routine fluid refresh done entirely through the caliper bleeders keeps the system healthy without disturbing the ABS unit, and that is precisely what this article walks you through.
When a Bleed Is Actually Needed
Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. That moisture lowers the fluid’s boiling point, and a boiled fluid creates vapor in the lines — which feels exactly like air and shows up as fade when you are working the brakes hard. Many riders therefore refresh the fluid on a regular interval even when nothing feels wrong.
Bleed sooner if the lever feels soft or spongy, if it now travels closer to the grip than it used to, if the fluid in the reservoir looks dark or cloudy, or if you have just had the system open for any reason: new lines, caliper service, or master cylinder work. Any of those situations means air has a way in, and air has to come out.
Tools and Supplies to Have Ready
- Fresh brake fluid of the type marked on the master cylinder reservoir cap, from a sealed container — once a container is opened, it starts absorbing moisture
- A box-end wrench that fits the bleeder valve snugly
- Clear tubing sized to fit tightly over the bleeder nipple
- A small catch bottle for the old fluid
- Rags or shop towels, plus a syringe or turkey baster for pulling old fluid out of the reservoir
- The correct driver for the reservoir cap screws
- Optional but helpful: a one-way check-valve bleeder or a vacuum bleeder, which makes a one-person job much less fiddly
- A rear stand or another way to hold the bike securely upright
Setting Up Without Damaging the Bike
Get the Ninja 300 on a stand so it sits upright and stable. For the front circuit, turn the handlebars until the reservoir on the master cylinder sits level — an angled reservoir will spill the moment you open it. Before you touch the cap, drape rags over the tank area, the plastics, the instrument cluster, and anything painted below the reservoir. Brake fluid attacks paint and many plastics on contact, and a single drip left sitting can leave a permanent mark. If a spill does happen, wipe it up immediately and rinse the area with water rather than waiting until the end of the job.
The Bleeding Procedure, Step by Step
- Start with the front brake. With the bars turned so the reservoir is level, remove the cap screws, lift out the diaphragm, and set both aside somewhere clean where they will not pick up grit.
- Use the syringe or baster to draw most of the old fluid out of the reservoir. Leave enough to cover the port at the bottom — do not let the reservoir run dry at any point in this job.
- Top the reservoir up with fresh fluid from the sealed container.
- Push the clear tubing onto the bleeder valve and route the other end into the catch bottle. Keep the bottle below the caliper so fluid and air travel downhill.
- Squeeze the front lever and hold it steady. Do not release it yet.
- Open the bleeder about a quarter turn. Fluid, and any air behind it, will push out through the tubing. Watch the tube rather than the lever.
- Close the bleeder before you let the lever go. Releasing with the valve open is the classic way to suck air back into the caliper.
- Repeat the squeeze–hold–open–close–release cycle, checking the reservoir level every few pumps and topping it off as needed.
- Keep going until the fluid coming through the tubing is clean and free of bubbles, then move to the rear circuit and repeat the same sequence using the pedal instead of the lever. The rear reservoir is at the rear master cylinder, so check its level just as carefully.
- If your bike has two front calipers, bleed each one in turn. A useful general habit is to begin with the caliper farthest from the master cylinder and work toward the closest.
Closing Up and Checking for Leaks
When the fluid runs clean at both ends, tighten each bleeder snugly with the box-end wrench. Snug is the goal — these are small fittings, and overtightening can damage the seat. Pull the tubing off and wipe the caliper dry. Fill each reservoir to the level marking, reinstall the diaphragm and cap, and wipe down every surface you touched. Then look closely at the bleeder valves and at the banjo fittings at the master cylinder and caliper for any weeping or wetness. A dry paper towel pressed against a fitting will show a leak that your eyes might miss.
Testing Before You Ride
Pull the front lever and press the rear pedal. Both should feel firm and consistent, and neither should slowly sink while you hold steady pressure. Spin each wheel by hand to confirm the brakes are not dragging. Then, in a safe open area, test the brakes at low speed before riding normally. If anything feels vague at that first gentle stop, go back and bleed again rather than telling yourself it will firm up on the road.
When This Job Belongs in a Shop
Some problems are not solved at the bleeder. If the lever will not firm up after several honest attempts, if it only firms after repeated pumping, if bubbles keep appearing no matter how long you bleed, or if you find fluid weeping from the master cylinder or a caliper, stop and have the bike inspected. The same applies if the reservoir ever ran dry, or if the ABS unit or its lines were disconnected — air trapped inside the modulator may need a dealer-level procedure or diagnostic tool to clear, and no amount of pumping at the caliper will get it out. Recognizing that boundary is part of doing this job well.
Related Shopping Categories
Shop Brake Fluid for a 2017 Kawasaki EX300 - Ninja 300 ABS Motorcycle.
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Shop Brake Pads for a 2017 Kawasaki EX300 - Ninja 300 ABS Motorcycle.
Shop Stands for a 2017 Kawasaki EX300 - Ninja 300 ABS Motorcycle.
Shop Brake Tools for a 2017 Kawasaki EX300 - Ninja 300 ABS 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.
