How to Bleed the Brakes on a 2016 Kawasaki Ninja 300

Shop parts for a 2016 Kawasaki EX300 - Ninja 300 Motorcycle.

Confirm What Your EX300 Is Working With

The 2016 Kawasaki Ninja 300 uses hydraulic disc brakes at both ends, so this job covers two separate systems: the front brake, operated by the lever on the right handlebar, and the rear brake, operated by the pedal on the right footpeg bracket. Each has its own master cylinder, its own reservoir, and its own caliper with a bleeder valve, which means each gets bled on its own. Kawasaki offered the EX300 with and without anti-lock brakes that year, so take a moment to identify your bike before you start. An ABS-equipped Ninja 300 will typically show an ABS indicator on the dash at key-on and will have a tone ring and wheel speed sensor at the hubs. If your bike has ABS, a normal bleed through the caliper bleeder is still the right approach for routine fluid refreshment. What changes is the failure case: if the reservoir ever ran dry, or if the ABS unit or its lines were disconnected, air can be trapped inside the modulator where a hand bleed will not reach it. That situation calls for a dealer-level procedure, and it is covered further down.

Recognizing When the Fluid Needs Attention

Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. That absorbed water lowers the fluid's boiling point, and a boiling fluid creates vapor pockets that feel exactly like air in the lines — a lever that goes soft or long right when you need braking most. Because of this, many riders refresh the fluid on a regular interval whether or not anything feels wrong. Beyond scheduled maintenance, bleed the Ninja 300 when the lever or pedal feels spongy, when the lever travels noticeably closer to the grip than it used to, when the fluid visible in the reservoir looks dark or cloudy rather than clear, or after any work that opened the hydraulic system. That includes new brake lines, caliper service, master cylinder work, or a fluid top-off that let the reservoir run low enough to gulp air.

Tools and Supplies to Have Ready

  • Fresh brake fluid of the type printed on the master cylinder reservoir cap, from a sealed container — opened fluid absorbs moisture, so do not use a bottle that has been sitting around
  • A box-end wrench that fits the bleeder valve snugly; a box-end grips better than an open-end and is less likely to round the hex
  • A length of clear tubing that fits tightly over the bleeder nipple, plus a small catch bottle to route it into
  • Rags or shop towels, and a syringe or turkey baster for pulling old fluid out of the reservoir
  • The correct driver for the reservoir cap screws
  • Optional but helpful for a solo job: a one-way check-valve bleeder or a vacuum bleeder

Setting Up Before You Open Anything

Get the bike supported securely upright on a stand so it cannot tip while you are working the lever. For the front circuit, turn the handlebars until the reservoir on the master cylinder sits level — a tilted reservoir will spill. Brake fluid attacks paint, clearcoat, and many plastics on contact, so drape rags over the tank, the upper fairing, the dash, and anything else below the reservoir before you loosen the cap. If a drop does land on a painted surface, wipe it up immediately and rinse the area with water rather than letting it sit.

Bleeding the Front Brake

  1. Remove the reservoir cap and diaphragm, then use the syringe or baster to draw most of the old fluid out of the reservoir. Leave a little in the bottom so you do not push air into the master cylinder.
  2. Refill with fresh fluid from the sealed container, taking care not to splash.
  3. Slip the clear tubing over the front caliper bleeder and route the other end into the catch bottle, with the bottle positioned so you can see the fluid moving through the tube.
  4. Squeeze the front lever slowly and hold it against the grip.
  5. With the lever held, open the bleeder about a quarter turn. Fluid and any trapped air will push out through the tube. Watch the tube, not the reservoir, while the bleeder is open.
  6. Close the bleeder before you release the lever. Releasing with the bleeder open draws air back in through the nipple, which is the single most common way a home bleed goes wrong.
  7. Release the lever, then repeat the squeeze–hold–open–close–release cycle. Check the reservoir level every few cycles and top it off so it never runs low enough to pull air into the master cylinder.
  8. Keep cycling until the fluid coming through the tube runs clean and bright with no bubbles, and the lever feels firm rather than spongy.

If your bike has more than one front caliper, bleed each one in turn rather than trying to do both at once. As a general practice, start with the caliper farthest from the master cylinder in terms of hydraulic path, then move to the closer one.

Bleeding the Rear Brake

  1. Open the rear reservoir, which on the Ninja 300 sits near the right footpeg area, and remove most of the old fluid with the syringe.
  2. Top it up with fresh fluid and fit the clear tubing over the rear caliper bleeder, routing it into the catch bottle.
  3. Press and hold the brake pedal down.
  4. Open the bleeder a quarter turn, let fluid and air escape, then close it before releasing the pedal.
  5. Release the pedal and repeat, watching the reservoir level and topping off as needed, until the fluid runs clean and bubble-free and the pedal feels solid.

Finishing Up and Confirming the Job

Once both circuits are bled, snug the bleeder valves down firmly without overtightening — you are sealing a small tapered seat, and excess force can damage it. Fill each reservoir to the level marking on the body, reinstall the diaphragm and cap, and wipe away any residue. Look closely at the bleeder valves and at the banjo fittings at the master cylinder and caliper for weeping or dampness. Then test before you ride: the lever and pedal should feel firm and consistent, and should not slowly sink while you hold steady pressure. Spin each wheel and confirm the brake is not dragging. Finally, ride the bike at low speed in a safe, open area and apply each brake individually before trusting them in traffic.

When This Job Belongs at a Shop

Stop and get professional help if the lever or pedal will not firm up after several full bleeding cycles, if it only firms up after pumping, if bubbles keep appearing no matter how long you bleed, or if you find fluid leaking from the master cylinder or a caliper. On an ABS-equipped Ninja 300, any event that may have pushed air into the ABS unit itself — a reservoir run dry, a disconnected line, or modulator service — is a shop job, because the modulator needs a dealer-level procedure to purge correctly. A brake system that will not hold pressure is not something to test on the road.

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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.