Bleeding the Brakes on a 2016 Honda CB300F

Shop parts for a 2016 Honda CB300F Motorcycle.

What You Are Working With

The 2016 Honda CB300F stops on hydraulic disc brakes at both ends. A master cylinder on the right handlebar feeds the front caliper, and a second master cylinder driven by the foot pedal feeds the rear. The two circuits are completely independent — the lever works only the front brake, the pedal only the rear — so each one has to be bled on its own. There is no drum brake on this bike and nothing to adjust with a cable. Some examples of this model were delivered with anti-lock brakes; if yours carries ABS hardware, read the shop note at the end before you begin, because air trapped inside the ABS unit is a different problem from air in the lines.

Why and When to Bleed

Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. Moisture lowers the fluid's boiling point, and boiling fluid creates vapor that behaves exactly like air in the line — the lever goes soft right when you need it most. That is why many riders flush the system on a schedule even when nothing feels wrong.

Bleed the brakes sooner if the lever or pedal feels spongy, if the lever 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 new lines, caliper work, or master cylinder service.

Tools and Supplies

  • Fresh brake fluid of the type printed on the master cylinder reservoir cap, from a sealed container
  • A box-end wrench that fits the bleeder valve snugly
  • Clear tubing that fits tightly over the bleeder nipple
  • A small catch bottle for the old fluid
  • Rags or shop towels, plus a syringe or turkey baster
  • The correct driver for the reservoir cap screws

A one-way check-valve bleeder or a vacuum bleeder makes the job much easier when you are working alone, since you no longer need a helper to work the lever.

Setting Up

Get the bike upright and stable on a stand. For the front circuit, turn the handlebar until the reservoir on the master cylinder sits level; a tilted reservoir will spill. Lay rags over the tank area, the plastics, the instrument cluster, and anything else below the reservoir, because brake fluid attacks paint and plastic on contact. If a drop lands anyway, wipe it up immediately and rinse the area with water.

Bleeding the Front Brake

  1. Remove the reservoir cap and diaphragm, then use the syringe or baster to pull most of the old fluid out. Leave a little in the bottom so you do not push air into the line.
  2. Top the reservoir up with fresh fluid from the sealed container.
  3. Push the clear tubing onto the front bleeder valve and route the other end into the catch bottle, with the bottle positioned so the tube runs uphill from the bleeder.
  4. Squeeze the front lever and hold it against the grip.
  5. Open the bleeder about a quarter turn with the box-end wrench. Fluid and air will push out through the tube.
  6. Close the bleeder before you release the lever. Releasing with the valve open draws air back in through the bleeder.
  7. Release the lever slowly and repeat. Check the reservoir every few pumps and top it off — letting it run dry pulls air into the master cylinder and undoes your work.
  8. Keep going until the fluid coming through the tube is clean and free of bubbles, then close the bleeder snugly.

If your bike has two front calipers, bleed them one at a time, starting with the caliper farthest from the master cylinder and finishing with the closer one.

Bleeding the Rear Brake

  1. Open the rear reservoir, remove most of the old fluid, and refill with fresh fluid.
  2. Fit the tubing over the rear bleeder and into the catch bottle.
  3. Press and hold the brake pedal.
  4. Open the bleeder a quarter turn, let fluid and air escape, then close it before releasing the pedal.
  5. Repeat, topping off the reservoir as you go, until the fluid runs clean and bubble-free.

Finishing Up

Tighten the bleeder snugly — firm, not forced. Over-tightening can damage the seat and cause a leak. Fill the reservoir to the level marking, reinstall the diaphragm and cap, and wipe down every surface you touched. Then look closely at the bleeder and at the banjo fittings at the master cylinder and caliper for any weeping or wetness.

Testing Before You Ride

Both the lever and the pedal 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 ride at low speed in a safe, empty area and apply each brake separately before trusting them at road speed.

When to Take It to a Shop

If the lever will not firm up after several rounds of bleeding, if it only firms up when you pump it, or if bubbles keep appearing no matter how long you work, stop and let a professional look at it. The same applies to fluid leaking from the master cylinder or caliper, and to any bike with ABS where the reservoir ran dry or the ABS unit or its lines were disconnected — that can require a dealer-level procedure to purge air from the unit itself.

Related Shopping Categories

Shop Brake Fluid for a 2016 Honda CB300F Motorcycle.

Shop Brake Lines for a 2016 Honda CB300F Motorcycle.

Shop Brake Pads for a 2016 Honda CB300F Motorcycle.

Shop Stands for a 2016 Honda CB300F Motorcycle.

Shop Brake Tools for a 2016 Honda CB300F 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.