Bleeding the Brakes on a 2020 Honda CB650R ABS
Shop parts for a 2020 Honda CB650R ABS Motorcycle.
What You Are Working With on This Bike
The 2020 CB650R ABS runs hydraulic disc brakes at both ends, with an anti-lock braking system supervising the front and rear circuits. That gives you two independent hydraulic systems to service: a front circuit fed by the master cylinder on the right handlebar, and a rear circuit fed by the pedal master cylinder. Each is bled separately, and each has its own reservoir to keep topped off. The front brake carries a caliper on each fork leg, so the front half of the job means working two bleed points in turn rather than one. The ABS modulator sits between the master cylinders and the calipers, which is the detail that decides whether this stays a garage job or becomes a shop job.
Signs That the Fluid Needs Attention
Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. That moisture lowers the fluid’s boiling point, and a boiling fluid creates vapor in the lines — which feels exactly like air in the system and shows up as fade when you are working the brakes hard. This is why many riders refresh the fluid on a schedule even when nothing feels wrong.
On the other side of the coin are the symptoms that demand action now. A front lever that feels spongy or pulls closer to the grip than it used to. A rear pedal with a soft, vague first part of its travel. Fluid in either reservoir that has gone dark, cloudy, or gritty. Any recent work that opened the hydraulic system — new lines, a caliper rebuild, master cylinder service, or a reservoir that ran dry — leaves air behind that has to be purged before the bike is safe to ride.
Tools and Supplies to Have Ready
- 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 valves 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 reservoirs
- The correct driver for the reservoir cap screws
- Optional: a one-way check-valve bleeder or a vacuum bleeder, both of which make a solo job much less fiddly
Buy more fluid than you think you need. Once a container is opened it starts absorbing moisture, so a partial bottle is not something to save for next season.
Setting Up Before You Open Anything
Get the bike on a stand so it sits securely upright and cannot tip while you are leaning on the lever. Turn the handlebars until the front reservoir sits level, since a tilted reservoir spills the moment the cap comes off. Then drape rags over the tank, the surrounding plastics, the instrument cluster, and anything else below the reservoirs and calipers. Brake fluid attacks paint and clear plastic on contact, so wipe up any drip immediately and rinse the area with water if it reaches a painted surface.
The Bleeding Procedure, Step by Step
- Start with the front circuit. Remove the reservoir cap and diaphragm, then use the syringe or baster to draw most of the old fluid out. Leave a little in the bottom so you do not push air into the master cylinder.
- Refill with fresh fluid from the sealed container, keeping the level well above the minimum as you work.
- 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’s end stays submerged.
- Squeeze the front lever and hold it firm. While you hold it, open the bleeder about a quarter turn. Fluid and any trapped air will push out through the tube.
- Close the bleeder before you release the lever. Releasing with the valve open draws air straight back into the caliper, which is the single most common way this job goes wrong.
- Repeat the squeeze–hold–open–close–release cycle, topping off the reservoir every few strokes so it never runs low enough to swallow air.
- Move to the second front caliper and repeat the same cycle there. Working the caliper farthest from the master cylinder first is the usual practice, then finishing on the nearer one.
- Continue until the fluid coming through the tube is clean and free of bubbles, then top the reservoir to the level marking.
- Repeat the entire process at the rear, using the pedal instead of the lever. Press and hold the pedal, crack the rear bleeder, close it, then release.
Closing It Out and Checking for Leaks
Tighten each bleeder snugly with the box-end wrench — firm enough to seal, never so hard that you risk damaging the caliper threads. Reinstall the diaphragm and cap on both reservoirs, wipe down every surface you touched, and inspect the bleeder valves and the banjo fittings at the master cylinders and calipers for weeping. A dry paper towel wiped around each fitting tells you quickly whether anything is seeping.
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, in a safe open area, test the brakes at low speed before riding normally.
If the lever refuses to firm up after several rounds, if it only firms up after pumping, if bubbles keep appearing, or if fluid is leaking from the master cylinder or a caliper, stop and diagnose rather than ride. And if the reservoir ever ran dry, or the ABS unit or its lines were disconnected, air may be trapped inside the modulator — that requires a dealer-level procedure or diagnostic tool, so send the bike to a shop.
Related Shopping Categories
Shop Brake Fluid for a 2020 Honda CB650R ABS Motorcycle.
Shop Brake Lines for a 2020 Honda CB650R ABS Motorcycle.
Shop Brake Pads for a 2020 Honda CB650R ABS Motorcycle.
Shop Stands for a 2020 Honda CB650R ABS Motorcycle.
Shop Brake Tools for a 2020 Honda CB650R 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.
