Bleeding the ABS Brakes on a 2023 Honda Grom
Shop parts for a 2023 Honda Grom ABS Motorcycle.
The 2023 Honda Grom ABS uses hydraulic disc brakes at both ends, and the ABS hardware is part of those hydraulic circuits. For a routine fluid refresh or a normal air bleed, the work is done at the caliper bleeders—front and rear—just as it would be on a non-ABS machine, provided the ABS unit itself has not taken in air. If the reservoir has run dry, the ABS unit or its lines have been disconnected, or you suspect air is trapped inside the ABS hardware, stop and send the bike to a shop with the correct diagnostic equipment. This guide covers the home-garage bleed for the Grom ABS and the points where it is smarter to hand the job off.
Why and When the Grom ABS Needs a Bleed
A spongy front lever or a rear pedal that feels soft and long is the classic sign that air or old fluid is affecting the hydraulic system. You may also notice the lever pulling closer to the grip than it used to, or the brake feeling inconsistent from one stop to the next. Dark, cloudy, or contaminated fluid in either reservoir is another reason to flush the system. Bleeding is also required after work that opened the hydraulics, such as replacing a brake line, servicing a caliper, or repairing the master cylinder.
Even when the brakes feel normal, brake fluid absorbs moisture over time. That moisture lowers the fluid’s boiling point, which can lead to brake fade under hard or repeated use. Many riders refresh the fluid on a regular schedule as preventive maintenance rather than waiting for a soft lever. On the Grom ABS, treat the front and rear as separate hydraulic circuits and bleed each one completely.
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 valve
- A small catch bottle for used fluid
- Rags or shop towels, plus water for rinsing spills
- A syringe or turkey baster for removing old fluid from the reservoir
- The correct driver for 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 lever-and-bleeder method works fine with patience. Do not reuse fluid that has been through the system, and keep the fresh container capped when it is not being poured.
Preparing the Bike and Protecting the Finish
Support the Grom securely upright on a stand so it cannot tip while you are working the lever or pedal. Turn the handlebars so the front master cylinder reservoir sits level before you open it. Brake fluid damages paint and many plastics on contact, so cover the tank area, bodywork, instrument cluster, and any painted surfaces around both reservoirs with rags or shop towels. If a spill happens, wipe it up immediately and rinse the area with water.
Clean around the reservoir cap before removing it so dirt does not fall into the fluid. Have your catch bottle positioned before you open the bleeder, and keep the reservoir cap and diaphragm clean and close at hand. The goal is to keep the system closed to contamination while allowing air and old fluid to escape at the caliper.
Step-by-Step Bleeding Procedure
- With the bike upright and the front reservoir level, remove the cap and diaphragm. Use a syringe or turkey baster to lift most of the old fluid out of the reservoir, leaving enough to keep the outlet covered so you do not push air into the master cylinder.
- Refill the reservoir with fresh fluid from the sealed container, up to the upper level marking. Keep the reservoir open but protected from drips and debris.
- Fit the clear tubing over the front caliper bleeder valve and route the other end into the catch bottle. Position the bottle so you can see the fluid coming through the tube.
- Place the box-end wrench on the bleeder valve. Squeeze the front brake lever slowly and hold it firm against the grip.
- Open the bleeder about a quarter turn. Fluid and any trapped air will move through the tube. Watch the tube, not the reservoir, while the bleeder is open.
- Close the bleeder before you release the lever. This order matters: releasing the lever with the bleeder open can draw air back into the caliper.
- Release the lever, then check the reservoir level and top it off with fresh fluid. Repeat the squeeze-hold-open-close-release sequence until clean, bubble-free fluid comes through the tube.
- Keep the reservoir from running low at any point. If it draws air, you will have to bleed that air out again, and on an ABS bike you do not want to risk pushing air into the ABS unit.
- Move to the rear brake and repeat the same process with the rear pedal and rear caliper bleeder. Press and hold the pedal, open the bleeder, close it before releasing the pedal, and top off the rear reservoir as needed.
- If you are working on a system with more than one caliper on the same circuit, bleed the caliper farthest from the master cylinder first. The Grom ABS uses separate front and rear circuits, so complete the front, then complete the rear.
Finishing Up and Checking for Leaks
Once clean fluid comes through at both ends, tighten each bleeder snugly without overtightening. Fill each reservoir to the correct level marking, reinstall the diaphragm and cap, and wipe away any fluid residue. Check the bleeder valves and the banjo fittings at the master cylinders and calipers for weeping or drips. A dry fitting after several firm lever and pedal applications is a good sign; a wet fitting needs attention before the bike is ridden.
Spin each wheel by hand to confirm the brakes are not dragging. The front lever and rear pedal should feel firm and consistent, not spongy, and they should not slowly sink while you hold steady pressure. Test the brakes at low speed in a safe area before riding normally. If either brake feels different from what you expect, stop and investigate rather than assuming it will improve.
Troubleshooting and When to See a Shop
If the lever or pedal will not firm up after several careful bleeding attempts, or if it firms only after you pump it, air is still in the system or fluid is bypassing internally. Persistent bubbles at the bleeder, fluid leaking from the master cylinder or caliper, and a lever that slowly sinks under steady pressure are all reasons to stop riding and diagnose the problem. Because this is the ABS model, any situation where the reservoir ran dry, the ABS unit was disturbed, or you suspect air entered the ABS hardware is best handled by a shop with the appropriate diagnostic tools. Do not try to force air out of the ABS unit by repeated pumping. A professional bleed is cheaper than a brake system that fails when you need it most.
Related Shopping Categories
Shop Brake Fluid for a 2023 Honda Grom ABS Motorcycle.
Shop Brake Lines for a 2023 Honda Grom ABS Motorcycle.
Shop Brake Pads for a 2023 Honda Grom ABS Motorcycle.
Shop Stands for a 2023 Honda Grom ABS Motorcycle.
Shop Brake Tools for a 2023 Honda Grom 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.
