Bleeding the Brakes on a 2018 Honda Grom ABS
Shop parts for a 2018 Honda Grom ABS Motorcycle.The 2018 Honda Grom ABS is a small street bike with hydraulic disc brakes at both ends, and the ABS version adds an anti-lock modulator to the hydraulic system. That matters for a brake bleed: routine fluid replacement and air removal are still done at the calipers, but air that has traveled into the ABS unit is a different problem. This MotoSport guide covers a normal front and rear bleed on the Grom ABS, including the checks that tell you when the job should go to a shop.
Why and When to Bleed the Grom ABS Brakes
Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. Moisture lowers the fluid’s boiling point, so hard use can create vapor in the system and a lever or pedal that feels soft or fades. Even if the Grom is not showing symptoms, dark, cloudy, or contaminated fluid in the reservoir is a sign that fresh fluid is due. A spongy front lever, a rear pedal that travels farther than it used to, or a lever that pulls closer to the grip can all point to air in the lines. Bleeding is also required after any work that opened the hydraulic system, such as new brake lines, caliper service, or master cylinder work.
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 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.
- A screwdriver that fits 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 if you have a helper or a way to hold pressure.
Setting Up the Bike Safely
Support the Grom securely upright on a stand so it cannot tip while you are working. Position the bike and turn the handlebars so the reservoir you are opening sits level; a tilted reservoir can spill fluid as soon as the cap comes off. Cover painted bodywork, plastic panels, and the instrument area with rags. Brake fluid damages paint and many plastics on contact, so wipe up any spill immediately and rinse the area with water. Work in a well-ventilated space and keep the fluid container closed when you are not pouring from it.
The Step-by-Step Bleeding Procedure
- Start with the front brake. Remove the reservoir cap and diaphragm, then use the syringe or baster to remove most of the old fluid from the reservoir. Do not let the reservoir run dry.
- Refill the reservoir with fresh fluid of the type marked on the cap, leaving room for the diaphragm and cap to go back on later.
- Push the clear tubing onto the front caliper bleeder valve and route the other end into the catch bottle. Keep the bottle below the caliper so fluid and air can flow away.
- Squeeze the front lever slowly and hold it against the grip. Keep steady pressure on it.
- Open the bleeder valve about a quarter turn with the box-end wrench. Fluid and air will move through the tube. Close the bleeder before you release the lever.
- Release the lever, then repeat the squeeze-hold-open-close sequence. Check the reservoir often and top it off so it never draws air.
- Continue until the fluid coming through the tube is fresh, clean, and free of bubbles, and the lever feels firm. On a system with more than one caliper on the same circuit, bleed one caliper at a time and start with the caliper farthest from the master cylinder; on the Grom, each brake circuit is handled on its own.
- When the front is done, tighten the bleeder snugly without overtightening, refill the reservoir to the correct level marking, and reinstall the diaphragm and cap.
- Move to the rear brake. Open the rear reservoir, remove most of the old fluid, and refill with fresh fluid. Attach the clear tube to the rear caliper bleeder and route it to the catch bottle.
- Press and hold the rear pedal, open the bleeder about a quarter turn, then close it before releasing the pedal. Repeat until the fluid is clean and bubble-free and the pedal feels firm, topping off the reservoir as you go.
- Tighten the rear bleeder snugly, set the rear reservoir to the correct level, and reinstall its diaphragm and cap.
- Clean any spilled fluid from the calipers, reservoirs, and bodywork, then check the bleeder valves and banjo fittings for leaks.
Finishing Checks and Test Ride
Before riding, pump the front lever and rear pedal a few times and hold steady pressure on each. They should feel firm and consistent, not spongy, and they should not slowly sink while you hold them. Spin each wheel to confirm the brakes are not dragging. Test the brakes at low speed in a safe area, such as a parking lot, before riding normally. If the lever or pedal changes feel after the test, stop and investigate before using the bike in traffic.
Troubleshooting and When to Visit a Shop
If the lever or pedal will not firm up after several bleeding attempts, or if it firms only after pumping, air is still in the system. Persistent bubbles, fluid leaking from the master cylinder or caliper, or a bleeder that will not seal are reasons to stop and inspect. Because this is the Grom ABS, there is an ABS modulator in the hydraulic system. A normal bleed through the caliper bleeders is generally used to refresh fluid, but if the reservoir ran dry, or if the ABS unit or its lines were disconnected, air may have entered the modulator. That situation may require a dealer-level procedure or diagnostic tool, so it is best handled by a shop. The same advice applies if you are not confident that you can keep the reservoir from running dry or if the brakes do not feel correct after a careful bleed.
Related Shopping Categories
Shop Brake Fluid for a 2018 Honda Grom ABS Motorcycle.
Shop Brake Lines for a 2018 Honda Grom ABS Motorcycle.
Shop Brake Pads for a 2018 Honda Grom ABS Motorcycle.
Shop Stands for a 2018 Honda Grom ABS Motorcycle.
Shop Brake Tools for a 2018 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.
