Bleeding the Brakes on a 2019 Honda Grom: A Complete Flush Walkthrough
Shop parts for a 2019 Honda Grom Motorcycle.
The 2019 Honda Grom stops on hydraulic disc brakes at both ends, so a proper bleed means working two separate hydraulic circuits — one fed by the master cylinder on the handlebar, one fed by the master cylinder behind the right-side bodywork near the pedal. Some 2019 Groms were delivered with ABS; if your bike has it, you will see a wheel-speed sensor and tone ring at the hub and an ABS indicator in the dash. That distinction matters later, so take a moment to confirm which version sits in your garage before you open anything up. The job itself is well within reach of a rider with basic hand tools, a little patience, and a healthy respect for how unforgiving brake fluid is on paint.
How the Grom's Brake System Is Arranged
Up front, a single caliper grips a single disc, fed by a small reservoir built into the lever perch. At the rear, a second caliper and disc are fed by a remote reservoir mounted low on the right side of the bike, with a short hose running to the master cylinder. Each circuit is independent, which is good news: a mistake on one side does not contaminate the other, and you can bleed them one at a time without worrying about cross-feeding. If your Grom carries ABS, the pump and valve block sit inline in each circuit, and that is the one component a home bleed cannot always reach.
When a Bleed Is Actually Due
Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. That moisture lowers the fluid's boiling point, and a boiled fluid creates vapor that behaves exactly like air in the line — the lever goes soft right when you need it most. Even a Grom that lives a gentle life should get fresh fluid on a sensible interval, because the calendar does the damage, not the mileage.
Beyond routine refresh, bleed the system whenever the lever or pedal feels spongy, when the lever travels closer to the grip than it used to, when the fluid in either reservoir looks dark or cloudy, or after any work that opened the hydraulics: new lines, a caliper rebuild, or master cylinder service. A lever that firms up after a few quick pumps and then fades is a classic air-in-the-line symptom.
Tools and Supplies to Gather
- Fresh brake fluid of the type printed on the reservoir cap, from a sealed container — once a bottle is opened, it starts absorbing moisture, so use new stock
- A box-end wrench that fits the bleeder valve snugly
- Clear tubing sized to grip the bleeder tightly, plus a catch bottle
- Rags or shop towels, and a spray bottle of water for rinsing spills
- A syringe or turkey baster for pulling old fluid out of the reservoir
- 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 far less fiddly
Setting Up Before You Open Anything
Get the Grom upright and stable on a stand so it cannot tip while you are leaning over it. For the front circuit, turn the bars until the reservoir on the perch sits level — a tilted reservoir lets fluid spill the instant the cap comes off. Drape rags over the tank area, the plastics, the gauge cluster, and anything else below the reservoir, because brake fluid attacks paint and clear plastic on contact. If a drop lands anyway, wipe it up immediately and rinse the area with water rather than waiting until you finish.
The Bleeding Procedure, Step by Step
- Wipe the reservoir cap and surrounding area clean so grit cannot fall in, then remove the cap and diaphragm.
- 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.
- Top the reservoir up with fresh fluid from the sealed container.
- Push the clear tubing onto the bleeder valve and route the other end into the catch bottle, with the bottle positioned so you can watch the fluid come through.
- Squeeze the lever (or press the pedal) firmly and hold it. Do not release it yet.
- With the lever held, crack the bleeder about a quarter turn with the box-end wrench. Fluid and any trapped air will push out through the tube.
- Close the bleeder snugly before you let the lever return. Releasing first will suck air back past the threads.
- Check the reservoir level and top it off. Repeat the squeeze, hold, open, close, release cycle until the fluid arriving in the tube runs clean and free of bubbles.
- Keep an eye on the reservoir throughout. If it ever runs low enough to draw air at the master cylinder, you have just added the problem you were trying to remove and will need to start over.
- Move to the rear circuit and repeat the same sequence at the rear caliper bleeder, using the pedal instead of the lever.
If your bike has more than one caliper on a circuit, bleed them one at a time, and start with the caliper farthest from its master cylinder in terms of line length — that is where air tends to collect.
Finishing the Job Cleanly
Snug the bleeder down firmly with the box-end wrench, but do not lean on it; the valve is small and the caliper is not a place to demonstrate strength. 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 both the master cylinder and caliper for weeping or dampness. A dry paper towel pressed against each joint will show a leak you might miss by eye.
Testing Before You Ride Normally
Pull the lever and press the pedal. Both 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 at low speed, apply each brake separately and feel for proper, progressive response before you take the Grom into traffic.
When to Hand It to a Shop
If the lever will not firm up after several honest bleeding attempts, if it only firms after pumping, or if bubbles keep appearing no matter how long you work, stop and let a professional look at it. The same applies if fluid is leaking from the master cylinder or a caliper, or if your ABS-equipped Grom's reservoir ran dry or the ABS unit or its lines were disconnected — air trapped inside the ABS block generally needs a dealer-level procedure or diagnostic tool to purge, and that is not a job to improvise in a home garage.
Related Shopping Categories
Shop Brake Fluid for a 2019 Honda Grom Motorcycle.
Shop Brake Lines for a 2019 Honda Grom Motorcycle.
Shop Brake Pads for a 2019 Honda Grom Motorcycle.
Shop Stands for a 2019 Honda Grom Motorcycle.
Shop Brake Tools for a 2019 Honda Grom 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.
