Bleeding the Brakes on Your 2020 Honda Grom

Shop parts for a 2020 Honda Grom Motorcycle.

First, Understand the System You're Bleeding

The 2020 Honda Grom stops on hydraulic disc brakes at both ends, and the two ends are completely independent of each other. The lever on the right handlebar pushes fluid from a small master cylinder mounted at the bar down to the front caliper. The pedal at the right footpeg works a separate master cylinder and reservoir that feeds the rear caliper. Nothing connects the two circuits, which means a soft front lever tells you nothing about the condition of the rear brake, and vice versa. Each side gets its own bleed, its own fluid top-off, and its own final check.

Honda sold the 2020 Grom in both ABS and non-ABS forms depending on market and trim, so confirm which one is in your garage before you start. An amber ABS indicator that illuminates at key-on and then goes out is the quickest tell, and a toothed ring with a small sensor at either wheel confirms it. On a non-ABS Grom, the job is as straightforward as brake work gets. On an ABS-equipped bike, a routine fluid refresh through the caliper bleeders is still the same basic procedure, but the hydraulic modulator is a different story — if air has reached it, the unit generally needs to be cycled with a dealer-level tool, and that is not a home-garage job.

The Grom does not use a linked or combined braking system, so there is no crossover valve, no extra bleed point, and no special sequence to follow. Front and rear are handled one at a time, in whatever order you prefer.

Signs It's Time — and What Old Fluid Does

Bleeding covers two related jobs: pushing air out of the hydraulics and replacing tired fluid with fresh. Air shows up as a lever or pedal that feels spongy, vague, or that pulls noticeably closer to the grip than it used to. Fluid that has gone dark, cloudy, or gritty-looking in the reservoir is past its useful life. Any repair that opened the system — new lines, a caliper rebuild, master cylinder work, or a reservoir that ran dry — means air is in there and a bleed is mandatory before the bike moves again.

Even with no symptoms, brake fluid absorbs moisture from the air over time. That moisture lowers the fluid's boiling point, and under hard or repeated braking the fluid can boil and create gas in the lines, which shows up as a lever that goes long or soft exactly when you need it most. That is why many riders refresh the fluid on a regular interval rather than waiting for a problem to announce itself.

Tools and Supplies to Have Ready

  • Fresh brake fluid of the type printed on your bike's master cylinder reservoir cap, from a sealed container. Do not substitute a different type.
  • A box-end wrench that fits the bleeder valve snugly — a loose fit will round the hex.
  • A length of clear tubing that slips over the bleeder nipple without leaking air past it.
  • A small catch bottle to hang the tubing into.
  • Rags or shop towels, plus a syringe or turkey baster for pulling old fluid out of the reservoir.
  • The correct driver for the reservoir cap screws.
  • Optional but helpful for solo work: a one-way check-valve bleeder or a vacuum bleeder.

Setting Up Safely

Get the Grom upright and stable on a stand so it cannot tip while you are leaning on the lever. For the front, turn the handlebars until the reservoir on the bar sits level; a tilted reservoir will spill fluid the moment the cap comes off. Lay rags over the tank area, the plastics, the instrument cluster, and anything else below the reservoir, because brake fluid attacks paint and many plastics on contact. If a drop lands where it shouldn't, wipe it up immediately and rinse the area with water rather than waiting until you finish.

The Bleeding Procedure, Step by Step

  1. Wipe the reservoir cap and surrounding area clean so grit cannot fall in, then remove the cap and the diaphragm beneath it.
  2. Use the syringe or baster to draw most of the old fluid out of the reservoir. Leave enough to cover the bottom so you do not push air into the master cylinder.
  3. Refill with fresh fluid from the sealed container, and keep the container capped between pours.
  4. Push the clear tubing onto the bleeder valve and route the other end into the catch bottle, with the bottle positioned so the tubing runs uphill or level rather than straight down into a puddle.
  5. Fit the box-end wrench onto the bleeder, then squeeze the front lever (or press the rear pedal) and hold it firmly.
  6. With the lever or pedal held, crack the bleeder about a quarter turn. Fluid and any trapped air will push out through the tubing.
  7. Close the bleeder before you release the lever or pedal. Releasing first draws air back in through the open valve — this is the single most common mistake in the whole job.
  8. Release the lever or pedal slowly, then repeat the squeeze–hold–open–close–release cycle. Watch the tubing: you are looking for a steady stream with no bubbles, and a color that matches the fresh fluid going in.
  9. Check the reservoir every few cycles and top it off. If it ever runs low enough to draw air at the master cylinder, you have added air upstream and will need to keep bleeding until it clears.
  10. When the fluid runs clean and bubble-free, close the bleeder, top the reservoir to the level marking, and repeat the entire process on the other brake circuit.

If your bike has more than one front caliper, bleed each one separately, finishing with the caliper farthest from the master cylinder first and working toward the closest.

Finishing the Job

Tighten the bleeder snugly with the box-end wrench — firm enough to seal, never so tight that you crush the seat or stretch the threads. Reinstall the diaphragm and cap, wipe down every surface you touched, and inspect the bleeder and the banjo fittings at the caliper and master cylinder for weeping. A dry paper towel held against each joint for a moment will show a leak that a visual check misses.

Verify Before You Ride

The lever and pedal should feel firm and consistent, and should hold pressure without slowly sinking while you hold steady force on them. Spin each wheel by hand to confirm the brake is not dragging. Then, in a safe open area, test at walking pace and gradually build speed, feeling for a solid, predictable bite. If anything feels vague, stop and re-bleed rather than riding it out.

When to Hand It to a Shop

If the lever will not firm up after several full bleeding cycles, if it only firms after pumping, if bubbles keep appearing no matter how long you bleed, or if you find fluid weeping from the master cylinder or caliper, stop and have the system inspected. The same applies to any ABS-equipped Grom where the reservoir ran dry or a line or the modulator was disconnected — that air needs a dealer-level procedure to clear properly.

Related Shopping Categories

Shop Brake Fluid for a 2020 Honda Grom Motorcycle.

Shop Brake Lines for a 2020 Honda Grom Motorcycle.

Shop Brake Pads for a 2020 Honda Grom Motorcycle.

Shop Stands for a 2020 Honda Grom Motorcycle.

Shop Brake Tools for a 2020 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.