Bleeding the Brakes on a 1999 Honda ST1100 ABS
Shop parts for a 1999 Honda ST1100 ABS Motorcycle.
What You Are Working On
The 1999 Honda ST1100 ABS uses hydraulic disc brakes at both ends, and the anti-lock system adds a hydraulic modulator and extra lines to the circuit. That means this job covers two separate systems: the front brake, fed by the master cylinder on the handlebar, and the rear brake, fed by its own master cylinder and pedal. Each has to be bled on its own, with its own reservoir kept full throughout. The good news is that a routine fluid refresh and air purge happens at the caliper bleeders, exactly as it would on a non-ABS bike. The ABS unit only becomes a complication if air has actually traveled into it.
Before you start, confirm what your particular bike is carrying. Some ST1100 variants in this era used additional bleed points or a linked arrangement between the front and rear circuits. If your bike has more than one bleeder per caliper or extra bleed fittings along the lines, the order in which you open them matters, and getting it wrong can leave air trapped. If you are not certain of the layout on your machine, have a shop handle the flush rather than experimenting.
Signs the System Is Due for Fresh Fluid
Brake fluid is hygroscopic, meaning it pulls moisture out of the air over time. Moisture lowers the fluid's boiling point, and a fluid that boils under hard braking produces vapor that behaves exactly like air in the lines — the lever goes soft right when you need it most. That is why many riders refresh the fluid on a schedule even when nothing feels wrong.
Bleed the brakes if the lever or pedal feels spongy, if the lever now travels closer to the grip than it used to, or if the fluid in the reservoir looks dark, cloudy, or gritty. You should also bleed after any work that opened the hydraulic system: new lines, caliper service, master cylinder work, or a reservoir that ran dry. A lever that only firms up after several quick pumps is a classic sign that air is present.
Tools & 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 valve snugly
- Clear tubing sized to fit tightly over the bleeder nipple
- A clear catch bottle with a little fluid in the bottom
- Rags or shop towels, plus a syringe or turkey baster
- The correct driver for the reservoir cap screws
- Optional: a one-way check-valve bleeder or a vacuum bleeder, which makes a solo job much easier
Clear tubing is worth insisting on. Being able to see the fluid and the bubbles is how you know when the job is finished.
Setting Up Before You Open Anything
Get the bike securely upright on a stand on level ground. Turn the handlebars so the front reservoir sits level; a tilted reservoir spills fluid the moment the cap comes off. Drape rags over the tank or bodywork, the instrument area, and anything painted or plastic near the reservoirs and calipers. Brake fluid attacks paint and plastic on contact, so wipe up any drip immediately and rinse the area with water if a spill does happen.
Work the front system first, then the rear, and keep the bike from being disturbed while a reservoir is open.
The Bleeding Procedure, Step by Step
- Clean the reservoir cap and surrounding area so grit cannot fall in, then remove the cap and lift out the diaphragm.
- Draw most of the old fluid out of the reservoir with the syringe, stopping before the bottom so you do not push air into the line.
- Refill with fresh fluid from the sealed container, leaving the reservoir comfortably full.
- Push the clear tubing onto the bleeder valve and route the other end into the catch bottle, keeping that end submerged in fluid.
- Fit the box-end wrench over the bleeder.
- Squeeze the front lever and hold it steady, or press and hold the rear pedal when you move to that circuit.
- Open the bleeder about a quarter turn and watch the tube. Fluid and any trapped air will push out.
- Close the bleeder before you release the lever or pedal. Releasing with the bleeder open draws air straight back into the caliper.
- Repeat the squeeze, open, close, release cycle, topping off the reservoir every few strokes so it never drops low enough to pull air in.
- Continue until the fluid coming through the tube runs clean and completely free of bubbles. If your bike has two front calipers, bleed each one in turn. As a general practice, start with the caliper farthest from the master cylinder.
- Move to the rear circuit and repeat the same sequence using the pedal and the rear bleeder. On this bike the rear reservoir may be remote from the master cylinder, so check its level just as carefully.
Finishing the Job
Close the bleeder snugly with the wrench — firm enough to seal, but not so hard that you deform the valve or the caliper boss. Pull the tubing off and wipe the area clean. Fill the reservoir to the level marking on the body, reinstall the diaphragm so it seats flat, and refit the cap and screws. Rinse away any fluid that touched paint or plastic, then look over the bleeder and the banjo fittings at the caliper and master cylinder for weeping or wetness.
Testing Before You Ride
Pull the lever and press the pedal. Both should feel firm and consistent, and neither should slowly sink while you hold steady pressure on it. Spin each wheel by hand and confirm the brakes are not dragging. Then find a safe, empty area and test the brakes at low speed before riding normally. If anything feels vague or long, stop and bleed again.
When to Hand It to a Shop
If the lever will not firm up after several honest attempts, if it only firms up after pumping, or if bubbles keep appearing no matter how long you bleed, something is admitting air — a tired master cylinder seal, a loose fitting, or a line that needs attention. Leaks at the master cylinder or caliper belong in the same category. Most importantly, if the reservoir ran dry, or the ABS unit or its lines were disconnected or replaced, air may now be inside the modulator, and that requires a dealer-level procedure or diagnostic tool. On a bike with extra or linked bleed points, follow the correct sequence or let a professional do it. Brakes are not the place to guess.
Related Shopping Categories
Shop Brake Fluid for a 1999 Honda ST1100 ABS Motorcycle.
Shop Brake Lines for a 1999 Honda ST1100 ABS Motorcycle.
Shop Brake Pads for a 1999 Honda ST1100 ABS Motorcycle.
Shop Stands for a 1999 Honda ST1100 ABS Motorcycle.
Shop Brake Tools for a 1999 Honda ST1100 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.
