Bleeding the brakes on your motorcycle is not something you’ll have to do often, but it’s a useful thing to be able to do. Understanding basic motorcycle maintenance can save you a lot of time and money. Many newer riders or those new to mechanical maintenance wonder how to bleed motorcycle brakes.
The 6 easy steps to bleed your motorcycle brakes are:
- Prepare your tools and materials
- Set up the bike for bleeding
- Bleed the brakes
- Fill the fluid and seal the system
- Store leftover brake fluid
As well as precise instructions on bleeding motorcycle brakes, you may also want to know how often to do it and why you need to bleed them in the first place. There are also some common issues that occur while bleeding motorcycle brakes. Read on, as I’ll cover all of this and more below.
Bleeding your brakes means to replace your old brake fluid with new fluid. This process is necessary in motorcycles with hydraulic brakes to keep them functioning correctly. By opening a valve, you can remove old fluid and then replace it with new. This keeps your brakes working properly.
Hydraulic Brakes In A Nutshell
So, when you pull/push your brake lever or pedal, a few things are happening. The act of pulling the lever engages a hydraulic piston. This piston compresses some very viscous hydraulic fluid, this now pressurized fluid engages another separate piston on your brake assembly itself.
This piston compresses pads around a disc (unless you have drum brakes, which is less common these days). Motorcycle brake pads are made of a high friction material, and the act of them clamping down hard on the metal disc creates friction, and slows the motorcycle down.
Now, the key element that makes this system work is the brake fluid. This fluid is what allows pressure to travel instantly and evenly to the piston that your brakes need to work properly. It would stand to reason that this fluid needs to be in good shape for the brakes to work optimally.
If the fluid needs to be replaced, you have to bleed it out of the system. This replacement involves flushing the old fluid out of the system while introducing new and fresh fluid. The process of doing this is known as bleeding your brakes.
You bleed your brakes by pressurizing the system and opening a bleeder valve. You let the old fluid come out, close the valve, add new fluid, and keep on flushing the system. Slowly but surely, the old fluid goes out and the new fluid goes in.
You should bleed your motorcycle brakes to ensure they continue to work properly. Brake fluid deteriorates over time, and you need to replace it with new fluid so braking performance doesn’t decline. If you’re having braking issues or installing new brake parts, you’ll need to bleed your brakes.
Like any fluid within your motorcycle, brake fluid will deteriorate with use and over time. Even if your brakes are perfectly functioning, eventually the fluid will get old, and it will stop being as effective. If brake fluid gets too old or dirty it will stop working as well and could even start to impair braking components.
Obviously, keeping your brake components functioning as well as possible is very important when it comes to motorcycle safety. So, if the fluid in your brake system hasn’t been changed for long enough, it should be bled and replaced.
Another reason to bleed your brakes is if they seem to be not functioning as well as they should. Most motorcycle brakes, especially on modern bikes, should have quite a lot of stopping power. If the brakes feel unpredictable or like a lot of force is required to use them, there’s probably something wrong.
Changing brake fluid can make a huge improvement in the feel of a motorcycle’s brakes. Sometimes a motorcycle may have old or dirty fluid, sometimes it may even have air in the system. Brakes don’t always get bled correctly, and any lingering air in the system will hugely compromise braking ability.
The other reason to bleed your brakes is if you’re changing brake parts. This one isn’t always going to be necessary, but it’s often a good idea anyway.
Usually when you change parts such as brake pads, you’ll have to force the caliper piston more open than it was before changing the parts. As brake pads wear down, the amount of fluid required in the system increases. The piston has to push further and further out in order to make the pads contact the disc.
Brand new brake pads will require less fluid in the system, so installing them may overflow the brake master cylinder if your fluid is at the right level before changing the parts. Now, you could always just remove fluid from the master cylinder, but if you’re already messing around with brake fluid, it’s worth just bleeding the system.
This may not seem like the best reason, but in some cases, trusting what you see is really a good idea. Especially if you’ve recently purchased a used bike, you don’t always know when the brake fluid was last changed.
Brake fluid should look pretty clear and not too murky, and definitely free of any debris. It should more or less look like new brake fluid. If it looks murky or dirty or has debris in it, chances are it’s time for it to be changed.
You’ll need a few different things to bleed your brakes. You’ll need a small wrench that will fit on your bleeder valve screw. Make sure it’s a good fit, as you’ll be moving it around a lot. You’ll also need a small container to bleed your fluid into and a tube that will fit around (and stay on) your bleeder valve screw.
You’ll also need a container of fresh brake fluid. Make sure to get the right brake fluid for your bike, as there are different types. Usually, the bike will have the correct brake fluid to use listed on the master cylinder cap, but if it doesn’t, looking online usually works.
Beyond that, having some rags or paper towels ready to wipe up spills is very useful. This job is much easier to do if you have someone to help you, although you can usually do it by yourself.
Remove the rubber nipple on the end of the bleeder valve screw. Put your small wrench on it and then push the tube on top of the hole. Place the other end of the tube at the bottom of your small container. If you happen to have an old container of brake fluid that’s even better.
The goal is to avoid accidentally putting any air back into the brake system while bleeding it. Remove the cap on the master cylinder and get your fresh bottle of brake fluid ready, you’ll be adding it to the master cylinder little by little.
Squeeze the brake lever (or push the pedal if you’re doing rear brakes). While keeping pressure on the lever, loosen the bleeder valve screw with the wrench. You should feel all the pressure leave the system and see brake fluid go through the tube.
Tighten the bleeder valve screw and return the lever to its normal position. Add fluid if necessary (keeping the master cylinder reservoir full) and repeat this process. Keep doing this until the fluid coming out of the tube looks like the fluid you’re putting in the master cylinder.
When you close the bleeder valve the final time, check the feel of the brake lever. It should feel firm and difficult to pull. If it does not, your bleeder valve may not be fully closed, or you may have air in the system.
Fill the master cylinder reservoir up to the recommended level. Replace the cap and tighten. A brake system should be well sealed, brake fluid doesn’t perform as well if there are leaks, even if they’re at the top of the system.
Check again to ensure the bleeder valve screw is tight. Careful not to overtighten, as it’s usually a steel screw going into aluminum, so stripping the threads is a real danger.Re-install the rubber nipple bleeder valve cap.
If you’ve made it this far, you’ve successfully bled your brakes. Congratulations! Now that your brakes are bled and the system is sealed, it’s time to clean up your work area.This can sometimes be a messy job and brake fluid is highly destructive on the wrong surfaces.
Brake fluid can destroy paint and other such things, so make sure there isn’t any excess fluid on your bike. Use the rags or paper towels to wipe everything off and ensure your bike is clean.
Your old brake fluid should be transferred to a sealable container and disposed of like any other chemical. Many local waste dumps may have places for it, some areas also have chemical reclamation days. Either way, make sure you dispose of it properly.
6. Store Leftover Brake Fluid
If you have any new brake fluid left over seal it up again and write the date you opened it on the cap or bottle. For a little while it will still be usable for your bike or any other vehicle. Most manufacturers say a previously opened container of brake fluid is good for about a year after opening.
Theoretically, the fluid you store should last just as long as the brake fluid you just put in your bike, as they were both opened on the same date. This assumes it’s being stored in a good container without too much air leakage. Just be sure to remember that the longer you wait to use the fluid, the shorter its service life will be.
You should bleed your motorcycle brakes about once every two years. If you ride a lot, you may want to increase how often you bleed them. As brake fluid is heated and cooled consistently while riding, if you ride a lot, it will be likely break down more quickly.
Even if you don’t ride a lot, changing your fluid is still important as it will oxidize and become dirty over time regardless of how much you ride. That said, 2 years is just the recommended interval, if you don’t ride much you may be able to get away with more than that.
The main thing to remember is that bleeding your brakes isn’t a piece of maintenance that should be put off indefinitely. Brakes are very important and keeping them maintained keeps them working properly.
You can bleed motorcycle brakes with ABS systems exactly the same way that you would if they didn’t have ABS. All ABS systems are different, so this isn’t true for all motorcycles with ABS. But in general, there is no difference in method for bleeding brakes with or without anti-lock brakes.
This is an area where consulting your manual is a good idea. If your bike didn’t come with a manual, or the manual it came with doesn’t discuss brake bleeding, try finding a shop manual online. You may be surprised how many free PDFs are floating around out there on the internet.
You can also try searching for brake bleeding procedures on your particular bike. Especially for more common bikes, the chances are high that you may find forum results or even video tutorials for exactly your bike that may show any differences in procedure from the average bike.
Common Motorcycle Brake Bleeding Problems
This is the most common problem while bleeding brakes. Don’t stress about it, just wipe up any spills, and if some soaks into your garage or driveway, a decent solvent (brake cleaner for example) should get it out.
Another problem people sometimes run into is stripping out their bleeder valve screw threads. As I mentioned earlier, the bleeder valve screw is usually a steel screw that screws into aluminum. This is a recipe for stripped threads, as usually steel is much stronger, so the steel screw can overpower the aluminum very easily.
Remember, it just needs to be tight, not incredibly torqued down. In general, the size of a screw, bolt, or nut roughly corresponds to the level of tightness it needs to be at. Bleeder valve screws are pretty small, so they don’t need a lot of torque.
Sometimes people may also deal with stripped heads on the same bleeder valve screws. Especially if the brake fluid hasn’t been flushed in a while, or flushed ever, these screws can sometimes be really stuck in there.
Usually, a few taps with a light hammer on the wrench will break the screw loose. You could also try using a breaker bar. If those methods don’t work and the head begins to strip, I usually recommend vice grips. Just know that they can destroy the screw head, so use them with caution or be prepared to replace the bleeder valve screw.
Bleeding your motorcycle brakes may not be something that everyone wants to do. It can certainly be a dirty job, and you’ll have to deal with brake fluid, which is not the nicest substance. That said, I think it’s something anyone with a couple of tools and a positive attitude can easily learn how to do.