Bleeding the brakes is a routine maintenance activity in any hydraulic brake system. Hydraulic brakes are the standard in today’s motorcycles, ATVs, UTVs, and cars, and the process is pretty similar for these machines. Here’s a how-to for your motorcycle, ATV or UTV from Honda Parts Direct. We ship nation-wide and internationally. We’ve also got a physical location in Palestine, Texas, serving Dallas and Houston, for in-store pick-up with no shipping cost. Check out our parts finder and online store for brake fluid and parts you need for pad replacements!
Why to Bleed Your Brakes
You’ll need to bleed the brakes under two circumstances. First, brake fluid gets very hot, so it wears out over time. It starts off clear and gradually darkens with use. Once it is darker than light amber, it should be replaced. Second, the fluid must be bled and replaced if it is contaminated by air or other foreign material. If this is the case, it’s also vital to investigate and resolve the cause of the contamination. Bleeding your brakes is a fairly simple process, but it should be done carefully so you don’t introduce any foreign matter into the system.
How Hydraulic Brakes Work
Very simply, a hydraulic brake system transfers pressure from the master cylinder to the brake caliper, via the brake fluid. Brake fluid can’t be compressed, but air can. That’s why your brakes feel squishy if there is air in the lines. You might also notice inconsistent or reduced braking power. If you notice such symptoms, inspect the entire system. Leaks can occur as a result of cracked lines, damaged seals, or loose banjo bolts. Fix any problems before bleeding the brakes. Before getting started, identify your brake calipers and the bleeder valve on top. Trace the path of the brake line to the master cylinder. There’s usually one in front and one in back.
Safety Measures
Brake fluid is high in solvents, so wear gloves and goggles. It can cloud plastics and strip paint, so protect your rig’s surfaces with rags. If you pump the brakes too fast while bleeding them, you may end up squirting the fluid. Always catch your retired brake fluid and dispose of it properly.
What You Need
Latex gloves and goggles
Correct brake fluid (see the text on the master cylinder cap or consult your service manual)
Screwdriver with the correct bit to remove the master cylinder lid (Phillips, JIS, hex, or other)
Wrench for bleeder valve (box or flat, usually 8mm)
About a foot of clear vinyl tubing (usually 5/16”)
Bottle for old brake fluid
Small plastic syringe
An assistant, or a spring clamp to keep the brake lever compressed
Consult Your Owner’s Manual
You should always review your factory service manual for specific information such as torque specs, detailed procedures, and fluid information. Many manuals are available online.
Open the Master Cylinder and Remove Diaphragm
Position your vehicle so the master cylinder you are working on is as level as possible. Clean the cover and surrounding area thoroughly, and drape protective rags around the cover before removing it. Extract the screw(s) carefully, using the correct bit so you don’t strip the threads. Lift the cap carefully - the diaphragm may come with it, and you don’t want to drop it and get it dirty. Remove the diaphragm. Set both parts aside in a safe, clean spot.
Place Tube on Bleeder Valve
Remove any covers or guards from the caliper, exposing the bleeder valve. Place your clear tubing over the bleeder valve nipple and place the other end into a catch bottle. Make sure the tube is snug on the bleeder valve, and completely covers the flared end.
Begin Bleeding Process
Have your assistant activate the brake, and open the bleed valve by a quarter to a half turn. Watch the fluid exit in the clear tube, noting whether it is discolored or includes air bubbles or other contaminants. Close the bleed valve, and release the brake slowly. Let it remain in its neutral, un-activated state for a few seconds, then repeat the process. Do this as many times as necessary to eliminate the old fluid, air bubbles, and other contaminants from the system. Keep an eye on the fluid level in the master cylinder and top it off as necessary - you don’t want any air sucked into the system. A small plastic syringe is ideal for topping off the fluid. When nothing but clear brake fluid is exiting the bleed valve, you’re done.
Top Off and Reassemble
Top off the fluid in the master cylinder to the upper level of the fill line. Carefully replace the diaphragm and the cover, along with any remaining hardware. Close the bleeder valve tightly and remove the tube.
Test Brakes
Test the brakes while rolling the machine back and forth in neutral. If the brakes seem suitably responsive, take it for a test ride. Start slowly, gradually testing greater speed and braking load as you go. Do this in a safe, controlled place in case something goes wrong. If you feel confident in the braking power, get off the machine and check the master cylinder, line and caliper one more time to verify there are no leaks. Take one more test drive and you should be good to go!
Honda Parts Direct has the parts you need to keep your wheels rolling! We want to help you feel confident about how to bleed your ATV brakes or how to bleed your motorcycle brakes. We're a family-owned and family-operated company, and we’ve been serving the East Texas area with genuine Honda® parts and accessories for 30 years. We ship worldwide, and we also welcome you to our physical location in Palestine, Texas, serving Dallas and Houston, for in-store pick-up for absolutely no shipping cost.