How To Flush and Bleed Your Motorcycle Brakes | The Shop Manual

Introduction

This tutorial will guide you through the process of flushing and bleeding your motorcycle brakes, a crucial maintenance task that can enhance brake performance and safety. Regular maintenance, including replacing brake fluid every two years, helps prevent spongy brakes and ensures your motorcycle stops effectively.

Step 1: Gather Your Supplies

Before starting, you need the following materials:

• 3/16 inch ID vinyl hose (available at hardware stores)
• A wrench (to fit the bleeder valve)
• Screwdriver (for the reservoir cap)
• Brake fluid (typically DOT-4)
• A receptacle for old fluid (like a sealable jug)
• Paper towels and rags to clean up spills

Practical Tips

• Ensure you have more hose than you think you'll need to properly manage fluid flow.
• Use a sealable container for easy disposal of old brake fluid.

Step 2: Prepare the Work Area

• Protect your motorcycle's paint by placing paper towels around the master cylinder and other components where spills may occur.
• Identify the bleeder valve on the caliper you will work on first (start with the farthest caliper from the master cylinder).

Step 3: Remove the Dust Cover and Attach the Hose

• Take off the dust cover from the bleeder valve.
• Attach the vinyl hose securely to the bleeder valve; it should fit snugly to prevent leaks.

Common Pitfalls

• Avoid using the open end of the wrench to prevent it from slipping off the bleeder valve.

Step 4: Check and Prepare the Master Cylinder

• Use a screwdriver to remove the master cylinder reservoir cap (be aware it may be a JIS screw if you have a Japanese bike).
• Check the fluid level inside the reservoir and top it off if necessary.

Practical Advice

• Keep the cap on while bleeding to prevent fluid from spraying out during the process.

Step 5: Bleed the Brakes

1. Pull the brake lever to pressurize the system.
2. Open the bleeder valve about a quarter turn while holding the lever in.
3. Watch for fluid and air bubbles escaping through the hose.
4. Close the bleeder valve before releasing the brake lever.
5. Repeat this process until you see a steady stream of fluid without bubbles.

Hot Tips

• If the old fluid looks dark and contaminated, consider using a syringe or turkey baster to remove it before starting the bleeding process.
• Always monitor the reservoir to ensure it doesn’t run dry, as this will introduce air into the system.

Step 6: Repeat for Other Calipers

• Move to the next caliper and repeat the bleeding process.
• For dual disc brakes, always start from the farthest caliper and work towards the master cylinder.

Step 7: Final Checks and Cleanup

• Once all calipers are bled, check the master cylinder reservoir one last time to ensure it's full.
• Reattach the reservoir cap and tighten the screws.
• Clean any spilled brake fluid from the calipers and surrounding areas with a damp rag.

Conclusion

You've successfully flushed and bled your motorcycle brakes, improving their responsiveness and safety. Regularly check and maintain brake fluid levels and consider repeating this process every two years. If you're unsure about any steps, consulting a professional mechanic is always a good idea. Happy riding!