I’m in dire need of some advice. I’ve been struggling to bleed the master cylinder on my motorcycle, and it’s driving me nuts. The brake lever feels spongy, and I’m not getting the response I need. Has anyone cracked the code on this? I could really use some step-by-step guidance or any tips you might have.
Response
What did the trick for me was the bench bleeding method, specifically using my thumb over the banjo hole. It’s a bit of a hassle, but trust me, it’s worth it for the improved brake feel. Give it a shot and see how it goes!
Solutions that Worked for Users
| Solution | Users Who Found Success | Approx. Cost (USD) | Time Needed (Minutes) |
|---|---|---|---|
| Bench Bleeding with Thumb Over Banjo Hole | 5 | $0 (DIY) | 30 |
| Filling from the Bottom via Caliper Bleeder Nipple | 3 | $5 (for syringe and tube) | 20 |
| Using an Orbital Sander for Vibration | 2 | $0 (if you already have the sander) | 15 |
| Vacuum Bleeding with Teflon Tape and Tiewrap | 2 | $10 (for materials) | 25 |
Symptoms
- Spongy or unresponsive brake lever.
- Ineffective braking despite multiple bleed attempts.
- Persistent air bubbles in the brake fluid.
Possible Causes
- Air trapped in the master cylinder or brake lines.
- Ineffective bleeding techniques.
- Complications due to hardware changes or maintenance.
Solutions that Worked
Bench Bleeding with Thumb Over Banjo Hole
- What I Did: Removed the banjo bolt, covered the hole with my thumb, and gently pumped the lever.
- Outcome: Successfully removed air bubbles, resulting in a firmer brake lever.
- Personal Experience: A bit messy but incredibly effective.
- Steps:
- Preparation: Gather a clean rag, gloves, and brake fluid.
- Banjo Bolt Removal: Carefully remove the banjo bolt from the master cylinder.
- Thumb Placement: Place your thumb over the hole to create a seal.
- Pumping: Gently pump the brake lever several times. You should feel pressure building.
- Observation: Release your thumb slightly between pumps to allow air and fluid to escape.
- Repeat: Continue this process until no more air bubbles come out.
- Clean Up: Wipe away any spilled fluid and reattach the banjo bolt.
- Expert Tip: Make sure the brake fluid reservoir is topped up during this process to avoid introducing more air.
- Handy Tip: Use a piece of clear tubing over the hole to direct the fluid into a container, minimizing mess.
Filling from the Bottom via Caliper Bleeder Nipple
- What I Did: Used a syringe to fill the system from the bottom.
- Outcome: Effective in filling empty lines and removing air pockets.
- Personal Experience: Unconventional but surprisingly effective.
- Steps:
- Syringe Preparation: Fill a clean syringe with fresh brake fluid.
- Connection: Attach a piece of tubing from the syringe to the caliper bleeder nipple.
- Injection: Slowly inject fluid into the system, watching for air bubbles in the reservoir.
- Monitoring: Continue until the reservoir is full and no more air bubbles are visible.
- Conventional Bleeding: Follow up with a standard bleeding process to ensure all air is out.
- Expert Tip: Keep the master cylinder reservoir cap loose to allow air to escape.
- Unique Info: This method is particularly effective for systems that have been drained or after line replacements.
Using an Orbital Sander for Vibration
- What I Did: Applied vibration to the calipers and brake lines using an orbital sander.
- Outcome: Helped move stubborn air bubbles upwards.
- Personal Experience: Seemed odd at first, but the vibrations really did the trick.
- Steps:
- Sander Preparation: Secure an orbital sander (without sandpaper) to the caliper.
- Vibration Application: Turn on the sander to create vibrations along the brake lines.
- Observation: Watch for air bubbles rising in the reservoir.
- Additional Bleeding: Continue with conventional bleeding if necessary.
- Expert Tip: Focus the vibrations on areas where air bubbles are likely to be trapped, like bends in the lines.
- Handy Tip: If you don’t have an orbital sander, tapping the lines and calipers with a rubber mallet can also help.
Vacuum Bleeding with Teflon Tape and Tiewrap
- What I Did: Used Teflon tape and a tiewrap to enhance the vacuum bleeding process.
- Outcome: More effective vacuum bleeding with less air intake.
- Personal Experience: A simple tweak that made a big difference.
- Steps:
- Teflon Tape Application: Wrap Teflon tape around the bleeding nipple threads.
- Hose Securing: Use a tiewrap to secure the vacuum hose to the nipple.
- Vacuum Bleeding: Proceed with vacuum bleeding, ensuring a tight seal.
- Monitoring: Watch for a steady stream of fluid without air bubbles.
- Expert Tip: Check for any leaks in the vacuum setup before starting to ensure efficiency.
- Unique Info: This method can significantly reduce the time and effort needed for bleeding, especially on stubborn systems.
Motorcycle Models Where This Worked
- Various models and years, as these techniques are generally applicable across different motorcycles.