Thursday, November 12, 2009

Let It Bleed

Over the past week or so, my rear brake had lost about 80% of its stopping power. The brake handle was touching the handlebar, and barely slowing the bike down, at all. I was assuming the rear pads needed replacing, but perhaps not just yet.

I asked around online, and the Yahoo! Kymco forum provided a possible answer: There's air in them-thar brake lines! How does it get in there? I dunno, but NOW, thanks to Josh @ ESS, I discovered how easy it is to bleed one's own brakes with no assistance.
  1. Open the master cylinder cap. Keep it clean! If it's dirty, clean it up before you open it -- you don't want dirt getting inside the brake circuit.
  2. Pump the brake handle 10-20 times.
  3. Using an 8mm box or open-ended wrench, SLOWLY open the bleeder valve on top of the brake caliper to let fluid and any air escape, being sure NOT to suck air back into the bleeder valve.
  4. Re-tighten bleeder valve.
  5. Repeat steps 2-4 several times, adding fluid at the master cylinder as needed, only stopping when no air bubbles are present in the fluid leaving the bleeder valve.
  6. Replace clean master cylinder cap and tighten its screws.
Now, your life should be complete. :) Live long, and prosper.


  1. I hate telling "Told you so", but... Told you so! :)

  2. Don't forget to tie the brake lever down after you pump it. If you leave it open, the system is open and you'll have no pressure to pump out the air and bad fluid. Untie it only after closing the bleeder valve.