Why Are My Honda CBR600 Brakes Spongy After Bleeding?

What happens if you recently bled the brakes on your Honda motorcycle, but they still feel spongy afterward? If you see air bubbles in the brake fluid, did you really bleed the brakes properly?

Partzilla’s Honda motorcycle expert John Talley does live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this edition, John was asked for advice on what to do about spongy front brakes on a 2007 Honda CBR600 motorcycle after a brake bleeding.

Honda CBR600 brake bleeding

Honda Motorcycle Brakes Spongy After Bleeding

Every four or five days, my 07 Honda CBR600 front brake becomes noticeably spongy after what I feel is a really strong, good bleeding, with air bubbles coming from the upper bleeding port near the reservoir. No leaks identified. This is a big mystery for me. Could you give me some hints?

John Talley: Well, when you say you did a good bleeding, does that mean you just bled it out a little bit? It sounds like your machine, especially an 07, is getting a little long in the tooth, so when’s the last time you actually flushed out the entire front brakes? Or the entire front braking system, I should say. You might as well do the rear brakes as well. The reason is that the brake fluid is what they call hygroscopic, and it actually attracts water. Chances are after this much time, there’s probably some water in that fluid, intermixing with it. So you go and you bleed it and that gets rid of most of it, but not all of it, and it kind of builds up again. And of course it’s going to heat up fast compared to the fluid and cause the problem that you’re talking about. So my advice to you would be to go through and completely flush it out. Because chances are it’s definitely past time to do that, then start with new fluid all the way from the top to the bottom, and then bleed it again.