I have been changing the brake fluid on my motorcycles for over 40 years. I like to do it about every two years, as recommended by most mechanics and service manuals. Recently I tried replacing the brake fluid on my non-ABS, single front disc braked, 2009 BMW F650GS (the 800cc twin). The rear brake was a snap, but I ran into trouble with the front brake. I was using a one-way valve EZ brake bleeder type device and must have accidentally introduced some air into the system. The lever dropped to the handlebar grip without much resistance when squeezed. After a while using the bleeder and running fluid through the system, it wasn’t getting any better. I then switched to my vacuum pump bleeder and was able to get more feel to the lever, but it still was mushy. I then resorted to the old-school method of bleeding manually by slowly squeezing the lever, while opening the caliper bleeder and then closing it before the lever hit the grip. That didn’t make much of an improvement in the lever’s feel, either. I rode the bike around and while it braked OK, the lever still had a spongy feel and it would almost hit the grip when braking hard. Not good, but I was running out of ideas and decided to give up for the day.
Later that afternoon I recalled that sometimes it has been reported that if you strapped the lever as tight as possible to the grip overnight, it would help expel the air in the system. Not having any better ideas, I placed the bike on the side stand and turned the bars to the left, which placed the master cylinder at its highest point relative to the caliper. I then tied the brake lever to the grip using a Velcro-covered strap. I left the bike like this overnight. The next morning I loosened the strap and - "Eureka"! I found that all of the air had been expelled from the system, the brake lever feel was hard and firm and the lever would stop a good distance from the bar. What a difference. In fact, it now has better feel than when it came from the factory. So that is my tip for today. If you ever have a problem getting a solid feel from your brake lever and other methods fail, give this fluid bleeding method a try. It is easy and seems to work.
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Topic: Bleeding Brake Lines Tip (Read 1521 times)