125-200cc Brake bleed technique

I'm filling the front brake system up from dry, and having trouble getting the brake to pressure up. There's nothing - only enough to move the oil through when bleeding. I've tried filling it from the caliper upwards and from the top down. I've bled a whole load of fresh oil through the system and it's coming through without bubbles - so I'm guessing there's air in the master cylinder that won't shift. Any thoughts? Thanks...

How are you bleeding it? You should be able to bleed master cylinder and then the caliper. You should be able to just squeeze front brake and while holding tight open up screw let some come out and then close screw and let go. You can also do this on master cylinder with banjo bolt. Its always worked for me but sometimes just takes time

First I pumped fluid up from caliper using tube and cycle pump (low pressure) until it ran out of master cylinder res. Then I started the bleeding by pumping lever and fluid down from master and opening and releasing valve on calliper. If there's an airlock at the top in the master that's not coming down through the line, how do I get at it?

Check you banjo bolts, I had the same problem after changing my front brake line. Would get fluid through but not build pressure, tightened both banjo bolts a tad more and fixed it. For some reason they suck air before the let fluid out.

What has worked for me in the past has been to remove the master cylinder/lever assembly from the bars and place near the ground (lower than the slave cylinder) that way the air bubbles are traveling upwards when you pump the brake lever.

The front brake on my bike is easily the worst thing I've ever had to bleed. I find I need to use a combo of back bleeding (big ol' syringe on the bleeder pushing fluid in), vacuum bleeding (vac pump on the bleeder), and pumping the lever by hand.


I had one time I was into this thing for like an hour with absolutely no pressure at all and was getting pissed, so I just let it sit and worked on another bike. Came back 3-4 hours later and had a perfect lever

Thanks. I'm psyching myself up for another crack at it tonight.

No guarantee this will work, but it would work on my friends' road race bikes when we had trouble bleeding them. Pull the lever in and use a cable tie to keep it tight to the grip. Let it sit overnight, cut the cable tie, but let the lever out slow. Don't pull it in for 15 minutes or so.

That method worked on my husaberg. It always had a spongy lever after standard bleeding procedures.

Thanks for the tip - this seems to have worked - definitely got a decent bite on it now. I used this in combination with back bleeding up the line from the caliper.