bleeding front brakes.

i have replaced the front caliper on a 06 250 yz and i cannot get the brakes to pump up, i have tried pumping brake fluid through the system . also regular method. starting to think master cylinder may be bypassing any ideas

thanks

Do you have any kind of syringe? If so, you can pump or pull brake fluid through the bleeder valve. This should make it easier to get to where you can bleed the system.

The lever goes straight to the bar with no resistance? Crack the bleeder on the caliper and take the cap off the MC and let it drip for awhile then close the bleeder. If you squeeze the lever and crack the bleeder does fluid squirt out? Take the MC apart and give it a good cleaning and rebuild it if you can get your hands on a rebuild kit

It can be very difficult to bleed a dry caliper and a dry brake line, don't know if this is the best method but after some frustration this is what I do: I use compressed air at the caliper port to force the pads against the rotor, then remove the caliper. I fill the caliper with fluid thru the brake line port. I then connect it to the brake line and use a screw driver to force the piston(s) back into the caliper, this pushes the fluid up to the master cylinder reservoir. Install the caliper and operate the lever to push the piston out so the pads contact the rotor. At this point enough air has been purged from the system that if you don't have a firm lever you can do a normal bleed.

Make sure your handle bars are turned to the left so that highest point(which is where the air will sit) is not actually inside the master cylinder. Even doing it correctly can take some time, and also try pulling the lever in and letting it (snap) back out and tapping the master cylinder with something solid because the vibrations might get out some trapped air. And also make sure your brake line doesnt have any high points where air can sit before the master cylinder.

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