all of a sudden lost back brakes on 14 yz450

i seen a few threads regarding this issue but i wanted to explain exactly what happened with mine. I was riding in a gravel pit hitting jumps, etc. and my brakes were fine, and then all of a sudden i went for the back brake and the pedal went through the full stroke and didnt give me any braking power. it will not build any pressure at all when pumping it. When it happened there seamed to be an oily film on the master cylinder but when i try and pump the brakes now, there are no apparent leaks and no film on the master cylinder.

 

I may have gotten a bit of air in the line a couple nights ago when i opened the bleed screw with the brake pedal up, however i couldnt get any pressure before that anyways.

 

So would my best plan of attack be to bleed the brakes properly, or would you assume that there is a failure in the master cylinder?

 

thanks 

Start by bleeding the breaks and go from there

Bleed them first.  Be aware as you do so that air bubbles love to set up shop in the banjo fitting where the line connects to the master.  Once you establish reasonably clear fluid flow at the bleeder, loosen the line at the master and either push the pedal down and hold it, or push the brake pads back some, and retighten the line. 

Bleed them first. Be aware as you do so that air bubbles love to set up shop in the banjo fitting where the line connects to the master. Once you establish reasonably clear fluid flow at the bleeder, loosen the line at the master and either push the pedal down and hold it, or push the brake pads back some, and retighten the line.

Thanks for the reply. I am currently bleeding the brakes now. I am getting a lot of air bubbles coming out of the bleeder. The brake pads do not move at all with the application of the brake. I assume this is normal when bleeding them. Edited by ttr230rider6

So I just finished bleeding the brakes. I kept bleeding until I got a steady flow of fluid with no bubbles. I then loosened the line going to the M/C, held the brake pedal down and retightened and I am still with zero pressure. The piston in the calliper does not move, so therefore the pads don't move.

What should my next move be??

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