Front brake issues

[HungLow]

So I'm repairing the bike after my accident. Pretty much everything is working except my front brakes (new used master cylinder, but same pads and all, had just installed them before the accident). Now, the rear brakes work great, but the front ones do not even engage, the handle goes all the way down, tried bleeding it, nothing, do not see any leaks. Any ideas?wonder if it could be the cylinders or the master cylinder!?

[92xjunker]

Master appears to be faulty. I'd rebuild it.

[HungLow]

K I'm going to have to look into how to do that.

[Seft]

I did this the other day and it was quite straight forward, you will need some internal circlip pliers to do the job. If the new master cylinder isn't known to have worked at all I'd take the old piston out and just check there is no damage internally first as if it's significantly worn inside putting a new piston and seals in won't likely fix the problem.
I did have a bit of trouble keeping the piston pressed down to remove and then install the circlip, in the end used one screw driver through the mount holes and then used a flat blade screwdriver with insulation tape on the end levering against the other driver to push the piston down so I could hold it with one hand and do the clip with the other (hope that makes sense!?) If anyone has a better way I'd love to hear is as it was far from graceful!?

[HungLow]

Might have to just buy a new one in that case.

[Seft]

It wont take long to check if the cylinder is damaged inside, hopefuly you'll just find some ruined rubber parts as new OEM is expensive. I'm assuming when you say you bled them and that didn't work that there are absolutley no bubbles, even tiny ones coming up in the master cylinder or from the bleed nipples? Also before you take the cylinder appart, with the cap off the master cylinder pull the lever in and just let it snap back as this had disloged trapped bubbles from mine presviously.