Topic: Front brake master cylinder

[velo13533]

I have just rekitted my master cylinder and tried filling it on the bench  to see if it pumps fluid before I fit it on the bike.It doesnt?Should I be able to  pump fluid using the lever or have I done something wrong?Does the system need priming somehow.

[scondon]

 Much easier to check it and prime it when mounted.When it's not attached to anything it will suck air back in much too easily.I attach the cylinder to the brake line,remove cap from reservoir, then pull the lever slooooowly. You should see air bubbles rise at some point,this tells you fluid is getting in and priming the cylinder. Do this a few times until bubbles diminish, but do not pull the lever all the way back to the bar as this can damage the new seals. It won't "squirt" out the end but you should get it to dribble when it is primed.

  Post any further queries in the "Tech Forum" as you're likely to get more responses there

[dave75]

I usually go buy several large syringes from the local drug store.  Fill one with brake fluid, attach a small amount of rubber hose (vacuum line hose) to the nozzle..... attach the other end to the bleeder screw of your caliper.  Backfill and watch the level come up in the master cylinder.  Typically use this method for cars too.... especially when you can't get one primed.  Easy, Cheap, and effective.

Dave