Bleeding braided brake lines

leguitos · L Plate Warrior Joined: 20 Nov 2013 Karma :

Hi guys,

I've decided to swap my old 10 year rubber brake hoses for some new braided hoses, on my 2002 deauville (NT650V2).

The problem is on bleeding. So after fitting the hoses and pumping the system with the pump, open nipple, close nipple, release lever and repeat, I managed to get new brake fluid coming out of the nipple; but when I pump the lever I dont see the old brake fluid moving in the plastic tube connected to the nipple. Anyway, when I take that plastic tube I can see brake fluid coming out of the nipple. The thing is: when I press the lever it still feels like there's no pressure in the system and the brakes don't work. A also don't see the master cylinder fluid level decreasing when I press the lever...

I tried leaving the lever tied overnight to increase the pressure but that didn't work as well.

Any ideas?

CaNsA · Super Spammer Joined: 02 Jan 2008 Karma :

Sounds like you have air trapped in the master cylinder.

If you have a side stand, put the bike on it.
Bars to full left lock.

Then bleed the brakes.

leguitos · L Plate Warrior Joined: 20 Nov 2013 Karma :

Thanks mate.

Will try that

cdzr · Derestricted Danger Joined: 20 Nov 2013 Karma :

Buy a 100ml syringe and push the fluid up from the nipple or suck it out.

Raffles · World Chat Champion Joined: 14 Apr 2009 Karma :

davebike · World Chat Champion Joined: 15 Nov 2013 Karma :

The syringe trick use a short bit of pipe to connect to the bleed screw should work
If not Get a BIG rag put it under the master cylinder, remove the banjo bolt, put you finger over the hole and work the master cylinder until fluid forces it way out passed your finger replace the banjo bolt quickly and try bleeding again

In the workshop I use pressure to add fluid from the bottom bleed screw or a continuous vacuum to suck fluid though

Dave
____________________
Dave
NC750Xdct + others at work !
davebike1@gmail.com

skatefreak · World Chat Champion Joined: 06 Feb 2010 Karma :

With my NSR I had a similar situation,
had worked the brake fluid through the system and was going through fine but the lever just want stiffining up as there was air trapped in the system.
Spent hours on and off trying this and that and eventually got quiet annoyed and tried hammering the lever very very quickly with a tube over the nipple and the nipple open (so once the tube is full of fluid, air cannot work its way back).

Low and behold, the agitation worked the air free and the brakes were back to where they should be a minute later Smile

Try it, go mad Wink

-Jvr

Robby · Dirty Old Man Joined: 16 May 2002 Karma :

Normal bleeding (opening the bleed nipples) is to remove air from the tiny pocket at the top of the calipers. If your lines are full of air, you're just trying to run the wrong way up an escalator. The air bubbles will rise up the line, the fluid is trying to move down the line, so all you do is gradually pump fluid out without moving the air.

Close the bleed nipples, fill the master cylinder, keep pumping the front brake slowly for about 15 minutes. Bubbles will come out of the master cylinder.

Once the lever has firmed up a lot, bleed at the bleed nipples. You should only need one little pump on each side to get the air out.

Air rises through fluid. Let nature make the job easy.