Priming the master cyclinder

[Alfa156V6]

All I have changed the brake lines on my bike to braided, however I can not get the master cyclinder to prime with fluid.
Is the only way to do this from the caliper up and if so how much pressure is required.

[warby221]

I use a large syringe and a rubber pipe to literally suck the fluid through to get it started just open the bleed nipple connect the pipe connect the syringe and it draws the brake fluid right down the line for you then when primed bleed as normal

[Alfa156V6]

Thanks for the tip I will give it a try. I can bleed the brakes but get no pressure at the lever so I assume I must have an airlock.

[Jaglifter]

Alfa,
I've had this problem on a number of bikes. You just have to be persistent and keep steadily pumping away. I've even given up and left it overnight to see if gravity helps! Warby's suggestion seems a good one.

[Alfa156V6]

Did try all afternoon yesterday and all this morning (good job the weather is crap) and gave up.

I am thinking of trying a banjo with a bleed nipple in it for the master cyclinder.

Anyone know if its the 10mmx1mm or 10mmx1.25mm.

[sirch345]

Did try all afternoon yesterday and all this morning (good job the weather is crap) and gave up.

I am thinking of trying a banjo with a bleed nipple in it for the master cyclinder.

Anyone know if its the 10mmx1mm or 10mmx1.25mm.

Not sure which thread pitch you need, but that could well be the problem air is holding up at that joint on the master cylinder. You could try unbolting the master cylinder and keeping that end with the banjo bolt lower than it is when on the bike,

Chris.

[Jim67]

I have used the syringe method before, you can send the fluid either way to rid the air lock, if you push the fliud up the lines then make sure you have enough room in the resorvoir for the fluid you push up or you end up with it all over your bike !!!!

Jim

[Alfa156V6]

All thanks for the tips, its seems you were all right and persurverance was all that was needed.

In the end and after several hours I managed to sort it out.

[sirch345]

Well done mate, glad to hear you got it sorted

I bet you are too

Chris.

[Jaglifter]

Glad you got there in the end Alpha.

One tactic I've not tried myself on a bike, but works when bleeding the clutch on BMWs, is to connect up a tube from the brake bleed nipple to the clutch slave cylinder bleed and by coordinating brake pedal and clutch along with some deft spanner work, use the brake master cylinder to force fluid up into the clutch master cylinder.
Takes two people to to it though.
(Phew... that took longer than I thought. I need a lie down now )