How to bleed brakes after i replaced the master cylinder?

[crazydj]

Hi guys!

 

I replaced my brake master cylinder and i am trying to get back the brake fluid inside the brake hose.

 

Basically i

 

1) Removed the brake hose from the old master cylinder.

2) Removed the old master cylinder from the bike.

3) Install the new cylinder into the bike.

4) Attached the brake hose to the master cylinder.

5) Pump the brakes like hell for the past 15 minutes.

 

I see bubbles. Tiny bubbles. Damn pathetic bubbles coming out from the brake fluid reservoir. Still no pressure in the brakes.

 

Any recommendations on what i can do now? Last time, the same thing happened when my mech changed my brake hose, I know he tried to use the vacuum bleeder but nothing happened, nothing was sucked out. So he just fully depress the lever with a cloth and i waited for more than an hour, and hey presto! I got brake pressure.

[BLACK COMET]

U will need abottle of new brake fluid.

1 phillips screw driver to open ur brake reservoir.

1 8mm or 10mm close loop wrench.

1 length of air hose. Fish shop type

 

2 person to do that will be nice

 

First Fill the reservoir to full.

 

Put the wrench into the bleeder screw first. Then attach the air hose. The end of the hose put in some container.

 

Pump the level a couple of times. and hold

 

Open the bleeder nut (do not releease level) U will notice that the level will go in more. But do not let go.

 

Close bleeder nut. Only after the bleeder nut is close then u release the level.

 

Repeat the above steps until u get the desired hardness of the level.

 

Also make sure the brake fluid is enough. top up if not enough.

 

And 2 person is easier. One open nut, one pull level.

[BLACK COMET]

U will need abottle of new brake fluid.

1 phillips screw driver to open ur brake reservoir.

1 8mm or 10mm close loop wrench.

1 length of air hose. Fish shop type

 

2 person to do that will be nice

 

First Fill the reservoir to full.

 

Put the wrench into the bleeder screw first. Then attach the air hose. The end of the hose put in some container.

 

Pump the level a couple of times. and hold

 

Open the bleeder nut (do not releease level) U will notice that the level will go in more. But do not let go.

 

Close bleeder nut. Only after the bleeder nut is close then u release the level.

 

Repeat the above steps until u get the desired hardness of the level.

 

Also make sure the brake fluid is enough. top up if not enough.

 

And 2 person is easier. One open nut, one pull level.

[crazydj]

U will need abottle of new brake fluid.

1 phillips screw driver to open ur brake reservoir.

1 8mm or 10mm close loop wrench.

1 length of air hose. Fish shop type

 

2 person to do that will be nice

 

First Fill the reservoir to full.

 

Put the wrench into the bleeder screw first. Then attach the air hose. The end of the hose put in some container.

 

Pump the level a couple of times. and hold

 

Open the bleeder nut (do not releease level) U will notice that the level will go in more. But do not let go.

 

Close bleeder nut. Only after the bleeder nut is close then u release the level.

 

Repeat the above steps until u get the desired hardness of the level.

 

Also make sure the brake fluid is enough. top up if not enough.

 

And 2 person is easier. One open nut, one pull level.

 

I have successfully bled my brakes a couple of times. The thing is that, this time, i changed the whole brake reservoir and pump because the old one was damn rusty. Filled the reservoir with brake fluid, then pump, pump until non stop, still got no bubbles come out into the brake fluid reservoir.

 

Did the regular bleeding, pump lever, open bleed screw, close, release lever. Nothing comes out of the bleed screw. Just air and some very little brake fluid. Do this many times also, just air come out. And yes, i have all the necessary stuff. I've been bleeding my brakes for the past few weeks and everytime i bleed them ,they are good, but after it rains, it get crap so i have to keep bleeding time and again.

 

Normally how is it done if new brake hose or brake reservoir/ master cylinder?

 

PS: I changed back to the old brake master cyclinder, and when i pump pump pump, i can see alot of tiny bubbles coming into the reservoir. Now tired, relax while i leave the lever in permanent 'depress' mode with a rubber band. I slowly see bubbles rising to the surface when i do this. I think maybe the new cylinder faulty or what not. Its those chiong type i open up and see also, the original quality, even how rusty it is, still seems more sturdy.

[crazydj]

Oh my...

 

My old brake pump + reservoir works lol. I think the new chiong one spoil or something.

[hachi]

Oh my...

 

My old brake pump + reservoir works lol. I think the new chiong one spoil or something.

 

U should not releases the bleeder till you got the pressure...I changed my MC before, can be a bit terrifying...Ensure you tighten all hose and bleeder than depress and release the pressure tilll u go the pressure back then bleed as per normal.

[hachi]

Oh my...

 

My old brake pump + reservoir works lol. I think the new chiong one spoil or something.

 

U should not releases the bleeder till you got the pressure...I changed my MC before, can be a bit terrifying...Ensure you tighten all hose and bleeder than depress and release the pressure tilll u go the pressure back then bleed as per normal.

[crazydj]

U should not releases the bleeder till you got the pressure...I changed my MC before, can be a bit terrifying...Ensure you tighten all hose and bleeder than depress and release the pressure tilll u go the pressure back then bleed as per normal.

 

That's the problem. I never did get pressure on the new chiong pump. Checked everything, double check everything. The brake light switch also not working lol.

[crazydj]

U should not releases the bleeder till you got the pressure...I changed my MC before, can be a bit terrifying...Ensure you tighten all hose and bleeder than depress and release the pressure tilll u go the pressure back then bleed as per normal.

 

That's the problem. I never did get pressure on the new chiong pump. Checked everything, double check everything. The brake light switch also not working lol.

[BLACK COMET]

DOA chiong pump?

 

Thought YBR original parts are cheap?

[Tachnicolour]

Might need to prime the new MC. Air in MC when you attach a new one which is empty can be a b****.

 

Try to see if that's the case.

 

1) Fill your new MC with fresh fluid.

1a) Ensure area underneath MC is covered with rags or have a catch bin to catch brake fluid. Cover all nearby paintwork if you value your paintwork with something non-permeable.

2) Cover the fluid exit port on the MC with your finger. Do NOT install the banjo bolt/brake line. Keep the banjo bolt on standby though, within reach.

3) Depress the brake lever, keeping finger slightly off the port.

4) Seal port with finger, release brake lever.

5) Repeat 3&4.

6) At a point, you will feel fluid forcing past your finger. That's when it's primed.

7) Keep port covered and grab the banjo bolt, reattach whilst allowing as little air as possible into the port. Don't worry, air will get in, just make sure that the port isn't facing downards and drains empty.

 

8) Bleed as per normal. Your MC should be pushing fluid through at this point.

 

Hope it helps.

[crazydj]

DOA chiong pump?

 

Thought YBR original parts are cheap?

 

For the china parts, its like, many factory produces the part, then they smack an original yamaha sticker on it. So in other words, you don't really know what is the true original one.

 

Might need to prime the new MC. Air in MC when you attach a new one which is empty can be a b****.

 

Try to see if that's the case.

 

1) Fill your new MC with fresh fluid.

1a) Ensure area underneath MC is covered with rags or have a catch bin to catch brake fluid. Cover all nearby paintwork if you value your paintwork with something non-permeable.

2) Cover the fluid exit port on the MC with your finger. Do NOT install the banjo bolt/brake line. Keep the banjo bolt on standby though, within reach.

3) Depress the brake lever, keeping finger slightly off the port.

4) Seal port with finger, release brake lever.

5) Repeat 3&4.

6) At a point, you will feel fluid forcing past your finger. That's when it's primed.

7) Keep port covered and grab the banjo bolt, reattach whilst allowing as little air as possible into the port. Don't worry, air will get in, just make sure that the port isn't facing downards and drains empty.

 

8) Bleed as per normal. Your MC should be pushing fluid through at this point.

 

Hope it helps.

 

Yeah i thought of this. Thanks man. But i was also wondering, how come my old MC which was bone dry i can get pressure so easily?

[ooitn]

The reason why you encounter such situation was that, you got air in the system.

The best way to do it (replcaing brake oil) is:

1) ensure all connection is tight except the pipe to the reservoir..

2) connect a vacuum pump to the hose that to the reservoir, so the it kind of suck the air out from the brake..

3) feed the new oil from the brake via release screw.

4) once the oil fill the system , tighten the release screw, disconnect vaccum pump and reconnect the hose to reservoir and fill up the reservoir after that.

5) cap back the reservoir, and release quater turn of the release screw, slowly squeez the brake level to allow a littel oil flow out from the brake and lock tight immediately after that.

6) Your brake will be there...remember DOT4 harmful to all paint work..so clean after that. DO NOT ALLOW AIR IN THE SYSTEM.