Can't get rear brakes to bleed

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7/10/2020 5:28 PM
Edited Date/Time: 7/10/2020 5:29 PM

Rebuilt the master cylinder and caliper this week. I top up the master, pump, open bleeder, hold down the pedal, shut bleeder, release pedal to no avail. I have tried using a syringe filled with fluid to force fluid up to the master, and saw quite a bit of bubbles pop at the surface but still no resistance at the pedal. I've noticed while having the bleeder open a small amount of fluid comes out where the bleeder and banjo meet, Normal or something I need to address? Anything else I should try? I am using a tool like this as well. Bike is a 2016 125SX. Photo

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7/10/2020 5:33 PM

I know most people have success with reverse bleeding with a syringe by shooting fluid in through the caliper.

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7/10/2020 5:44 PM

Bleed it at master Banjo bolt first, then caliper

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7/10/2020 5:50 PM

Beaudzz118 wrote:

Bleed it at master Banjo bolt first, then caliper

This. If you don’t bench-bleed the master, you’ll make things really hard on yourself.

If you bleed everything and still don’t have a firm pedal/lever, you can also zip-tie the lever back, or weight the pedal, with the bleeder closed, and leave it overnight. I’ve gotten two front brakes this way that refused to firm up no matter what I did.

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7/10/2020 6:01 PM

Beaudzz118 wrote:

Bleed it at master Banjo bolt first, then caliper

How do you bleed the master with no bleeder valve?

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7/10/2020 6:09 PM

Beaudzz118 wrote:

Bleed it at master Banjo bolt first, then caliper

Rickyisms wrote:

How do you bleed the master with no bleeder valve?

He means to use the banjo bolt like a bleeder. Push the pedal down, crack the banjo, tighten, and let the pedal up/repeat.

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7/10/2020 6:12 PM

You might need to rebuild the brakes I had the same in mine...

Small kit and 10 minutes and you will have pressure again.

Photo

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7/10/2020 6:13 PM

If one of those O rings is damaged you’ll be bleeding all day.

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7/10/2020 6:31 PM

Deja New wrote:

You might need to rebuild the brakes I had the same in mine...

Small kit and 10 minutes and you will have pressure again.

Photo

I rebuilt the caliper today and the master cylinder yesterday.

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7/10/2020 7:37 PM

Pull the rear wheel, put a wrench or shim between the shoes and bleed the caliper holding it above the master cylinder.
Air gets trapped in the line. The air will travel up to the caliper and out the bleeder. It easier with 2 people. Good luck.

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7/10/2020 8:10 PM

Beaudzz118 wrote:

Bleed it at master Banjo bolt first, then caliper

Rickyisms wrote:

How do you bleed the master with no bleeder valve?

omalley wrote:

He means to use the banjo bolt like a bleeder. Push the pedal down, crack the banjo, tighten, and let the pedal up/repeat.

Awesome I’ll try it tomorrow after work.

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7/10/2020 10:44 PM

Buy a vacuum bleeder and it will be done in about 2 mins max. It’s the only way to do them quick and easy, and you can easily do it yourself.

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7/11/2020 4:25 AM

dancolvin633 wrote:

Buy a vacuum bleeder and it will be done in about 2 mins max. It’s the only way to do them quick and easy, and you can easily do it yourself.

yip cheap as as well and it s great tool for future use to put fresh fluid through

also try zip tie`n the pedal down and leaving it overnight ive had a few difficult ones in past and this helps get it started so you can do the normal bleeding process

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7/11/2020 5:04 AM

dancolvin633 wrote:

Buy a vacuum bleeder and it will be done in about 2 mins max. It’s the only way to do them quick and easy, and you can easily do it yourself.

Vacuum bleeders won’t work on your bike. It will pull air in around the puck

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7/11/2020 5:06 AM

Just rebuild your master cylinder. You should have no problem bleeding it, obviously your seal is shot.

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7/11/2020 5:20 AM

Photo
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7/11/2020 5:29 AM

May need a different banjo bolt with 2 holes in it. I could not get my 13sx front brake to bleed. The ktms used to only have 1 hole in the banjo bolt vs 2 on the Japanese bikes, making it difficult to get air out.

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7/11/2020 5:29 AM

Rickyisms wrote:

How do you bleed the master with no bleeder valve?

omalley wrote:

He means to use the banjo bolt like a bleeder. Push the pedal down, crack the banjo, tighten, and let the pedal up/repeat.

Rickyisms wrote:

Awesome I’ll try it tomorrow after work.

Agree with the banjo bolt. I remember not being able to get pressure after full rebuilds & totally empty lines. Ever since I started at the banjo bolt , I can get pressure quickly at the caliper.

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7/11/2020 7:05 AM

Rick Amatuzio wrote:

Just rebuild your master cylinder. You should have no problem bleeding it, obviously your seal is shot.

Master cylinder was rebuilt two days ago caliper was rebuilt yesterday.

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7/11/2020 8:05 AM

dancolvin633 wrote:

Buy a vacuum bleeder and it will be done in about 2 mins max. It’s the only way to do them quick and easy, and you can easily do it yourself.

Yep mityvac for the win. Got mine from harbor freight for $40. Nice to have

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2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

7/11/2020 8:38 AM

Rick Amatuzio wrote:

Just rebuild your master cylinder. You should have no problem bleeding it, obviously your seal is shot.

Iv been using one for 10 years and it’s worked every time 🤷🏻‍♂️

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7/11/2020 8:40 AM

dancolvin633 wrote:

Buy a vacuum bleeder and it will be done in about 2 mins max. It’s the only way to do them quick and easy, and you can easily do it yourself.

Rick Amatuzio wrote:

Vacuum bleeders won’t work on your bike. It will pull air in around the puck

Unless of course the brembo master is different then a Nisan master... Iv always used them on my Kawis and Honda’s

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7/11/2020 8:44 AM

Rick Amatuzio wrote:

Just rebuild your master cylinder. You should have no problem bleeding it, obviously your seal is shot.

He already did this.

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2017 RMZ450
2005 YZ250-sold :,(
1998 YZ250
2005 KX250F

80% of the time it works every time
IG @hamdaddyof2 & @2HRacing
Thanks to : Factory Effex, N2Dirt, Acerbis, DT1, Fasthouse, Matix, FMF, ASV, 100% & Mika Metals

7/11/2020 3:34 PM

Bleeding at the master cylinder worked! Took three cracks before I had pressure. Thanks everyone and have a great weekend!

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7/11/2020 5:03 PM

Had a similar problem after all your replacement parts.

My adjuster for the front caliper was up too high. Turned it down some, pumping started.

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JS7 is the most entertaining rider since Hannah, my first hero,. even living in the frozen north.
Dirt biking from 11 to late 50’s, loves wood riding on the old 525.

7/11/2020 6:19 PM

Suction. Use your syringe reverse bleed set up but instead of forcing fluid in you will be sucking it out and refilling the master with fluid as you go.

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7/11/2020 7:41 PM

Make sure your adjustment is all the way open that'll stop it from going too.

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7/11/2020 8:42 PM
Edited Date/Time: 7/11/2020 8:43 PM

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7/13/2020 2:40 AM

go back to drum brakes

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7/13/2020 5:00 AM

crusher773 wrote:

Make sure your adjustment is all the way open that'll stop it from going too.

2nd that, I made the schoolboy error after a stone hit my front brake lever resulting in a damaged seal. Resealed the cylinder and didn't alter the distance adjustment on the lever so wasn't getting the full movement at the cylinder. Ran a full season with a shit front brake till I realised. Knobhead.

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