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NoOne65

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9 hours ago, NoOne65 said:

 

I did leave the cap on but I dont understand how that can put air in the system

It can't.

 

You can't get air in the system without opening the system which you didn't do.  First you stated that it was spongy after changing pads, later stated that it was already spongy.  You're all over the place with all your diagnostics/symptoms on this bike.

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31 minutes ago, blackhawkxx said:

Is it possible that it had air stuck in the system somewhere from before and it moved?

 

 

sure its possible but the fact remains I still cant get any air out of the bleed screws

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dont know if your working from a workshop manual or not so have scanned these from my haynes manual 

 

bottom page first then top page.

 


 

img003.jpg

img002.jpg

Edited by poida
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22 hours ago, poida said:

Did you do a full flush of the system or just try bleeding it.reason i ask is the brake fluid in it may be contaminated. 

 

I didnt do a flush just bleeding...I did order a rebuild kit

 

 

Thanks Everyone

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As shown in the Manuel, you can bleed the linked brake system on the Bird properly and thoroughly without the use of a vacuum bleeder but it is a pain in the butt. The job will require 2 people and should not  be attempted by yourself.

If there are no other issues other than air in the line, then the spongy rear should disappear, since a properly bled system will expel all the trapped air.

 

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  • 4 months later...

Mike had complained that my brakes were soft at RAcerXX a few years back.

Life has kept me a slacker the last couple of years.

 

I put a new tire on last month. So I bought a new My T vac from harbor freight and had at it.

First pulled the windshield, for better access to master cylinder.

Then I removed all fluid from the reservoir, and wiped it clean.

I drained most of the fluid from the rear reservoir too.

I then cleaned the calipers and pushed the cylinders in.  This back blead master cylinder, no air at the master cylinder.

I then put some 1/4 wood between the brake pads, since my wheel was still off.  This kept the Pistons from being driven out of the caliper, and reduces the volume of fluid in the whole system.

This also limits room for air.

 

The My T vac adaptor ends that connect to the bleeder suck.  They swell and leak quickly with DOT4, so I found some fuel line that was a tighter fit.

 

With this setup, I could pull and hold a vacuum.

Topped the reservoir and started bleeding.

I had a helper keep topping, while I bled.  This way, I had non-stop fluid flow.

 

Bubbles still show in the clear tubing, but they are coming through the threads of the bleed valve, not the system.

 

The front lever firmed up immediately.

 

I then did the same for the rear master cylinder.  It firmed up by bleeding the lower FRONT caliper bleeds.

Next bled the rear caliper.

 

Put the front wheel on, pumped the brakes until the pads hit the rotors, the topped both reservoirs to the level lines.

 

Both brakes are now extremely firm, no sponge.

 

The MyTvac was less than $40.00 and worth every penny.

 

Just don't tell Mike ( Zero) that he was right about my brakes. 😎

Edited by redxxrdr
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A quick search shows rebuild kits for $40.00.

I just rebuilt the front master on the SV, the XX rear looks even more simple.

 

The hardest part was finding a inner circle clip tool with long tips.  

I bet you could do it easily in a afternoon.

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4 hours ago, Perky said:

I wish a simple bleeding and/or flushing would do the trick.  I've bled the lines multiple times with zero results.  I'm leaning towards a bad rear master cylinder at this point.  

 

 

 

 

 

It's rare to have just a mushy pedal from a bad master.  Maybe if the cylinder is pitted or otherwise damaged just in the first part of engagement and that cylinder damage hasn't damaged the seals...unlikely.  You could have air in the master which can sometimes be hard to get out.  Pressing the caliper pistons in will usually do it.  Also, leave the cap loose 'till you pump the pistons back out so you don't make a vacuum in the reservoir.  You might have an issue with the linked system but I haven't had one in so long I don't remember the plumbing.

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Another thing that may be worth considering is the state of the caliper seals. If they are compromised you may get air in the system from that end. When I had more time in my life I made it a point to disassemble calipers and clean/rebuild them. Never had problems with those brake systems...

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Great advice all around.  In the next week or so, I'll try each of these recommendations.

 

Dave, I have steel braided lines.  I can't remember the manufacturer...it's been about 6 years or so.

 

I know I'm hijacking this thread, but NoOne65 hasn't piped in yet.  Sorry for the hijack.

 

Just to clarify, this issue popped up right after the lines were switched to steel braided lines. ( And yes, I know I'm a slacker for not tackling this problem sooner.)  I would say the rear worked as intended for about 3 months, then the rear began to get mushy. I've bled the system countless times and it doesn't seem to help.

 

 

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34 minutes ago, Perky said:

Great advice all around.  In the next week or so, I'll try each of these recommendations.

 

Dave, I have steel braided lines.  I can't remember the manufacturer...it's been about 6 years or so.

 

I know I'm hijacking this thread, but NoOne65 hasn't piped in yet.  Sorry for the hijack.

 

Just to clarify, this issue popped up right after the lines were switched to steel braided lines. ( And yes, I know I'm a slacker for not tackling this problem sooner.)  I would say the rear worked as intended for about 3 months, then the rear began to get mushy. I've bled the system countless times and it doesn't seem to help.

 

 

 

 

 

solved it..bought a new bike...but seriously, I never got a chance to fix it before the motor siezed

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Look at the hose, hoses if still linked, while pressing the pedal just to make sure it's not defective and bulging somewhere.  Did it suddenly get mushy or slowly deteriorate?  Is it uselessly mushy or just a little soft?  Still linked?  Did you do any adjusting to the pedal linkage when you did the hoses?

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Does it become uselessly mushy from just sitting or only while riding?  If only when riding it could be a warped rotor pushing the pads back, or maybe a caliper mounting issue.  If it does it just sitting I would start by checking to make sure there's not a vacuum in the reservoir.  Remove the fill cap and diaphragm, pump up the brake, close it up, then see.

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Steve,

After you pump up the brakes, does the pedal hold?

No evidence of leaks anywhere?

If so, I really think that a good bleed will fix it.

Because this comes up often, I pirated a good write up and some pictures.

 

The big thing about Honda's linked brakes is that there is no fluid connection between the front and rear Master cylinder circuits.

 

 

image.jpeg

The front brakes on the XX have three pistons per caliper.  The two outer pistons are driven by the hand lever and bled from the top bleed valve on each front caliper.

The rear brake caliper also has three pistons.  The outer two pistons are driven by the rear brake lever. 

 

Then we add the linking.  

 

 The center piston on the front brake calipers is driven by the rear foot lever master cylinder.  It gets it's fluid from the rear brake reservoir.

Bleeding of the front caliper, center piston is done using the lower bleed screw on each front caliper, and the rear master cylinder and reservoir.

 

The rear caliper, center piston is driven by a third master cylinder that is mechanically connected to the left front caliper.

But it gets the fluid from the rear reservoir.

 

The rear piston is driven when the front brake lever is pulled while the BIKE IS MOVING.  

When the bike is moving, the left caliper rotates some with the rotor and actuates the third master cylinder.

If the bike is not moving, there is no rotation of the caliper, and no actuation of the center piston on the rear brakes.

 

This explains why we can hold the front brake lever, and do a burnout without dragging the rear brakes.  The front wheel does  not turn, so the rear gets no brakes through the third master.

 

So after all this,

My experience is that it is easiest to bleed the brakes with a MyeTvac style bleeder.

I get someone to help me by keeping the reservoirs full.  

This way, I can pull a constant vacuum on each line, and get the air out.

 

The rear master cylinder must not only feed the rear caliper through the short rear brake lines,  It must also feed fluid forward through longer lines, and the third master cylinder, back to the rear caliper.   That's a lot of places to hide air, and make the rear pedal soft.

 

pirated bleed procedure

 

another procedure with pictures

Edited by redxxrdr
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On 8/18/2016 at 9:59 AM, superhawk996 said:

Does it become uselessly mushy from just sitting or only while riding?  If only when riding it could be a warped rotor pushing the pads back, or maybe a caliper mounting issue.  If it does it just sitting I would start by checking to make sure there's not a vacuum in the reservoir.  Remove the fill cap and diaphragm, pump up the brake, close it up, then see.

 

Sitting.  It loses pressure with in 5 seconds or so.

 

 

18 hours ago, runninn said:

I went thru this once... that was more than enough. I never was that impressed w/the linked brakes. The JAWS delink kit solved the issue ....

 

I have the delinking kit from Jaws, and will go that route, if all else fails.

 

 

Craig,

I just developed 2 leaks that I caused while redoing some lines that were run improperly from when I had a shop install the braided lines.  The system was not leaking before this, so I have to fix those first before I can get into it any further.  I have a vacuum pump now and ordered a rear MC rebuild kit that will be here next week.  Since I'll have to take the lines that are leaking off anyway, I'll pull the MC and do the rebuild, then I'll use the vacuum bleeder to  bleed the system.  

 

Thanks for all the replies on this.  I'd like to keep the linked system, but if I can't chase down the issue, I'll just delink and call it a day.

 

 

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17 hours ago, redxxrdr said:

 

 

image.jpeg

 

 

 

The rear caliper, center piston is driven by a third master cylinder that is mechanically connected to the left front caliper.

But it gets the fluid from the rear reservoir.

 

 

pirated bleed procedure

 

another procedure with pictures

The picture shows the rear center driven by the pedal and the outers driven by the third master, backwards of what's described.

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