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Discussion Starter #1 (Edited)
Hello Hondatwins,

I did an introduction to this bike when i joined the forum a few years back, but life happened and it ended up stored for about 3 years. Since a few weeks i have been working on my (European) 84 cm400t, getting it back to riding condition.

Even after years of neglect the engine fired right back up without any hiccups, so happy me. Last weeks i have been lurking this forum for info and did a lot of basic maintenance which was fun.

Before stalling the bike i noticed the problem of the sticky in this section: my front brake seized up after some use. While doing a few small test rides last week i was reminded of this annoying problem again and started following the steps of the sticky thread.

Steps i completed:

- Bled the old brake fluid
- Disconnected the master cylinder
- removed the reservoir
- Cleaned the MC: left it soaking overnight and used a needle to pry out all the gunk in the 2 holes
- Assembled it back on the bike

Now i am left with no brake fluid in the setup and tried to bleed/reverse bleed it back in. Used the search and tried every method i could find.
Confusion and frustration followed for about 2 days now and i have no idea what to do.

What i tried and my symptoms:

No pressure on the brake lever yet. Filled the reservoir and when i press the lever and open the bleeder: little puffs of air and fluid come out.
No matter how long i try to repeat the steps of pumping/bleeding the level in the resevoir does not go down.

After this failed tried reverse bleeding:

Disconnected banjo bolt at MC, stuck a tube and syringe at the (opened) bleeder and injected fluid. New fluid comes out the other end of the line.
So i connect the banjo bolt back to MC and try to inject again, hoping to see the reservoir fill back up. NOPE doesnt work. Pressure on the syringe builds up but fluid does not flow back up. I tried in combination with moving the brake lever, but no succes as well.
What i thought was strange: when pressing the brake lever, fluid came back out the bleeder and into the syringe, but i cannot get it back up.

EDIT: also tried putting new fluid in the reservoir and using the syringe to suck out fluid from the bleeder, no success.

I could really use your opinions here, what am i doing wrong?

Thanks in advance.
 

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I had a very similar experience, in my case I was simply not opening the bleeder wide enough each time. I was cracking it open and getting a little puff of air, but it was not until I opened the bleeder more fully that I got the bleeding you'd expect.
 

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Discussion Starter #3
Thanks for your response, tried opening further but made no difference to my symptoms
 

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The only other advice I have is to be sure you are bleeding into to jar partially filled with brake fluid, and be sure that the hose you use to connect the bleeder nipple is a tight fit so no air can slip in.

I elevate the jar above the bleeder, it's a more natural position for air to flow up and fluid to flow down.

Open the bleeder wide and pump away. I experienced the same frustration of essentially no pressure building up at the brake lever until I opened the bleeder wider with the above set-up, in fact I was ready to completely replace all the braking components, I was so frustrated.
 

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I have cured sticking brakes with a caliper rebuild. The piston gets gooey and sticks
keeping the brake applied. Take a rubber mallet and bang on the caliper to try to release it.
Hit it hard, it will probably release the brake. I have a CB750 with sticking brakes, front and rear.
If I need to move it I whack the calipers a few times and roll it to where I want it. Got to fix those brakes, soon.
 

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My master cylinder was filled with rusty gunk when I got the bike, here's what I had to do to get 100% brakes again:

Replaced MC, rebuilt the caliper which included replacing the piston and seal, replaced the brake line with stainless, new EBC pads and now I can stop when I want to. You should take the caliper apart while you're there, there's a video on youtube and it's not that hard to do
 

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When you cleared the 2nd tiny hole in the master were you able to shine light thru it? Did you reclean the bore after and retest with the light. This is sounding like the relief port, small hole, is plugged up again.
 

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Discussion Starter #9
Thank you all for for your replies. I took off the MC again and noticed the following:

Even though i can see the piston moving through the little hole in the bottom, when i put fluid in it, it just wont flow down and out of the hole where the banjo bolt screws in. How could this be and can i unclog it somehow?

I'm going to look at aftermarket or replacement MC's that are local to me but in the meantime will still try to fix it and appreciate any tips.
 

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Discussion Starter #10
When you cleared the 2nd tiny hole in the master were you able to shine light thru it? Did you reclean the bore after and retest with the light. This is sounding like the relief port, small hole, is plugged up again.
Just saw your reply and checked, put my phone flashlight into the holes but nothing shining through. Also now that i took the part off and it dried, the piston seems stuck in place now.. bad news i guess.
 

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If you have compressed air handy you should be able to blow the piston out of the cylinder, just be sure there's a rad of something to catch it first. Sometimes the rubber cups get rolled over inside and cause this
 

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When you add the brake fluid, load it from the bleeder. It forces the air to go up. Tilt the handlebars to avoid the bend going into the MC. Air likes to stay in there. The first time I tried to bleed my CM450C it drove me crazy.
 

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Discussion Starter #13
Just an update to close this and for anyone possibly interested: The problem was that my Master cylinder was not letting ANY fluid through. very strange because it was almost unnoticeable that it was clogged until i put fluid in the reservoir and pumped it without a hose attached and saw nothing coming through.

I took the easy way out and ordered an aftermarket MC on Aliexpress (yup) for 15 Euros which worked perfectly: Reverse bled the fluid back in and my sticking brake problem is solved as well.

Thanks for your suggestions.
 

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I'm afraid it sounds like it's time for a rebuild. The only special tool you will need is a set of snap ring pliers. You should be able to get a rebuild kit through a Honda dealer.
 
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