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Discussion Starter · #1 ·
I picked up this 03 Bird in July and took it on a 2000 mile ride in September. About day 2 of the 6 day ride I noticed my rear brake pedal was bottoming out like I had lost all the fluid. I checked the reservoir and it had plenty of fluid. I was able to pump up the brake pressure by stabbing the pedal several times but after a few seconds it would go back to "0" pedal. I noticed brake fluid coming from the front Secondary Master Cylinder figured that was the source of my problem. If fluid is coming out, air might be going in. Front brake was working perfectly. When I got home I re-built the Secondary MC ( kits are still available for this part, not so much for other parts of the system). I bled both the front and rear systems numerous several times per the owners manual and techniques I found in the internet. I went through a quart of Dot 4 doing it. I am familiar with brake systems and how they work although this is my first linked brake system. I believe I did everything correctly. Still had the same problem although it was better. So I figured maybe the Rear Master Cylinder was the issue so I replaced it with a new one. What I have now is a rear brake pedal that "almost" bottoms out when the brake is applied and supplies about 10% braking. If I pump the pedal once I get about 75% brake, if I pump the pedal twice I have 100% normal brake. I can depress the brake pedal (in that 100% state) hang a weight on it to keep pressure on the lines and come back in an hour and the pedal is exactly where it was when I left it. 100%. If I let it sit for a few seconds it goes back to almost zero pedal. That's the mystery. If the new master cylinder was bad or if I still had a leak somewhere the pedal would go to the bottom and I would have fluid pooling under the bike. I'm hoping someone out there has experienced the same issue and can help. I actually like the linked brakes and would prefer to keep them if possible. The problem is some of the main components ( the Proportional Control Valve under the seat and the delay valve on the right fork) cannot be rebuilt and new replacement parts are no longer available. One more thing, I have both the VFR "riser bars" and the "Jaws spacers" on the bike. If I do have to de-link the brakes will the 60mm longer line be long enough? Has anyone de-linked the brakes with both VFR bars and spacers on their bird? Thanks for any advice
 

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I picked up this 03 Bird in July and took it on a 2000 mile ride in September. About day 2 of the 6 day ride I noticed my rear brake pedal was bottoming out like I had lost all the fluid. I checked the reservoir and it had plenty of fluid. I was able to pump up the brake pressure by stabbing the pedal several times but after a few seconds it would go back to "0" pedal. I noticed brake fluid coming from the front Secondary Master Cylinder figured that was the source of my problem. If fluid is coming out, air might be going in. Front brake was working perfectly. When I got home I re-built the Secondary MC ( kits are still available for this part, not so much for other parts of the system). I bled both the front and rear systems numerous several times per the owners manual and techniques I found in the internet. I went through a quart of Dot 4 doing it. I am familiar with brake systems and how they work although this is my first linked brake system. I believe I did everything correctly. Still had the same problem although it was better. So I figured maybe the Rear Master Cylinder was the issue so I replaced it with a new one. What I have now is a rear brake pedal that "almost" bottoms out when the brake is applied and supplies about 10% braking. If I pump the pedal once I get about 75% brake, if I pump the pedal twice I have 100% normal brake. I can depress the brake pedal (in that 100% state) hang a weight on it to keep pressure on the lines and come back in an hour and the pedal is exactly where it was when I left it. 100%. If I let it sit for a few seconds it goes back to almost zero pedal. That's the mystery. If the new master cylinder was bad or if I still had a leak somewhere the pedal would go to the bottom and I would have fluid pooling under the bike. I'm hoping someone out there has experienced the same issue and can help. I actually like the linked brakes and would prefer to keep them if possible. The problem is some of the main components ( the Proportional Control Valve under the seat and the delay valve on the right fork) cannot be rebuilt and new replacement parts are no longer available. One more thing, I have both the VFR "riser bars" and the "Jaws spacers" on the bike. If I do have to de-link the brakes will the 60mm longer line be long enough? Has anyone de-linked the brakes with both VFR bars and spacers on their bird? Thanks for any advice
I have 97’ seriously thinking about de linking.
I like linked also,but lets be honest they suck.
Can’t help you but,would love to know as well,good luck though.🏍
 

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Discussion Starter · #3 ·
What I think sucks about the LBS is Honda not supporting the system with replacement parts. When it's working properly the brakes are very good. My situation is a good example. Even though I completely lost my rear system I still had some rear brake due to them being linked. I don't think I'll be able to salvage them and when I de-link them I might have a "what was I waiting for" moment. It is a very complex system. I think Honda was just showing off a bit with it. A "Look what we can do" kind of thing.
 

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What I think sucks about the LBS is Honda not supporting the system with replacement parts. When it's working properly the brakes are very good. My situation is a good example. Even though I completely lost my rear system I still had some rear brake due to them being linked. I don't think I'll be able to salvage them and when I de-link them I might have a "what was I waiting for" moment. It is a very complex system. I think Honda was just showing off a bit with it. A "Look what we can do" kind of thing.
Yes they were showing off,lol the bike was ahead of it’s time,still is.
Your experience was one reason I haven’t de-linked,you still had brakes man,that was good.
Mine are sticking AGAIN,but they still work!
Hope you get it figured out,I would love to have a new Ducati,or an R1,but honestly the Bird is an all around perfect bike,sucky brakes and all.
 

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When you bleed the rear the first shot do you get a big air pocket?
I haven’t on the Blackbird,but that has happened with other bikes. That actually happened yesterday on a KTM dirt bike.
I was bleeding the clutch line on it,and filled it back up with DOT 4,and it worked for a few minutes then stopped working again.
What I do is take the brake,or the clutch line off right after the reservoir on the handlebars,and take a small funnel holding the line up,and fill the line up with fluid.I put a rag around the bottom of the funnel to catch any leaks.
That’s the procedure I use when I’m filling the system back up, I bleed the line from where it meets the reservoir,down.Once its full, I then screwit back on reservoir, and then make sure reservoir is full.
 

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Discussion Starter · #7 ·
beestoys: No I didn't. The only big air pocket released were from the front secondary master cylinder after I rebuilt it and the rear master cylinder after I replaced it which is what you would expect.
 

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Hmm
Ok I've seen the rear caliper catch a large pocket
It was introduced by the secondary on the front fork. The seal was going. Funny thing is it never leaked fluid
What it would do was pull air past the seals and work it back the the rear caliper. I would bleed out the pocket then after a couple weeks and be back.
 

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Ok
So looking at the factory diagram you could also be pulling air from the front calipers. Pedal actuation hits the left caliper first. The the right after the delay valve. The secondary is also activated at the same time.
 

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I had a similar problem after completely rebuilding my braking system. I could not get a rear pedal that would last. I could pump it up and it would hold for a few minutes then the next time I hit the brake there was little to nothing. I bled the system over and over but with no success. When I would hit a bump the front caliper would rattle around a little which was very annoying but that was a clue that the front left caliper was not fully bled. There was some slop in the mechanism due to air being in the piston. Finally one day I disconnected the front secondary MC plunger from where it attaches to the caliper. I then manually stroked the plunger over and over until I finally felt some resistance. I then followed the bleeding procedure in the book for the rear caliper. Worked like a charm. Me thinks that there is a little pocket where air gets trapped in that front LHS MC and you need to really move that piston to get it out. Once its in the lines it bleeds out easily. I now have excellent brakes.
 

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(y)
I think Porky has nailed it. My BB has always been a two person job to bleed the fork mounted master cyl.

One on the fork and the other on the caliper out back. Perfect pedal.
 
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I have 97’ seriously thinking about de linking.
I like linked also,but lets be honest they suck.
Can’t help you but,would love to know as well,good luck though.🏍
I have a 98 Bird and love the linked brakes. Took me a bit of time to get used to using them for best performance but now, absolutely love them.

But agreed the lack of support from Honda is a big negative factor if and when things go wrong. That could be the time to delink for me.
 

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Discussion Starter · #14 ·
Thanks to all the members who gave very good advice. This is why I posted this problem here. Porky: I did do all the things you suggested EXCEPT having someone bleed the rear caliber while pumping the SMC. (I actually used a screw driver to lever the plunger rod up into the cylinder). Sounds like a damn good idea. I'll have to recruit some help for that but I will try it. Thanks.
 

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Thanks to all the members who gave very good advice. This is why I posted this problem here. Porky: I did do all the things you suggested EXCEPT having someone bleed the rear caliber while pumping the SMC. (I actually used a screw driver to lever the plunger rod up into the cylinder). Sounds like a damn good idea. I'll have to recruit some help for that but I will try it. Thanks.
I went through the same thing with a VFR (also linked brakes). Did the same as what porky suggested and it was perfect. Good luck to OP!
Thanks to all the members who gave very good advice. This is why I posted this problem here. Porky: I did do all the things you suggested EXCEPT having someone bleed the rear caliber while pumping the SMC. (I actually used a screw driver to lever the plunger rod up into the cylinder). Sounds like a damn good idea. I'll have to recruit some help for that but I will try it. Thanks.

I have speed bleeders all around including the clutch, they work flawlessly.
 

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Speed bleeders replace the original bleed screw.

Speed Bleeder Bleed
Screws are essential for the do-it-yourself-er that needs an extra hand when they don’t have one. Simply put, speed bleeders replace the original bleeder in your brake caliper. They contain a small ball and spring that pushes up to release the air and old fluid when you pump the brakes, and then automatically closes back down to prevent the old fluid and air from re-entering.
 
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