HI, all.
just some advice would be greatly appreciated on this one, currently restoring, nearly there, 1997 blackbird, and having had a complete nightmare with combined brake system I have finally managed to build up pressure and get the rear working properly. after a 2 successful bleeds of the system, one with a vacuum and one by hand, and a replacement rear master. I have a noise coming from the front of the bike when pressure to the rear pedal is applied and eventually pressure at the pedal drops off, two pumps on the pedal and the pressure is back to normal, , every thing is as it should be and the system appears sealed properly. Is there any chance there could be some air trapped in there somewhere that is making this noise? it really is just a squeak and I would like to eliminate it before I completely rebuild the fairings etc and get it to an MOT.
thank you in advance for any help

 

Welcome to the forum Daren,

Bleeding the brakes on the Blackbird is more troublesome due to them being linked and the proportioning valve. Do you have the shop manual for your bike? That has lots of good information in it regarding bleeding as well as operational information for how it's supposed to work. Knowing how it's supposed to work is half the battle.

 

hi, thanks for the welcome, and your reply. In short, yes I have studied it extensively and followed the advice on here for the bleeding procedures, even downloaded full schematics so I could see how the system works, I just can't seem to place this squeak, I can only assume there is some air in one of the junctions at the front, the secondary master is working fine and applying pressure for the rear calliper as it should, I really wondered if anyone had had this experience also and if they had managed to cure it. it is also a little disconcerting that it may cause an issue later on which is why I would rather eliminate it than leave it lol. I did toy with the idea of replacing the system with a std brake system, but I would love to keep her original as possible.
cheers

 

I can't see "air" being the source of the squeak. It could give you a spongy feel and poor breaking. Do you hear it if you're using only one of the brakes? Does it do it when using just the front lever? How many miles or kilometers on her? How is the fitment of all the linkages, particularly between the front caliper and secondary master cylinder?

 

my thought exactly as the system appears to be air free on bleeding successfully, there are new hoses, good ridge, between all connections. everything seems to be in good order, my only possible concern is the front secondary master, which has not been replaced as was in good order and working as it should with appropriate pressure being applied to the rear calliper when comprised. I know that previous owner blew the seal in the rear brake master by pushing in the rear calliper cylinders too hard without relieving pressure on the system, which was the reason for replacement and a complete flush of the system was required as she has done 49000 miles without services until she got to me. the noise only appears when using the rear brake foot pedal. fronts are good and well bled with no sponginess. as I said rear brake loses a small amount of pedal pressure when left but soon comes back after 2 depressions on pedal kinda what made me think air somewhere in there.

 

I know that the manual says not to take the Secondary Master cylinder apart. It seems to me though that if you could somehow precisely measure it's current assembled settings, then rebuilding might be possible. The internals are available for it from Honda still. At least taking it apart might tell you if it's worn out.
https://www.ronayers.com/oemparts/a/...aster-cylinder