rear brake problems cbx 550 82: which mastercylinder?

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8alessio4
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rear brake problems cbx 550 82: which mastercylinder?

Post by 8alessio4 »

Hello everybody,

I am writing from Italy.

I have an '82 cbx 550 having some troubles with rear brakes.

The brake remains "blocked".

I changed oring and pistons and I driven for at least 400 km without any problem.

Today the brake is once again blocked: it happens when driving in traffic for a few times and all the system is quite hot.
Maybe pushing for a few seconds the rear brake it remains "blocked".

Do you suggest to change the mastercylinder?

It seems hard to find the correct one, anyone may help me?

Sorry for my english.

Regards
Alessio from Rome Italy

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NobleHops
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Re: rear brake problems cbx 550 82: which mastercylinder?

Post by NobleHops »

Alessio,

On the side of your rear brake master cylinder there is a small plate that the hose from the reservoir goes to. Remove it (it will make a mess, be ready). Inside there are two small holes that feed brake fluid into the master cylinder, one is the supply and the smaller one is the return. The smaller one is probably blocked.

Take a wire brush and pull one piece of wire from it. Hold it in a pair of pliers and then use it to clean out the hole. That might fix your problem if you find it was blocked.

If you do find it blocked It would be better to disassemble the master cylinder and clean and flush the entire rear brake, but this will get you riding for a while.

P.S. We ride the six cylinder 1000cc CBX here, don't know much about the CBX550.

N.
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Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

EMS
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Re: rear brake problems cbx 550 82: which mastercylinder?

Post by EMS »

Have you worked on the rear brake caliper at all? It seems your problem may be there instead of the master cylinder. :think: :think:

8alessio4
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Re: rear brake problems cbx 550 82: which mastercylinder?

Post by 8alessio4 »

i worked on brake caliper changing them and also changing the oring.
i supposed that the problem is in the mastercylinder because it seems like the pump does not properly work and in many forums i read that if the problem remains once changed the caliper it could be possible that there is a problem in the MC.

assuming that Noblehopes is right, do i have to remove the green or the red circle?
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steve murdoch icoa #5322
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Re: rear brake problems cbx 550 82: which mastercylinder?

Post by steve murdoch icoa #5322 »

After removing the bolt circled in red[there are 2 of them] you will have access to the tiny ports that Nils was talking about.
This would only be a temporary fix and the whole master cylinder should be removed and cleaned.
Good luck.

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