Rear master cylinder

[onethumb]

Hi all I'm getting close (again ) to finishing, working on the electrics at the mo and in between sorting other bits out. This is where I've come across a problem with the rear master cylinder, it was seized when I bought it but I freed it up and all the rubbers were nice and soft so thought it was sorted, then on putting fluid in today it wouldn't bleed in fact nothing was goitre through so I stripped it again and I now think that the spring has lost its power has it's not returning well and seems to be soft. Is this something that is common with seized brake cylinders, is there something I should do or do I just need to buy a new kit?
Thanks.


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[Bryanj]

Masters frequently need priming to bleed as they air lock and will not push fluid.

(1) WEAR PROTECTIVE GLOVES
)2) cover any painted item
(3) disconnect outlet pipe
(4) put gloved finger over outlet hole and push down pedal
(5) remove and replace finger with pedal down
(6) with finger in place release pedal

Repeat (4) through (6) until brake fluid squirts out around finger under pressure
and

Finally, with pedal down reconnect outlet pipe and bleed to caliper

[onethumb]

Masters frequently need priming to bleed as they air lock and will not push fluid.

(1) WEAR PROTECTIVE GLOVES
)2) cover any painted item
(3) disconnect outlet pipe
(4) put gloved finger over outlet hole and push down pedal
(5) remove and replace finger with pedal down
(6) with finger in place release pedal

Repeat (4) through (6) until brake fluid squirts out around finger under pressure
and

Finally, with pedal down reconnect outlet pipe and bleed to caliper

Thanks for the tip. I'll give that ago later today.


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[onethumb]

Hi all, been a while. Struggling to find time at the moment.
After trying this method for an hour I gave up and ordered a new seal kit. Turns out the seals had all expanded. New seals in took no time at all. To help others on here the rear master cylinder kit is the same as a cb750 dohc 1980. Got a new one from the bay for £20. Happy days.



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