Brakes sticking on

[Huggy bear]

Hi, have a problem with the brakes sticking on after riding 3 or
so miles. The only way to free them off was to release pressure on the middle bleed nipple on rear caliper. Finally when I got home and it had cooled enough for me to check calipers, all calipers seem to slide ok, so removed and stripped secondary cylinder expecting all sorts of crud but seems clean inside. Where to look next or what other problems should I be looking for.
The bike is an early EFI 2000 model.

 

[Jaws]

If it is the centre nipple then you are in the right area re the 2ndry master cylinder.
Make sure the swivel at the bottom of it is well greased and moves easily..

 

[Huggy bear]

Cheers jaws will reassemble tommorrow and will double check caliper pistons and slides for smooth operation , is it worth checking master cylinders while i've got it all stripped down?

 

[Jaws]

Just a thought.. Have you checked the rear brake lever is moving freely ?
You seem to be starting at the wrong end of the system

If the pedal is moving ok then yes, worth checking the rear brake master cylinder rubbers..
A long time ago I had a spate of the buggers that were actually turning inside out.. Dunno if it was a duff batch but they did cause some really odd problems..

 

[Huggy bear]

Have now check rear brake pedal and it seems free, not that it gets used very often tend to use front brakes only unless it's raining .Have ordered new seal kit for secondary cylinder so will update when fitted and tested. Cheers for the advise.

 

[Jaws]

Have now check rear brake pedal and it seems free, not that it gets used very often tend to use front brakes only unless it's raining .Have ordered new seal kit for secondary cylinder so will update when fitted and tested. Cheers for the advise.

Yesss.. and that is often what causes the problem.
The rear brake lever is not used very often so can ( and do ! ) gum up and not move freely. But if your one is moving freely then should be fine.
I would be inclined to try an experiment before I spent any dosh
Tie the peddle up.. use baling wire or something that you can be 100% sure will not move, then go for a blat..
If you get the same issue then it must be either the 2ndry master cylinder as you suspect or the pcv or delay valve