Master Cylinder- No Pressure

[Seifer]

My brake yesterday had no pressure in it so I bled them till they were fina again. Overnight they went back to having zero pressure. Bled them again this morning and 30 mins later same again. I can't see any leaks anywhere so would I be right in blaming the master cylinder first.
Anyone know where I can get a rebuilb kit from and anything i shouldpick up while i'm there. MCAS didnt have any. Saw some online for the Nissins but they were for a dirtbike. Are they the same chestnut?

[miniman1]

I'd maybe try replacing the washers first, cheaper and easier than rebuilding the m/c

[DCRacing]

i had the same issue on a race bike, but in one of the bleeds i got a small piece of rubber out when bleeding it through from the bleed screw st the MC, so i am pretty sure it is the seals collapsing, i still haven't rebuilt it yet but i would say that is the problem.

[MONO]

more info age model etc........cheers

[Jockney Rebel]

hydraulics is my game ..master cylinder seals are the most likely culprit when youve got it in bits check your piston and bore for scoring

[Seifer]

Yeah mate, gsxr 1100 slingy. Its def the cylinder. The outer rubber is barely existent. I'd say the bloody thing is ancient. I'll chase up a kit at the wreckers tomorrow. Cheers.