Weeping front master cylinder

[VladTepes]

After a ride a small amount of brake fluid seems to be weeping from the top of the front brake master cylinder.

I have tried removing the top, checking the rubber seal and refitting, making sure screws tight etc - doesn't seemed to have helped.

I can only assume then that it occurs when under pressure when brakes are being applied regularly. It doesn't seem to be the case when its just sitting overnight.


Thoughts?

[grog]

No leak from mine. New seal required im  thinking.

[Blubber]

Could it be that the reservoir is overfilled?

If so... there will be no room for expansion in the reservoir and it will overflow

[Hooli]

The rubber seal should stop it leaking even if it's overfilled.

Clean the top edge of the reservoir and the underside of the cap, including the two tiny slots at the sides for it to vent.

[GSXKING]

Check the level Mike. Have you done anything recently i.e. changed pads etc. ?

[Notty]

I over filled mine after new pads it only weeped occasionally 

[froudy]

If as already mentioned you've had the cover off recently for any reason, then they do tend to weep a little. Wipe it over and see if it comes back. If it does, then you'll need to investigate further.

[Eric GSX1400K3]

Too full.  Bleed the system a lever pump or two at the caliper and should be all good. Resevoir cover off of course.

[Hooli]

Just suck it out with a syringe, even easier.

[gsxbarmy]

I agree with all the above - its either slightly overfull or not pulled down flat and the rubber seal is not flat. First off I'd take the cover off, take out the plastic insert and the rubber seal wipe them both down. Also with the handlebars level, just check the fluid is not above the marker within the master cylinder (yes there is one, a small mark in the alloy) - then refit, nipping up the screws on the lid. If it still weeps nip it some more. Can take a couple of goes sometimes.