I've had this issue for a while, can't find any leaking fluid, weeping, etc. anywhere. The bike loses front brake pressure every week or 10 days, down to nothing, lever to bar type action. The fix is bleed air out of the top of the brake cylinder bleed off valve, then, the brakes are top notch again. It has to be an issue with letting air IN vs. oil out! Ideas?

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Sounds like you have yer answer...maybe a cylinder rebuild?

It has to be an issue with letting air IN vs. oil out! Ideas?

That was my thought too. I would first try replacing the rubber inside the fluid reservoir. If air was going to get sucked in, that would be the place most likely to have it happen. I believe that rubber doohicky acts as an air displacer and prolly also a gasket for the screw on cap. You are supposed to replace it every 3 years or 6K miles(check manual on those periods). I have 30K on mine. I don't know ig the rubber has been degrading all along or it is more recent but I am going to change it soon. If the rubber is coming off, there will be a hole eventually.

this is after most of the crap got sucked down the tube to the MCylinder.

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Donny, I distinctly remember that rubber thing was pulled down into the cup one time when I bled (brakes it was but same idea) as though it was sucked down. Nothing else would cause that. I'll bet there is a reasonable amount of suction happening up at the top of the reservoir cup.

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I don't think any air can get into that line from the res...UNLESS...you suck the fluid down so low it allows a bubble to get in there...but...that's kinda doubtful IMO...the fluid doesn't GO anywhere just sitting in there pumped up and ready to work.It's not like the fluid is running through the line somehow...and air 'just happens' to get pulled along with it.The bubbles are gonna go UP...not downward.I think the master at the perch is having and issue...OR...maybe your nipple there,or at the bottom on the slave..OR...the calipers up front nipples.You didn't overtighten those babies at some time did ya?.If it sucked in at the bottom...it would eventually make it's way to the top master bleed valve.If the line was damaged..you'd see fluid SOMEWHERE...so it doesn't sound like it's a line.And you didn't say IF your res was losing fluid...did you?If not...it HAS to be the nipple(s).OR the master up top wearing out(the rubber seals and such).There's air in that master coming from somewhere though....

* Last updated by: Grn14 on 5/6/2012 @ 2:39 PM *

I don't think any air can get into that line from the res...UNLESS...you suck the fluid down so low it allows a bubble to get in there..

Yes, that's true.

OR...maybe your nipple there,or at the bottom on the slave..OR...the calipers up front nipples.You didn't overtighten those babies at some time did ya?

Are we still talking about brakes or has the topic turned to titty twisters?

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Nipples man!We're talkin NIPPLES...you know...like mini volcanoes.Those kind!!!!LOL!He already got his answer

Thanks, will be taking care of this! Good ideas!

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