Leaking master cylinder - Wrist Twisters
 
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post #1 of 9 Old 10-04-2013, 08:19 PM Thread Starter
(Quintus) Pilus Prior
 
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Leaking master cylinder

So I put on renthal mediums a few months ago, and rotated the controls forward a little. At the time I also bled the brakes and had to flip the upper banjo back as I'm pretty sure the precious owner flipped it for more clearance with the urban machinery bars on the bike when I got it. The problem is I've noticed the last two weeks or so my brake fluid has been pretty low, like almost emptying the window during braking. Could be that the front end is starting to dive a little more, or could be it was always low and I'm just noticing it now, but I'm almost positive I filled it up last time. I figured I'd take a look today when I was wrenching and sure enough it was about halfway down. So problem one is where the hell is the fluid going? I checked all the joints etc and nothing is jumping out at me. So I threw it on the center stand, put a block under my front wheel to make the master cylinder more level, and filled it up. Now that I've put the cover back on problem number two is the fluid is weeping out the front of the bottom of the cover. Not sure if it's just a little that got smushed out when I put it back on, but I spent a half hour wiping and walking away and wiping again and it keeps coming back... And brake fluid is not fun stuff to be leaking...

Tl;dr
So 1 is where could my brake fluid be going, and 2 is the master cylinder cover supposed to be leak proof? Or if it's at an angle during normal riding should I have the level accordingly lower?

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post #2 of 9 Old 10-04-2013, 08:35 PM
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When I've bled and refilled once, I had the same issue with the leak around the top of the reservoir. Tightening the screws didn't help and they're probably in need of replacement next time I redo them again. To stop the leaking, get it level like you had and make sure the rubber pieces inside are CLEAN! Wipe em down and make sure there are no debris. Mine looked clean but after wiping and placing them back on, no leak.

I should add that when I put the screws back on, I went to just shy of snug on each side first, then snugged each sided, then torqued down.

As for losing the brake fluid...not sure. You certain you checked all around including the caliper side? Brake fluid will usually leave marks on stuff it gets on, specially paint.

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post #3 of 9 Old 10-05-2013, 12:08 AM Thread Starter
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I took it back apart and cleaned the seal really well and dropped the level just a fuzz and it's been dry for a few hours now, so it looks like it should be good.... Now we'll have to see if it mysteriously disappears again...

Love is the feeling you get when you like something as much as your motorcycle - Hunter S. Thompson
I just mı̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̨ade you wipe your screen.
-2009 Suzuki GSX-R 750 Race Bike
-2007 Honda 919
-1995 Nighthawk 750 (Tboned)
-1983 KZ 440 (Sold)
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post #4 of 9 Old 10-05-2013, 04:51 AM
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I have had the same issue before too. Just taking the cover off and re-seating everything and putting the cover back on stopped the leakage.

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post #5 of 9 Old 10-05-2013, 10:10 AM Thread Starter
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It sat overnight and still looks dry... I guess it just wasn't seated right... Thanks for the help!

Love is the feeling you get when you like something as much as your motorcycle - Hunter S. Thompson
I just mı̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̨ade you wipe your screen.
-2009 Suzuki GSX-R 750 Race Bike
-2007 Honda 919
-1995 Nighthawk 750 (Tboned)
-1983 KZ 440 (Sold)
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post #6 of 9 Old 10-05-2013, 01:12 PM
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sounds pretty typical those master cylinder cap seals can be finicky some times.

Also note as the pads wear down the pistons stay further out using more fluid... this is why over time fluid level will drop. That stated fluid level should not drop significantly in a short period.

Proper filling of the master cylinder is have the master cylinder level, and fill to just below the line (ridge) that runs around the inside of the reservoir... the little ridge above the site window.

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post #7 of 9 Old 10-05-2013, 01:22 PM Thread Starter
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Will it cause a problem if I fill it while level and it's not level during normal operation? Other than just needing to remember to have it level when I open it again?

Love is the feeling you get when you like something as much as your motorcycle - Hunter S. Thompson
I just mı̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̨ade you wipe your screen.
-2009 Suzuki GSX-R 750 Race Bike
-2007 Honda 919
-1995 Nighthawk 750 (Tboned)
-1983 KZ 440 (Sold)
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post #8 of 9 Old 10-05-2013, 01:29 PM
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No, it wont be a problem


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post #9 of 9 Old 10-05-2013, 01:32 PM
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Quote:
Originally Posted by badmoon692008 View Post
Will it cause a problem if I fill it while level and it's not level during normal operation? Other than just needing to remember to have it level when I open it again?
nope. just get it as level as possible (should be pretty close if you put the bike on the kickstand and turn the bars full lock right) and fill her then cap it back up.

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