Bleeding Brakes. Possible air in my system?

[Ken]

I decided to bleed my front brake after the Woodcraft Clip-ons installation. I've done it on cars dozens of times however this is my first time doing it on a motorcycle.

I' did the following: Hold the brake lever down, crack open the brake bleeder, then tighten the bleeder while the brake is still applied, then release. During this whole time I always make sure the reservoir is always full to prevent air getting sucked into the system.

After I sealed everything up I noticed bubbles weeping out of of the master cylinder cap. Below is a vid:



Is there air in the system? Did I overfill or underfill the reservoir?

When I apply the lever it feels firm like before.

When I apply the brake lever as hard as possible I can get the lever to touch the grip. Can someone try it on their bike and let me know if it's normal? I didn't do it beforehand so I don't have a baseline. Thanks for any advice.

[kkim]

bubbles don't seem right. is there a gasket under that cover? if so, maybe the gasket wasn't put back on correctly?

on the other hand, when i did my clip on install and moved the brake res out of the way, I did get some weeping out of that little hole. i don't get any when it's fully mounted and I squeeze the lever, though.

[Ken]

Yes,

The gasket is stuck underneath the lid. I wiped everything clean of debris (the gasket, the mating surface) before I screwed the cap down.

[kkim]

I'll take a look at mine after I get home from work in about an hour or so.

Like you said, maybe an overfill (if that's possible). can you see any air at all when you look in the reservoir sight glass?

[Ken]

Originally Posted by kkim

I'll take a look at mine after I get home from work in about an hour or so.

Like you said, maybe an overfill (if that's possible). can you see any air at all when you look in the reservoir sight glass?

There is no bubble in the sight glass.

I pulled off the cap again and pulled on the lever. I see no bubbles coming from the drainage hole when I squeeze the lever repeatedly, but the force from the release pushes fluid up and out of the reservoir. I'm thinking I've put too much fluid in the reservoir.

After dinner I'll siphon some fluid from the reservoir and seal it up and retry.

Thanks for your assistance Kelly. If you can, please check your lever for me to see if yours can touch the grip if you try really hard.

[kkim]

Okay, I get home and I'm sure I won't see any fluid come out that hole and what happens?? I pull the lever and a small bit comes out the little weep hole. I wipe it and try again, but no more comes out no matter how many times I pull it. I guess fluid gets up in there when the reservoir is tilted or when you ride and some gets expelled from the fluid moving back and forth in there.

So, it must be like a "vent" so when the fluid level drops as the pads wear, air can get in there and there won't be a vacuum. It does sound like you might have too much in there. I'd take some out so you can see some air at the very top of the sight glass.

I tried to squeeze the lever to the grips, but it won't do it. I guess I could if I really hammered it, but in real life if I pulled that hard on the brake lever, the front wheel would be locked up.

I don't know if it makes a diff, but the hole on my cover is on the other side, towards the outside of the bike as opposed to yours which is towards the inside. Did you perhaps rotate that cover around? Like i said.. i don't know if that makes any difference or not.

[Ken]

Kelly,

I guess I put a little too much fluid. I put the cover back the way it was before (the text on top of the cover should be readable from the rider's seat) and it doesn't weep any more.

Yeah I have to do a death grip to get the lever to contact the clip-on otherwise it's very firm with a "normal grip".

Thanks for your help in insight!


Can't wait to try out the new riding position tomorrow!

[kkim]

how does the bike feel now with you sitting on it in the garage and making vroom, vroom sounds?

[watcanido]

I'm no expert but I think its not supposed to leak out fluid like that. check if you have the lid and the rubber aligned properly. It seems like it has air bubbles in there still, if you can get a brake bleeder kit or a plastic tube try bleeding the brakes again. Good luck

just curious which DOT brake fluid did you use?

[Ken]

Kelly: I borrowed my friend's '07 ZX-6R for a few weeks straight and on that bike you are really leaned forward reaching low because the seat is almost as high as the clip-ons. When I rode that bike I wished the clip-ons were closer and a little higher. Sitting on my bike with the clip-ons it similar to how I wanted the ZX-6R to feel.

When I actually start rolling with my feet on the pegs I'll know for sure whether I'll like them or not. I better like them because I don't feel like spending more time returning it to stock.

Jhaqui: Thanks for your reply. I took out a little bit of fluid and it no longer weeps. I'm using Prestone synthetic DOT 3 brake fluid.

[Alex]

Originally Posted by 310ken

I'm using Prestone synthetic DOT 3 brake fluid.

Why did you go with DOT 3? Our manual specifies DOT 4 (page 2-12 of the service manual). DOT 3 and DOT 4 can generally be mixed without any huge problems (unlike DOT 5, which can be mixed with anything else safely), but I don't see any advantage to going with the DOT 3.

[Ken]

I used it because I had a couple of unused bottles.

[Buffalony]

Originally Posted by Alex

Why did you go with DOT 3? Our manual specifies DOT 4 (page 2-12 of the service manual). DOT 3 and DOT 4 can generally be mixed without any huge problems (unlike DOT 5, which can be mixed with anything else safely), but I don't see any advantage to going with the DOT 3.

+1

There is a DOT 3 or 4 fluid on the maket since we are on the subject.

Did you try bleeding the line some more cause it sounds like your getting a motorcycles version of a spongy brake.
Generally you need to open and close the valve a few times to work out all of the air in the bottom half of the line. Under pressure the air is going to go in the direction of the closest exit. Also, close the valve while the brake lever is in movement. I'm assuming you know all of this cause you've done brakes before, but brake jobs are far and few for most. So maybe you got something useful out of this.

Does anyone know if the master cylinder is supposed to be full or just to the window? I think it doesn't matter as long as theres some in it.

[Ken]

I know I should have RTFM, but the master cylinder cover does say DOT 3 or 4.



But for shits and giggles I'll flush it out today with DOT 4 stuff.

[sometimesido]

Funny, but somewhat related story.
I was flushing my brake fluid yesterday(3 years) and my front brake lever was just too easy to squeeze. Long story short, after the the outer cover and inner plastic cover, there was another rubber cover inside the reservoir.

[Buffalony]

page 116 of the owners manual.
Fluid Requirement
Use heavy-duty brake fluid onlyfrom a container marked DOT4.

Fluid level inspection
The brake fluid level in the front brake fluid reservoir must be kept above the line (lower level line) next to the gauge.

Page 117 Shows an uncapped front brake reservoir and points out the upper and lower level line in it.
Read the manual before doing your own maintainence.

Here is a good link for everyone in general.
http://www.carbibles.com/brake_bible.html

There is a section in there explaining the brake fluids under D.O.T. Ratings. good stuff

[Ken]

Bled out my brakes with DOT 4 fluid.

Bike rides great with the Woodcraft Clipons