How to: Bleeding The Brakes

jd750ace

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Whatever size fits best, 3/16" is probably good for this brake. I have a couple sizes because some of my bikes have larger nipples (the Euro bikes). When I change my fluid, I suck most of the old stuff out of the reservoir first (no sense pumping all that through the system) and pour fresh stuff on top. That old stuff goes in the catch bottle.

I use my old hole-ey socks for a lot of things in the garage. Mopping old fluid out of master cylinders is one of them. I use 3/16 line on the standard nipple. It needs to be snug enough to take a little burst of pressure, and prevent air from pulling around the sides of it. I've found with Tygon tube sometimes I have to heat it and soften it to get it over the nipple, but it cools down to a tight fit. I put a new bleed screw in my XS when I refurbed the brakes, and only crack it about a wrench flat when bleeding. Don't have any issue with sucking air at the threads that way, but the Teflon tape is a good idea, just keep it off the tapered sealing surface at the base of the bleed screw.
 

Ketis

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I had the same issue as you with no air coming out of the line but fluid was.

I had to keep tapping the M/C and the caliper with a rubber mallet while bleeding because there was air that was stuck.
 

Maurice

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I have not seen it mentioned, maybe it was overlooked, but here's an additional tip or 2.

- the more pressure you put on the fluid the faster the air will want to come out. For example, using a vacuum bleeder open the bleed screw just a crack with 20PSI negative pressure. Air will tend to go out faster than fluid. Open more and more fluid will come out, less air. As mentioned teflon tape or I prefer silicone grease around the threads of the bleed screw for extra sealing.
- the "clamp on the lever overnight" trick works this way, and works well at that. Pull the lever, tie it like that with bars to the left (assuming front brake we're talking about), presto.
 

XSLeo

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The gauge on a Miti Vac or similar tool isn't marked in negative psi. Inches of vacuum is the markings.
So if you pump the lever to the 20 on the gauge it is 20 inches of vacuum.
Leo
 

smg65

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I have, and have used the little plastic bottle with the magnet that XSLeo shows above with many different vehicles. I still manage to spill it! :doh: It doesn't take much to yank the bottle off of whatever it's magnetically stuck to. Also, the bottle is very small. BUT... I still use it, I guess because I have it. I swear.. next time I'm getting a BIG bottle and putting it inside a cement block so it can't possibly be knocked over.
 

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ReycleBill

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I have, and have used the little plastic bottle with the magnet that XSLeo shows above with many different vehicles. I still manage to spill it! :doh: It doesn't take much to yank the bottle off of whatever it's magnetically stuck to. Also, the bottle is very small. BUT... I still use it, I guess because I have it. I swear.. next time I'm getting a BIG bottle and putting it inside a cement block so it can't possibly be knocked over.



That's not a bad idea! Just don't trip over the block and knock it over.
 

smg65

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"That's not a bad idea! Just don't trip over the block and knock it over."

Nah... the block and bottle will stay put. But without a doubt, there goes my toe, my knee, my wrist! This wrenchin' on bikes sure can be hazardous!
 

EvenmoreXS

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Bleeding your brakes is quite easy and very important. Air in the lines can cause brake fade and failure, which can result in severe injury. However, bleeding the braking system is not to be used as a "quick fix" for other problems. Proper understanding of the master cylinder and brake caliper units is paramount. Brake bleeding is normally reserved for AFTER the braking system has been overhauled and/or rebuilt. These systems work in conjunction with each other and should be serviced, properly, together. Do Not overlook one for the other. Though separate, these units should be treated as one.
NOTE: Read manufacturer's suggested DOT fluid rating and NEVER mix two different types of brake fluids. If you plan to bleed your brakes, bleed them entirely and replace fluid from a new, unopened container. Only use brake fluid!! Not oil, not hydraulic fluid, ect., only brake fluid.
Brake fluid is a dangerous substance. DO NOT let it come into contact with painted surfaces. Immediately clean up any spill and wash hands thoroughly. Keeping a "more than normal" clean area when working with brake parts is very important!
Makes sure you read this in it's entirety and thoroughly before beginning.

This will cover the standard procedure for bleeding brakes. Both vacuum bleeding and "oil can" bleeding is covered at the end of this tutorial. Ok, lets begin.

First, read what type of DOT rated fluid you will need. It is on the master cylinder (m/c) reservoir cover or in your motorcycle owners manual (mom).
View attachment 10182

Next, you will want to reset the brake m/c position. When you open the m/c fluid will spill everywhere if the m/c is not level.
View attachment 10183

Place the bike on it's center stand and/or level the machine as much as possible. Using a 10mm socket, loosen the bolts enough to move the m/c level, slighty retighten to hold it in place.
View attachment 10184

Now, remove the 4 bolts that hold the m/c cover on. Note: I have replaced my original bolts with new, stainless steel M5 / 3mm, tappered allen head. The originals will strip!
View attachment 10185

Check the fluid level of the m/c and clean it out if necessary.
View attachment 10186

Find a sutible container to hold brake fluid in.
View attachment 10187

The object of bleeding the brakes is to remove air from the lines, thus you want to push fluid thru, and out of, the system. To do this you must attach one end of a tube, preferably clear, to the bleeding nipple...
View attachment 10188

...and submerge the other end in a container full of brake fluid.
View attachment 10189

This will allow air to exit the caliper and be forced under the fluid level. Since the end of the tube is submerged, air can not go back into the system once the tube is full of fluid. Try to keep the end of the tube submerged under the fluid level. If the tube comes out it is ok, just make sure that the fluid does not flow back into the system, bringing air with it. This can be avoided by tightening the nipple during the bleeding process.

4 step process here. 1) You will be pulling the brake lever in. 2) opening the bleeding nipple and pumping the lever. 3) retightening the nipple (just snug). 4) Releasing the lever.

So, using a 5/16 wrench, pull the lever in...
View attachment 10190
...and open the nipple. Do not completely remove the nipple. Just "crack" it open enough to allow fluid to flow out. Pump the lever a few times. The tube will fill with fluid and go into the container. Again, try to keep the tube submerged and do not let the fluid fall back into the caliper letting air in. Make sure you have fluid in the tube at all times. This will insure fluid does not flow back in followed by air. NOTE: Because the tube is on the nipple you will need to use the open end of the wrench. Opening the nipple with the wrench, with the tube on, is a pain, but after a few times it becomes easier to work around.
View attachment 10191
Then tighten the nipple while holding the lever in and then releasing the lever. Since the nipple is on top of the caliper, and the tube needs to curve down, tightening the nipple each time prevents fluid from falling back into the caliper and letting air in. It also keeps you from having to constantly pump the lever in order to prevent air going back in. Believe me, you will understand once you do this.
You will need to do this several times.
You want to do a little "dance". So it's "lever, nipple, pump-pump, nipple, lever", repeat.
Pulling the lever in pressurises the system, opening the nipple lets air and fluid escape, closing the nipple keeps fluid and air from going back in (Kind of a secondary safety), then release the lever. You may want to pump the lever a couple times to push air down to the nipple.
NOTE!!!! make sure you are watching the m/c reservoir. DO NOT let it run empty. You will need to keep adding fluid throughout this process. If you let it run dry, air will go into the system and you will have to start over.

What am I looking for?
You want to get all the air out. To know when this has happened you will, 1, see no more air bubbles coming out of the nipple and through the tube. And 2, the brake lever will no longer feel "spongy". If you have to "pump" the lever to build-up pressure, air is still present in the system. Everytime you pull the lever in it should feel nice, smooth, and be the same "pull" pressure each time. Remember to tighten the nipple each time. Do not "wrench" it tight, just snug it. This makes it a little easier to manage. Especially if you have to stand up and refill the reservoir.
View attachment 10192

Once all the air is out, no more bubbles and no spongy feeling, top off the reservoir with fluid.
View attachment 10186
View attachment 10193

Then put the cover back on and tighten the bolts.
View attachment 10185

Collaborative article written by members of XS650.com / 2011





With dual front disk's, I can still do this using one nipple, right. I don't have to do both sides… Same system and fluid… Just do one side.

Right….
 

I am Carbon

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With dual front disk's, I can still do this using one nipple, right. I don't have to do both sides… Same system and fluid… Just do one side.

Right….

I think it is a good idea to bleed both calipers.
I bleed the one with the banjo farthest out first if they are stacked.
I don't know if it makes a difference
 

Brian902

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I've used them and they work okay. Found you need to put just the right amount of sealant on the threads to keep from sucking air back into the brake fluid and stop the leaking form the thread area of the screw.

Would try pipe wrap and lots of it the next time as I find the thread clearances seem real sloppy on all bleed screws.
 
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