Can not seem to bleed front brakes 1975 xs650

[JNizza92]

little bit of background. Just rebuild the bike, new lines, no fluid in anything.

This is the master cylinder I have:
http://www.mikesxs.net/product/08-0255.html

I have been trying to bleed these brakes for 2 days now, today I spent 2 hours trying to get them to bleed. (first using the pump brake, loosen bleeder screw, pull brake in, tighten screw, pump, repeat.... and then using the bottle method (submerging a tube in a bottle of brake fluid, opening the bleeder screw and then pumping away))

Every time I pull the lever in I also get a little bit of a black hazey "smoke" like substance that appears in the master cylinder reservoir. This smokey substance comes from the breather hole in the master cylinder (the very tiny hole). I took the MC totally apart and made sure all the seals and everything was intact, and it was. Still does it though. I am stumped.

I can not seem to get these brakes bled. Every time I crack open the bleeder screw and pull the lever in I just get a tiny amount of fluid to come through, my pads are not moving in at all, they can wiggle between the rotor and caliper piston.

Any help would be appreciated, I think I am going to try forcing the fluid up from caliper to the master cylinder next.

Thanks,
Jordan

 

[Royboy]

Try putting teflon tape on the threads of the bleeder screw. It will keep air from leaking around the threads and breathing back into the caliper. Works for me.

roy

 

[gggGary]

Is that tiny hole open? It is very small by design but does have to be open. There have been a few guys who bought a mikes MC and that hole was not open. There is an excellent how to on bleeding brakes by littlebill in the tech section. It gives several techniques that it sounds like you haven't tried yet.

 

[1974jh5]

Another method I've used on stubborn brakes is this: first, wrap any painted area below the master cylinder with plastic to keep brake fluid from gettin on it. Now use a box end wrench to loosen the banjo bolt on the M/C and squeeze the lever. While holding the lever, snug the banjo bolt back down and release the lever. You'll need to repeat this until you get fluid spray from the banjo bolt (that's why the plastic wrap).

Then repeat this at the bottom banjo bolt, the one on the caliper. Once that is done, now it's time to bleed the caliper in the usual way. Yeah, this is a PITA but sometimes it's the only way.

It's also possible to reverse bleed the brakes using a turkey baster. It works like this: put a rubber hose on the end of the baster, put the other end on the caliper bleed screw. Take the M/C cover off, again it's a good idea to put plastic over painted stuff. Loosen the bleed screw, fill the baster with fluid and squeeze the bulb to force fluid through the caliper, up the hose and into the master cylinder. This may take several squeezes, to keep fluid from being sucked back into the baster you need to snug the bleeder screw down before letting go of the bulb.

If you can get access to a big syringe they work great for doing this, it's easier than the turkey baster. It also helps to wrap some Teflon tape around the bleed screw threads, you don't want it on the tapered seat though. You can even use the syringe to create a vacuum that sucks fluid from the master cylinder down to the caliper, although that means you have to be careful about keeping the M/C full. That's easiest with 2 people, one on the syringe and the other adding fluid.

 

[bpeckm]

I second the large syringe, use it to force fluid/air up from the caliper. The tricky spot is getting the air out of the top of the line, where it goes into the m/c. Once you have the line full of fluid from the bottom, and fluid in the m/c, crack the outlet fitting and try to force out any air bubble there.

Good luck, it really is a pita...!!

 

[essexboydave]

I had the same problem with my GSX1400 and what I did there was turn the bars to such a position that the master cylinder was as high as I could get it, pull the lever in to the bars, tie it there and leave it overnight. The tricky bit comes the next day as you need to remove the master cylinder top then slowly release the lever. By gently, and I really mean gently, just pulling the lever in a touch and releasing it a couple of times it dislodged an air bubble that must have been lurking at the top of the pipe, after that the brakes bled easy
A word of warning here if you have a big airbubble there as it comes up it can cause brake fluid to fly out of the cylinder so remove the tank and cover the clocks first

 

[retiredgentleman]

You're all making brake bleeding seem like a hard job, when in fact its very easy on a motorcycle. You're not dealing with long lines that are fixed to a car frame. Motorcycle brake lines are short and portable. Don't install empty lines onto the bike and then start to fill .

I place my new brake line on the bench, and form a "U" shape, such that each of the 2 ends are raised higher than the centre. Now you need a syringe with a small needle that will fit into the hole in the banjo bolt. I just use an old syringe that I had for filling ink jet containers. Syringes are likely available at drug stores.

I draw new brake fluid into the syringe and then insert the syringe needle into one of the banjo bolt holes and pump in the fluid. Repeat this until brake fluid comes out the other end's banjo bolt. So, now you have a brake line that is full of brake fluid, and none of that nasty air.

Use the syringe to pre-fill the caliper.

Here's where you need your riding buddy/ wife/ significant other, to help out. Have them carry the brake line over to the bike, and lower the line down to the caliper, keeping both ends level so that no fluid runs out onto the floor. If you're carefull, you can even do this step by yourself (temporarily plug the one banjo bolt so as to prevent air entering and loss of fluid). Connect one banjo bolt to the caliper. Raise the brake line up to the M/C and connect that other banjo bolt. You now have a caliper and brake line mounted, and guess what, they are full of fluid, with no air present.

This is the time to fill the M/C. Use a plastic hose on the caliper bleeder screw, and give a few pumps of the hand lever, to confirm you are only getting fluid and no air is present. You will have a hard lever in almost no time at all.

This takes a lot of words to describe, but its actually very simple to do. About a year ago, I installed Brembo calipers, front and rear, complete with 2 new braided steel brake lines. I used the method above, and there was almost no hand pumping of the brake lever/pedal required...................why would there be...............you are starting with lines/calipers that are full of fluid.

 

[XSLeo]

I have found on stubborn bleeding, I unhook the line from the master cylinder. I then place my fingertip over the hole where the line hooks. I then slowly pump the lever. As you pump the lever fluid pushes air out past your fingertip, your finger tip seals the air out as you release the lever. Do this untill you get fluid squirting out past your finger. You need to be sure the M/C is bled before you can bleed the rest of the system.
Now attach the line. Move down to the next joint in the line. Use your finger tips to seal the line. Pump the lever till you get fluid at this joint. Now work your way down to the caliper. Holding the line above the M/C or last place you bled, so the fuild gets pushed uphill helps.
Filling the lines on the bench as RG suggested is a good idea.
Leo

 

[JNizza92]

I filled the line, the caliper and the master cylinder. tried to bleed again, no change.

I then tried to leave the bike sit with the lever pulled over night. tried to bleed again, no change.

I tried to bleed each individual part, tried to bleed again, no change.

I tried the syringe method, this one worked slightly.... I used the syringe to push fluid up through the system from the bleed screw. I had brake fluid squirting out of the master cylinder with no air bubbles. I then shut the bleed screw and the lever had a good feel to it, but the pads were still loose between the rotor and caliper piston... so I then tried to bleed the brakes yet again, and now I am right back where I started....

Could my caliper be frozen up?

 

[cleoncleon]

I filled the line, the caliper and the master cylinder. tried to bleed again, no change.

I then tried to leave the bike sit with the lever pulled over night. tried to bleed again, no change.

I tried to bleed each individual part, tried to bleed again, no change.

I tried the syringe method, this one worked slightly.... I used the syringe to push fluid up through the system from the bleed screw. I had brake fluid squirting out of the master cylinder with no air bubbles. I then shut the bleed screw and the lever had a good feel to it, but the pads were still loose between the rotor and caliper piston... so I then tried to bleed the brakes yet again, and now I am right back where I started....

Could my caliper be frozen up?

I was about to say that...
My first time trying to bleed some stock brakes, my caliper piston was frozen :/
You should accutally be able to free it with compressed air, or just hooking it back up to the system..
Sometimes that works..

Are you sure your master cylinder plunger and such is working okay?
Disconnect the main hose, drop some oil in the reservoir and squeeze away.. just to make sure your problem isn't starting there.. you may have done this already, but, just incase..

 

[retiredgentleman]

I filled the line, the caliper and the master cylinder. tried to bleed again, no change.

I then tried to leave the bike sit with the lever pulled over night. tried to bleed again, no change.

I tried to bleed each individual part, tried to bleed again, no change.

I tried the syringe method, this one worked slightly.... I used the syringe to push fluid up through the system from the bleed screw. I had brake fluid squirting out of the master cylinder with no air bubbles. I then shut the bleed screw and the lever had a good feel to it, but the pads were still loose between the rotor and caliper piston... so I then tried to bleed the brakes yet again, and now I am right back where I started....

Could my caliper be frozen up?

Anytime you buy an old bike and are uncertain of its history, you must take the calipers apart to be certain they are clean inside, and pistons are free to move.

In other words, assume the caliper is frozen until proven otherwise.

 

[mrtwowheel]

I pump the brake lever about 10-20 times and then open the bleed screw while still holding the brake, I release the brake only when the bleeder screw is tight. About 4 or five of these and you should start feeling pressure, keep working and it gets better. You are definitely pumping and releasing at the WRONG TIME. Teflon tape on the bleeder screw threads stops air from being sucked in too.

Scott

 

[peanut]

great advice here .
I suspect that some forget to thoroughly wet the piston and seals before insertion into the MC which could definately make the piston stick and not return properly

 

[gggGary]

RG has it; no sense bleeding a brake if the caliper hasn't been apart. In Michigan it's a near certainty you will have one or both pistons badly rusted. Water is heavier than brake fluid and settles to the lowest point in the system.

 

[dude-ler]

One last thing. After you've had it apart (pops right out with a shot of compressed air) push the piston all the way in. Minimize the amount of air you have to deal with.

 

[gggGary]

One last thing. After you've had it apart (pops right out with a shot of compressed air) push the piston all the way in. Minimize the amount of air you have to deal with.

Put in some brake fluid THEN push the pistons all the way in. Use rags etc to catch the excess fluid.


you will probably find it's cheaper to buy a replacement caliper than 2 pistons. And they may NOT come out with compressed air, the northern rust can be tough stuff.

 

[JNizza92]

Ok, I will continue in my quest for the caliper tomorrow. I will tell you that it did work last summer, but this winter when I started the overhaul I pushed the pistons all the way in (they did not go easily). So I know they did move, but I am thinking that they are now stuck in. I will focus on the calipers tomorrow. The fedex man is bringing me a mityvac tomorrow too

 

[essexboydave]

I have had similar trouble with my XS recently. Before I bought the bike it had been sat outside for over 3 years and the front brake was very sticky so first off I tried the old trick of just pushing the piston back as far as it would go then pumping it out again and bleeding it which worked just well enough to pass the mot (that's our annual roadworthiness check) but within a mile or so it was sticking again so I stripped and cleaned the caliper and then it just wouldn't bleed. It turned out to be the master cylinder that was the problem and when I changed that it bled easy as anything, I guess the seals in there must have been right on their last legs when I bled it the first time!

 

[glennpm]

The best way I've found is to suck the brake fluid through the bleeder, nice and controlled without getting brake fluid all over your nice paint and disks. Get a Mityvac or a Harbor Freight version, http://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-69328.html

First fill your MC, slightly loosen the bleeder, slip your box end wrench over the bleeder so that you can swing an arc from closed to open, slip a clear plastic hose over the end of the bleeder which is then connected to the brake bleeder, pump to draw a vacuum and then crack the bleeder open. Keep doing this until you see solid fluid with no bubbles. Make sure that you keep fluid in the MC.

When you're done, leave the brake handle depressed overnight by tying it off with a rope, bungy, etc. This will get rid of the last of the air bubbles.

 

[member3480]

I bought three from Mikes and all did the same thing would not bleed. So after i bought one from someone else i took one apart and found that it would only bleed if i took the lever off and bleed it that way. Looks like the plunger stays open with the lever on and sucks air. After i bleed it that way it worked and i took a little off the lever so it didn't hold the plunger open. It may just be the wrong levers on them from factory because all three worked fine after i made the adjustment. You buy new and just hope it works.