Bleeding rear brake system -> Am I doing something wrong?
 

So, first off, I appreciate all the help I’ve gotten thus far from these forums. The information and helpfulness of people on here really has given a breath of new life for a lot of these bikes, that would be otherwise unsupported, so once again, thanks in advance for the clarification I’m about to seek.

The subject in question -> rear brake bleeding. Never in my life have I had difficulties bleeding any sort of hydraulic brake system until I got a couple of chinese pit/dirt bikes. So that being said, I just want to reach out, for sanity’s sake, to ensure there is nothing I’m missing in how I’m bleeding my rear brake systems. The symptoms I’m experiencing are a completely lack of pressure from the rear brake. The pistons/pads BARELY move when the rear pedal is depressed. I’ve even gone so far as to replace the brake pads, and replace the rear caliper on one of the bikes, but to my dismay, I’m still running into the same end result -> rear brakes that don’t work on either bike. Anyway, here’s what I’m doing:

1 - Hook up the brake bleed tube and bottle to the bleed nipple on the caliper
2 - Open the rear brake master cylinder to ensure that it has ample fluid in it, and close it back up.
3- Pump the sh*t out of the rear brake to build some pressure i the line.
4- WHILE KEEPING THE BRAKE PEDAL FULLY PRESSED, I crack the bleed nipple open just enough to let fluid (and subsequent air bubbles) to flow up the tube, and into the bottle
5- Close the nipple, release the pedal
6- Repeats steps 3-5 two or three times until fluid starts to get a little low in the cylinder
7- Refill the master cylinder, and start the whole process over again until no air bubbles are seen in the bleed line.

I swear to god, I’ve done this at least 10-15 times PER BIKE, to the point where no air bubbles have been seen for 2-3 cycles of this process, and still, the caliper pistons barely move at all. I’ve never had issues with the front brakes on motorcycles, but I’m starting to wonder if I’m doing something wrong as the symptoms are the same on both bikes, and for the life of me I can’t figure out what’s going on. I’m not seeing any leaks on the nipple or the cylinder, so I’m not sure where to go at this point.

Thanks again for the help!

Can you take a picture of your rear caliper for us ?sometimes you need to move the caliper in order for it to bleed corectly

I would suggest opening and closing the bleeder as quick as possible, not waiting for it to fill the tube, it will fill up the tube and bottle over time anyways, just open and close it as quick as possible.

You can also try and put a "Check Valve" (one way valve) on the hose, those have helped several times with pain in the ace brake systems

One similar to this Dorman should be small enough to fit on the tubing

http://www.rockauto.com/en/moreinfo....620275&jsn=232

Here's a link to a picture of the caliper (unfortunately, it's super close up, so it might not help too much). I can get a better picture this evening if necessary.

https://goo.gl/photos/aYxQsVFkdi8hysZC8

So, as far as opening/closing the nipple as quickly as possible, what I do is, I get the preliminary bubbles out of it by opening it a little longer to get the bulk of the bubbles out. After I don't see any more bubbles, that's exactly what I do. Basically flip the bleed nipple open/closed a few times (with the tube still attached). I also make sure that the fluid is still moving OUT when I close the nipple, so air doesn't have an opportunity to get in as hydraulic pressure runs out.

Yeah, this is stumping me. Both my bikes I've been working on pretty steadily over the last month or two, but this is the last issue I can't seem to get over. I ordered a mityvac, which I've heard works well for pulling the old fluid out of the line, although, i'm not sure how much of a difference it will make. I've also considered doing the whole "reverse fill" method with a syringe, pushing the fluid in from the bleed nipple, but I wasn't sure what the opinion was on that, and wanted to see what people here said before I pulled the trigger on any other ideas.

Try pumping it up ,then crack the banjo bolt ,see if you get any pressure there because sometimes they build up pressure on our bikes .Then once you are satisfied you have pressure and flow at the banjo fitting ,try bleeding at the bleeder screw .If you are still not winning ,remove the caliper bolts ,insert something between the pads to compensate for the brake rotor ,lift the caliper higher than the master ,and bleed it that way .Dont let the master run dry or you will be starting fresh again .

To piggyback on Bruce's comments, when you insert something between the pads and lift the caliper, rotate the caliper so that the bleeder is the highest point. In your pic, the bleeder is the lowest point, which makes it very difficult.

Air lock in the line...
motor bikes are a real bitch at times...
air travels up... Helps if the bleed nipple is the
highest part of the system...
take the caliper off put something between the pads
hold it above the master cylinder/pump while you bleed it..

Front brake... I take the master cylinder
of put it on a old set of bar , put it on the ground lower
than the caliper....

Another trick that works sometimes is to lay the
bike on it's side.... helps remove the hight diffrents...



..

bleeding foot brakes
 

What I use is a plastic syginge I fill the tube with brake fluid.. aand put a hose on the end of it... remove the top of the fluid cylinder .. if it is a sealed foot valve... if there is a bottle for a reseverse them just remove the top... crack the bleed screw and slowly force the fluid into the calipher... some times you have to have the piston pushed back all the way to get the air out and block it back ... to hold it to force the air out ... I will try to take a pic of what I say. to use.. you can get them at harbor freight... princess auto.. feed stores for feeding animals.. cheap

youtube video for brakes
 

ok... go to youtube... search this.... https://www.youtube.com/watch?v=8JRzN896Uyw or MOTORCYCLE REVERSE BRAKE BLEED.... this will show you want I said above....... works for me on all the foot brake systems...

Flashlight...this is great and useful information for the members. Thank You !