I'm having trouble getting all the air out of my dual actuated left hand rear brake setup. I saw somewhere that it is advantageous to turn the foot actuated master cyl upside down to help, but I still have an air bubble in the sight glass. I've used the syringe, filled the system. Got lots of air out, but still that bubble. I've pressed the caliper in and pumped it up many many times, and now I can't even pump the piston back out. Any advice?
I used a small diameter piece of rubber hose to make a seal between a syringe and the bleeder on the caliper, i forced in brake fluid and heard the air get forced out the master cylinder. Still took a while to get it all out.
Okay, I think patience is in order. This is the technique I used, but after forcing 60cc's of fluid through it I thought there must be something wrong.
I run the dual actuated rear brake on a couple of bikes. The best method that I've found is to run a long length of clear pvc tube from the bleed nipple on the rear caliper right up to the front master cylinder. Keep topping up the master cylinder with fluid. Leave the bleed nipple loosened slightly & simply keep pumping the brake on the handlebars. You will see the air coming up the line with the brake fluid. Just let the fluid recirculate into the master cylinder & trapped air escapes from the line at this point. Using this method you can see the really small air bubbles come out as well. Keep doing until there is no more air coming out. The way Rekluse said to do it didn't work for me & would not get all the air out. It was a lot messier.
Funny, that did cross my mind but I wasn't sure my hose was clean enough so I didn't do it. I'll get some new hose and try it again. After all my messing around though, it's not pumping fluid.
Another go at it last night. I bought 10 feet of clear hose and hooked it up to the rear caliper. I then used a hand actuated vacuum pump and sucked a BUNCH of air out of the lines 'till I finally got brake fluid to come out without bubbles. The line is now full of brake fluid (I did top the master cylinder a few times, but it never used that much). Still the lever has no feel and will not move the caliper. I used the gravity feed method for a couple of hours and it only moved 2 inches of fluid through the line and took about half of the fluid from the reservior. There is definitely still air in the lines, in fact, I can see a small bubble in the foot master cyl window. I'm going to do some more of this tonight, but I'm still thinking this should have been easier to do.
Its your fancy schmancy expensive brake lever. Does it have any adjustment on it? I know the stock one i turned the little screw in and it seemed to help move some fluid. I think i squeezed it about 198 times then all of a sudden it came to life!
One thing I found helped after I back bled the brakes was to partially remove the plunger on the upper master cylinder. Do not remove it completely(more air) just enough to allow the fluid to completely fill that portion of the master cylinder. Then work the piston in and out this longer stroke and it will push more fluid and re-prime the cylinder. When I did my 125 it was far worse than either my WR 250 or WR 360. The newer rear pedal master cylinder seems harder to clear than the old style. One thing is if you did not buy a kit and are pressurizing the stock foot pedal master cylinder reservoir, you will probably eventually blow the sight glass out. Make sure you zip ty it very securely in place. Just what I have seen. Walt
I have your answer , KTM and husky use the same rear master cylinder , the problem is not at the top master , it is in the rear master cylinder . The problem is in the rear brake light activator. It doesn't get oil in there and gets an air lock , no matter how much frigging around you do until you get oil in that section it's not going to worky . Remove the clip from the wiring so it can spin then remove the sensor from the rear master cylinder ,it has the wires coming out of the top of the unit , use a spanner . If you can work out all the rest of what is going on , this you can work out also . I can't remember whats inside that activator but you must get oil in there .Use your foot brake pedal and pump some oil into that side , i can't remember if there is something in the bottom to unscrew or not as i said you will work it out . Once you have oil in there put the wiring bolt thingo back in place and then try to re-bleed , bingo it now will worky
Oh! Thank you for the advice on the brake light switch, I never even considered it. Update. This morning I was able to bleed the system well enough that the foot pedal has never felt better (by the way, I do have the expensive Rekluse kit, and their instructions lick a$$). I then back bled the hand actuated section and got some bubbles out of it. It now works, and applies the brake, but it's awfully weak. It takes a pull all the way to the bar to lock it. Next I will bleed out the brake light switch.
This afternoon I bled the brake light actuator. It didn't seem to have any air in it, but it was worth the effort anyway. I back bled the whole system again and still, my hand lever just isn't going to cut it. There is no air left in the system that I can tell. The foot part works great and when I push the caliper in, nothing but fresh clean fluid comes out into and overflows the top master cylinder. When I pump the hand brake, the plunger is very lazy to return. I am beginning to think that the Rekluse guy was not correct when he told me to use the stock lever for a brake, and that DOT 4 is not compatible with the mineral oil seals. I will try to scare up a rebuild kit to change the master cyl over to DOT 4. Is there anyone out there successful using the mineral oil master cyl with DOT 4? I don't want to chase my tail.
It was a while since i have done mine . But if the foot brake works fine there must be air in that hand brake line . Wind out the adjuster on the hand break all the way , then setup the syringe on the rear brake bleed nipple , crack open the nut on the hand break line before the master cylinder , fluid should flow easily out that undone nut from the brake line when pumping the syringe , after undoing the bleed nipple to pressurise the line. Next do up the bleed nipple and that undone nut as you know that fluid is moving up that line freely , next try to pump fluid out the top of the hand break master cylinder after undoing the rear bleed nipple to pressurise that line again. It should be working .Put the lid back on .You should have some adjustment with that left hand adjuster being wound out , wind it in , see if it gives you some more pressure .
Today I was able to make the thing usable, I'm going to be back bleeding it several times over the next few days, because it has produced several more tiny little air bubbles at the top MC. Just pushing on the caliper and bottoming it out, then slowly, ever so slowly pumping it back up with the hand has produced the results I've hoped for. I still wish it would lock the brake a little further from the bar, but it's definitely usable. Perhaps riding it and bouncing around with break some more bubbles loose too.
keep the hand brake lever on , close to the bars , ktms like it .maybe some air will make it's way to the top for no effort , thats exactly the way i get my ktm's front brake to work after not riding it for a while , without bleeding it . your getting there . and yes it should be easier than what your experiencing.
I finally sorted it. DId as suggested and tied the brake closed, then worked the lever slowly and worked a few more bubbles out. Rode today, it works great. Now, I'd suggest nobody ever get one of these, or run an auto clutch. It's all for sissy's and you should be a man about it.
