Bleeding the front brake??


14 replies to this topic
  • NEW2XR

Posted March 07, 2006 - 02:50 AM

#1

Fixed my broken caliper mount on my XR650R (my last post) and though I might as well bleed the brake aswell since the lever was just about pulling in to the handlebar when braking - I heard before I bought the bike that the front brake was crap, but surely not that bad! Anyway I proceeded to bleed to brakes using a non return valve on the bleeding nipple. Have pumped god knows how much new fluid through it but brake feels even worse than before - lever pulls back to the handlebar even easier which aint good. Have been getting microbubbles and some black specks in old fluid I'm pumping out.

Has anyone else had problems bleeding their brakes and is there a method to make sure its done properly? How firm should a 'proper' brake feel, ie I assume you shouldn't be able to pull it back to the bar (the lever is at full extension away from bar).

Cheers

  • frankstr

Posted March 07, 2006 - 05:21 AM

#2

It should not come back to the bar and it should be firm..
Get yourself a vacum pump to bleed the brakes with...it will come instructions on bleeding brakes....

  • jim1234

Posted March 07, 2006 - 05:54 AM

#3

I use a 12cc plastic syringe used for giving horses shots ( I steal it from my wifes stash) They're cheap. Add a little piece of vaccum hose. Fill it up with fresh brake fluid , then you hook it up to the bleeder screw. Push a little to purge the air. Open the screw just enough to open it a little,and push the fluid back up to the master cly. This will insure no air is in the system. You can do it by yourself and it's fast. You can use it to pull the air out also , it will work both ways.

  • HappyCurmudgeon

Posted March 07, 2006 - 05:54 AM

#4

Vacuum pumps work ok if you have a good seal at the bleed valve. Make sure to use thread tape on the threads of the bleed valve or there is a good chance for an air leak there. I personally prefer to use a syringe and reverse bleed the brakes, especially the front, hard to get the air out of the top bend without one. Yes, it's possible with the vacuum method; I just prefer the syringe is all.

I just put stainless lines on my “L”, the brakes feel very firm now, I do not think I could get the lever to hit the throttle without bending it.

  • HappyCurmudgeon

Posted March 07, 2006 - 05:56 AM

#5

yeah! what Jim said. *L*

  • TimBrp

Posted March 07, 2006 - 06:02 AM

#6

Get yourself a vacum pump to bleed the brakes with...it will come instructions on bleeding brakes....


This is the only way to do it quickly and effectively.

  • ewbish

Posted March 07, 2006 - 06:54 AM

#7

I use a 12cc plastic syringe used for giving horses shots ( I steal it from my wifes stash) They're cheap. Add a little piece of vaccum hose. Fill it up with fresh brake fluid , then you hook it up to the bleeder screw. Push a little to purge the air. Open the screw just enough to open it a little,and push the fluid back up to the master cly. This will insure no air is in the system. You can do it by yourself and it's fast. You can use it to pull the air out also , it will work both ways.



Yep, same way I bleed bike brakes. Works well and easy to do with one person.

Eric

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  • roadcam

Posted March 07, 2006 - 07:18 AM

#8

I tried everything I knew to bleed mine, to no avail, trying to avoid the expense of a vacuum pump, and then I bought one of those cheap little inline bleed valve thingies, its a little doodadthat has a length of plastic tubing on each end ... you just put it on, and work your brake lever to bleed it ... worked fine :thumbsup:
bought mine from Rocky Mountain, but check and see if ThumperTalk store has it, first .. :thumbsup:

  • qadsan

Posted March 07, 2006 - 09:15 AM

#9

I'm happy with Speed Bleeders on most of our bikes, cars, trucks, etc. Bleeding is quick & easy due to the check valve design.

When I'm working on someone elses bike without speed bleeders, I simply use a plastic syringe coupled to the bleeder screw with a hose and inject the brake fluid up through the bleeder screw. This minimizes the chance of bubbles and works great most of the time. If bubbles do get into the system, then you can tap the line and master cylinder to help bring them to the surface. Sometimes you need to hold the master cylinder at different angles while tapping it get air bubbles out.

edit:
I also alternate between different colors of brake fluid, which makes it super easy to tell when the system is flushed.

  • HawkGT

Posted March 07, 2006 - 09:58 AM

#10

When I put a steel braided line on my front I didn't use any pumps or suckers (damn that sounds dirty, LOL). It took FOREVER. I kept pushing fluid out--no bubbles--with the master cylinder but when the caliper nipple was closed there was no lever pressure.

Eventually I found if I just let the thing sit with the nipple cracked open (10-20 min maybe??) bubbles would start to come out. Gravity moving fluid around in there, I guess. Strange but I did eventualy get it properly bled. I did take about 5 times longer than I was expecting. I've bled lots of motorcycle brakes (no dirt bikes though) without special tools and it was never as hard as the XR. Must be the long line and some bubble loving bends or something.

Other tips if you need to bleed without a pumper/sucker: Remove the master cylinder from the bar and suspend it so the line is never higher than the master cyclinder. Tap the line and caliper with a wrench periodically to help release the surface tension of bubbles clinging to the insides.

  • scooter1100

Posted March 07, 2006 - 10:03 AM

#11

make sure you collapse the caliper pistons to rid air from that cavity before bleeding the line btw

  • CFAmD7G

Posted March 11, 2006 - 09:37 PM

#12

Still no progress? Pry open you pads and use the horse thingy. Constantly adding fluid to the master cyl is like hitting your hand with a hammer because it feels so good when it stops hurting.

  • NEW2XR

Posted March 16, 2006 - 09:11 AM

#13

Thanks to the guy's who suggested the syringe, worked a treat - not quite doin rollin stoppies at 30mph but feels much firmer and gives me plenty of confidence i'm not goin straight on at T junction!! Great tip

Cheers

  • TimBrp

Posted March 16, 2006 - 09:38 AM

#14

Get some galfer steel braided lines from Rocky Mtn. or TT shop. About a hundred bucks and well worth the money.

  • Naru

Posted March 16, 2006 - 04:04 PM

#15

Used to use a mitivac (worked like crap), then moved to one of those pricey "V-force" injectors or whatever by Phoenix industries (still worked like crap), finally found perfection with the syringe method, with some modifications. The problem with the syringe method is that when you go to refill the syringe air can be introduced into the system. To minimize this, I went to my local college "Chem store" and picked up syringes with threaded tips, threaded nozzles with on-off valves, and tubing.

This way, you attach the nozzles to the syringe, fill the syringe and prime the tubing. Then you attach the line and bleed in reverse as normal. However, once you get close to using up the fluid in the syringe, shut the brake bleeder valve and the valve on the nozzle. Then the syringe can be unscrewed from the nozzle, refilled, and screwed back into the nozzle with no air introduced. Re-open both valves, and start where you left off.

I'll post some pictures when I can. I'd assume that these parts are also available on the internet, or through McMaster Carr.





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