User Tools

Site Tools


Bleeding a dry brake system in 5 minutes!

So… I just installed a YZF600 entire front brake system on my bike. Calipers/hoses from one bike and the master cyl, resovior, and lever from another. Everything was bone dry when I got it, which made it extremely hard to bleed. Until I found an insanely easy way to do it. If you've tried to bleed a dry system you know how much a pain it can be. Believe it or not, i did mine in 5 minutes. After getting extremely frustrated knowing it shouldn't take half as long as it was taking, I sat and brainstormed, and then it hit me, push the fluid up from the bottom instead of pour it in through the top. So I thought I'd share the knowledge.

I “borrowed” a syringe from my nurse friend, she laughed when I told her what I was using it for. The syringe I used is called a luer lock (or lewer lock, crap, i don't sounds like lewer), a small vacuum hose that can be stretched to fit over the bleed screw, and a zip tie if the syringe tip is too small. You can use some other type of syringe, it just has to be big enough (40cc ish) so you don't have to refill all of the time. Mine was 10cc and i had to refill it twice on each caliper.

To make the macgyver thing:

Take 6 inches of vacuum hose (borrow from a friends really, don't do it) put it on a syringe, zip-tie it on tight, and make sure it makes a tight seal over the bleed screw. Put about 1 cup of brake fluid in a CLEAN bowl and suck the fluid up with the vacuum hose on the syringe, and get ready to bleed!

Click to enlarge

How To

  1. Check tightness of all banjo bolts (brake line bolts)
  2. Start at the caliper that has the longest brake line between it and the master cyl (or “Y” splitter on the lower triple tree for the FZR) if they are the same the do whatever you like.
  3. Loosen the banjo bolt at the top of the line that comes off of the caliper (whether that be at the master cyl [YZF600] or at the lower triple tree [FZR600]):!: YZF600's have a banjo bolt that goes through two brake lines that connect at the master cyl
  4. Suck up some brake fluid in the syringe (don't suck up air bubbles, start over if you do)
  5. Tilt the hose/syringe up and push the bottom of the syringe until the fluid is level at the top of the vacuum hose.
  6. Put a 5/16 wrench on the bleed screw and leave it closed until you put the vacuum hose on.
  7. Crack the bleed screw loose, you only need 1/4 turn or so…if that.
  8. Slowly pump the fluid up the brake line until fluid is coming out of the banjo bolt you loosened, if you see bubbles at the banjo bolt, keep going until you see no more bubbles. (If you see fluid leaking out around your bleed screw threads then take out the bleed screw and put some grease on the threads for a seal.)
  9. close the bleeder, THEN take off the hose, refill if you have to, then go back to Step 4. Also use this time to sit back and giggle if bleeding a dry system has been insanely hard for you before.
  10. After you do the first side, close the banjo bolt (unless you installed a full yzf600 front brake system) and go to the other side. For the FZR you'll need to close the banjo bolt on the “Y” splitter for the side you just pumped up, leave the other banjo bolt on the “Y” splitter closed and go up to the master cyl and loosen that banjo bolt. Start at Step 4 again, do the same thing.

Once this is done, Check to see if you have enough fluid in the resovior, and fill it. Close all banjo bolts snugly and bleed the brakes like you would normally bleed them. If you don't know how to, then just pump (squeeze over and over) your brake lever 4 or 5 times, then squeeze the lever hard and open and close the top banjo bolt near the master cylinder, DO NOT let go of the brake lever with the banjo bolt or bleed screws open! Open and close it quickly, fluid squirts out, this is normal. Repeat this 3 or 4 times. Then do the same thing for the bleed screws at the calipers, you might need a second person to help you with that part. Every time you open and close the bleed screws the pressure should drop a little until you pump the lever a few times, then you should have more pressure than the previous pump. While you're doing this, glance over at the resovior to ensure you aren't getting too low on fluid when you do this. Once you've done this at the banjo bolt and at each bleed screw, you should have normal brake pressure. If you don't, then check the tightness on the bleed screws and on ALL of the banjo bolts. Still no pressure? Check for leaks, or you might have a bad caliper or master cylinder.

Happy bleeding!!!


I just flushed my system yesterday and in trying to find a syringe-type device, I came across this ketchup bottle with a nozzle that fitted perfectly with the 1/4 hose I was using. They are easy to come by, cheap, and hold all the fluid you need. The only problem I found, as opposed to the syringe, is that you have to keep pressure on the bottle while you have bleeder screw open otherwise it will suck the fluid out. But this setup also works in the reverse, for sucking the fluid OUT of the system for flushing. Also, the fit was so perfect around the nozzle that I was able to put about 15-20 psi pressure on the bottle without the hose popping off.

Side note: If you get any bubbles in the hose while your getting it onto the bleeder screw, just turn the bottle upside down above the caliper and flick the hose until the bubble floats up through it and into the bottle.

Another side note: I spent a couple years in an auto shop and the system we had there was a big container of brake fluid that we hooked up to an air compressor. It had a hose that lead to an adapter that you'd screw onto the reservoir. With pressure in the container pushing fluid into the reservoir/brake system, all you had to do was attach a hose/bottle to the bleeder screw and when you opened the screw the fluid would come shooting out. You just shut it off once all the air bubble came out. I was trying to think of a similar setup for bikes, where you modify the reservoir cover, attaching a hose and then suspend a big jug of fluid over the bike, high enough that gravity would push the fluid through.


bleeding_a_dry_brake_system_in_5_minutes.txt · Last modified: 2009/09/06 15:04 by