Bleeding brakes


Techie Answer Guy
Donating Member
My front brakes seem a bit spongy. I was thinking about bleeding the front, but I've never done it. I've read about the SpeedBleeders which makes it very easy as well as that Mighty Vac thing. Can I use both? I'll be doing this myself, and am looking at wasting as little fluid as possible, and minimizing the mess.

Stupid Newbie Question 1:
Assuming there's air in the lines, does it automatically seek the highest point in the line?

Stupid Newbie Question 2:
If so, how am I supposed to get it out at the bottom of the brake line if it's up by the master cylinder? Does pumping the brakes force it to the bleeder valve?

Lastly, any suggestions/recommendations about tools, techniques, etc.?

I thank you, my bike thanks you, and my wife will thank you. At least I hope she would thank you.
Bleeding brakes on a bike is not friend (mechanic) has a "vampire pump" to bleed the brakes and replace the fluid at the same time. Take it to a mechanic, or let someone else ride it and see what they think........coming off other bikes makes the Busa brakes feel spongy largely due to the weight of the Busa.
dunno the answers... But, since you are doing that... May as well replace lines with Goodridge Kevlar jonts!

Get the Mightyvac, a spool of teflon tape, an 8mm open end, DOT4 brake fluid (DOT 5 has silicates and/or stuff in it made so it does not ruin paint, but won't brake worth crap, just stick with DOT 3/4... DOT 5.2...or point something is like 4, though).

OK, remove the valve fittings one at a time (one per caliper piston set, 4 total... two per bike side). Wrap the teflon tape on the valve threads (counter-clockwise if the threads are facing away from you, valve facing towards you, clockwise if vice versa). Replace each valve and move on to the others. The teflon tape makes it so no air gets sucked through the threads, which will make determining whether the lines are clear impossible.

Go ahead and open the master cylinder reservoir. Get the mightyvac, attach a hose to the vacuum, the collector can to that hose, the second hose to the can and a needle nozzle to the end of that hose. Suck the reservoir clean (don't worry, as long as the brake is not pumped, you will not get air into the master cylnder itself). Add fresh brake fluid and suck it clean again. Add fresh brake fluid again and keep it topped.

Now, working on the left side of the bike, look at the valve on the piston set closest to the center of the bike (i.e. the point furthest from the master cylinder. Remove the nozzle from the vac hose and attach the hose to the valve. Might be a good idea to fit the wrench over the valve nut first if it is not an open-end. Just make sure you have enough travel space to open and close it.

Pump the vac a few times, 10-15 psi works well, and open the valve. It will suck. Watch the line to see how much dirt and air goes through and keep an eye on the master cylinder, do not let it go dry... that would suck.

When it comes clean, close the valve and replace the hose onto the valve next closest to the master cylinder, in this case the outside, left side (err, if I remember correctly, it's all logical once you look). Do the same as before and then move onto the inner right side, then outer right side.

To verify all the work and make sure no air is in the lines, remove the hose on the vac, remove the collector can, open it and place one end in the can and one end on the furthest valve (again, the left, inner, just as if starting over). Pump the brake lever a few times and open the valve. The fluid will move more slowly and you get the agitation from the pumping which will loosen any bubbles that may be stuck. Repeat for the other three, again same order as before.

When it looks good, top off the reservoir to the line inside (not too much, otherwise it will start spewing all over your windscreen, triple clamp and inners when you are riding). Replace the cover and pump the brakes several times. It might feel a little soft for a short while, but then get hard after a few miles. Just make sure the bike stops fairly good before testing, if it is too spongy, something is wrong (dirty discs, fluid on the pads, warped discs, bad piston seals, etc.).

Don't worry about using as little fluid as possible, either. Just get a pint or a quart, use as much as you need and trash the rest. After opening the bottle and being exposed to air, it starts absorbing moisture. However many months down the road when you bleed the lines again, you are best using a brand new bottle than one just as old as the fluid you last changed.

Easy way to get a firmer brake lever.Remove cover fom top of caliper slowly push apart the pads then slowly pump lever then repeat on other side.
Easy way to get a firmer brake lever.Remove cover fom top of caliper slowly push apart the pads then slowly pump lever then repeat on other side.
wont get rid of the old fluid thou , which if its more than a few months old will have moisture and debris in it .

 Juggler dont worry about wasting fluid...if yer gonna go to all that trouble , get all the old shid out , even if yer bike is new , fresh fluid are a good thing . Give the idea of a mechanic a shot , the vac pump that I use cost me 80 bucks.
 You can always use the tube and container trick too,if you wanna save yerself some $ (on a Mighty-Vac ). It just takes longer . You can use a turkey baster to suck the fluid outa the master .
  There's always a trick .
                                    hav a good 1.....RSD.
This is the Ol'  back yard mechanics technique  
Take a piece of clear fish tank line and insert it onto the bleeder fitting.  If it's the front brake your doing, insert to the caliper that the brake line ends to. (piggy back system on the Busa)  Put some brake fluid into a glass container.......a pickle jar works well .....and make sure the end of the  line from the bleeder fitting is below the surface of the fluid in the jar..........KEEP IT BELOW THE SURFACE

This prevents air from returning up the hose.

Open the reservoir top and have some one ready to squeeze the lever when you tell them to.  You can do it yourself but it's just easier this way.

Now......use your 8mm spanner to open the bleed fitting.  When it's open have your assistant pull the brake lever Pull should be firm and rapid.  Make sure that hose is in the fluid or it's gonna be messy. Do not release the lever but hold it to the grip until the bleed fitting is doesn't need to be TIGHT  just closed.  Release the lever.

You'll see fluid feed out of the clear hose and into your pickle catch jar.  Any air bubbles present will also be seen moving through the hose.

After two to 3 cycles of this, fill the reservoir with clean fluid..... slow, so as to keep out air bubbles from the pour

Continue with the above procedure until you see no bubbles or if ya want to replace all the fluid......until it is clean and clear.

It is important to close off the bleeder between cycles as this expedites the removal of bubbles and fluid.

If you happen to drain the reservoir and air gets into the line..........then Ya have to start all over again and it can take a fair amount of fluid to chase the bubbles out.  This is where the vacuum/bleeder is most efficient.


If a quick bleed is all you need.  This method is REAL quick and effective.

I've replaced brake lines using this system in the past..........usually when visiting a friend and there's no access to my tools

PM me if ya have any Q's