A Mity-Vac tool can save you time and effort when bleeding your brakes.
They are available at most auto parts stores, WalMart, and many online outlets.
If you are already familiar with bleeding brakes the conventional way, here is the quick version of the quirks of using the Mity-Vac:
The tubing that comes with the Mity-Vac will allow some air in around the bleed screw, so you need to use a tie-wrap, or insulated wire, to snug the tubing. Take care not to pull air in through the master cylinder – the Mity-Vac can draw a lot of fluid through pretty quickly, so keep refilling the master cylinder. Open the bleed screw, secure the tubing on it, and pump the Mity-Vac until no air bubbles are evident, refilling the master cylinder as needed, close the bleed screw, and onto the next caliper.
Step-by-step version:
Brake fluid is nasty stuff that will eat your paint and plastic, so take preventive measures in case you spill a little around the master cylinder. Wrap and secure a damp rag around the base of the front master cylinder.
Remove the master cylinder cover, put it someplace it won’t get dirty or wet.
The tool of choice for turning the bleed screw on the caliper is a six-point closed-end (box) wrench. If you use anything else, take care not to round off the bleed screw.
Remove the bleeder and make sure it is clear of any spooge.
Replace and loosen the bleed screw about ½ to ¾ of a turn, and put the tubing from the Mity-Vac on the bleed screw, securing it by twisting a small piece of insulated wire around it. This is to keep air bubbles from entering the tubing from outside the bleed screw and misleading you into thinking you are still getting air bubbles from the brake system.
Pump up the Mity-Vac, it will start drawing fluid through the system. Check frequently to make sure the fluid in the master cylinder reservoir doesn’t fall below half-full – you don’t want to pull more air in. After a few fillings of the master cylinder reservoir, you should be getting no more air bubbles appearing in the tubing. You want to keeping pumping fluid through until all the old fluid is out of the system and you’re drawing clean fluid with no air bubbles. If you’ve filled the Mity-Vac’s reservoir more than once and are still getting air, it might be that you didn’t really get the tubing secured around the bleed screw.
While the Mity-Vac is drawing fluid with no bubbles, close the bleed screw.
Remove the Mity-Vac tubing, empty the fluid from its reservoir.
If the lever feels anything but solid and firm when you give it a squeeze, you may need to finish the job using the conventional method.
Follow the same steps for the rear brake. It can be more troublesome as its master cylinder is not as elevated like the front one. Spillage is not as problematic, but the location can be a bit awkward, take your time.
Do this at least once a year, flushing out all the old fluid, and you’ll probably never have to clean out spooge again.
Bonus tip:
Speed bleeders make brake bleeding an easy and quick one man job. They have a one way valve and sealed threads that prevent air from being sucked into the system during the brake/clutch pedal up stroke. If you are installing Speed Bleeders (highly recommended) just completely unscrew the original bleeder nipple and screw in the speed bleeder. You will feel resistance when the thread sealer starts to screw into the caliper. Torque the speed bleeder to only 32-40 inch pounds (about 3 foot pounds). That's like having a one foot long wrench with a 3 pound weight on it (not much torque). Go easy on them. You don't need to know the size of your bleeder nipples when you order speed bleeders, just tell them the year and model of your bike, they know what fits.