How to bleed front brake line

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NWCOKDX
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How to bleed front brake line

Post by NWCOKDX »

I am so close to getting my 97 KX250 front end conversion complete but I am unable to bleed my front brake line. I have a new front brake cable using the KDX resevior but I am unable to get the brake fluid into the new brake line and into the front brake. If anyone has any suggestions I would really appreciate them.
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Indawoods
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Post by Indawoods »

MITY-VAC!
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NWCOKDX
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Post by NWCOKDX »

MITY-VAC??? I am laughing right now because I have accomplished to soak myself in brake fluid, but still haven't had any luck. Can you elaborate on the MITY-VAC???
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Post by Indawoods »

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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:

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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.
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Post by Jeb »

If you're in a hurry and a Mighty Vac is unavailable here's a way to get you riding. Find a large plastic syringe (Home depot or Walmart I believe) and a short piece of tubing (clear is best so you can see air bubbles).

Fill the syringe with fresh brake fluid. While a friend is watching the reservoir (with the top off), attach the syringe/tubing to the bleed screw, open up the bleed and push fluid UP through the brake line into the caliper until it's full. Then have your friend pump the brakes until the reservoir is about 1/4 full (don't get the level too low or you'll introduce air back into the "system"). Repeat the sequence a couple of times. You'll hear/see bubbles in the reservoir, and then you'll see/feel your friend pumping the brakes in the syringe plunger.

Go a few more rounds but on these occasions when it's your friend's turn to pump the brakes have him hold the lever in, close the bleed screw, release the lever, open the bleed screw, squeeze the lever, on and on. Every once in a while close the bleed screw and have your friend press the lever to see if it's firming up.

This will work well even with a completely dry system; gravity helps in getting air up and out of the caliper and line. Probably not as good as a Might Vac but it'll get the vast majority of the air out and you can ride until you get that Mighty Vac.

Tell us how it goes.
Last edited by Jeb on 09:14 pm Apr 10 2008, edited 1 time in total.
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Post by Jeb »

Speed bleeders - cool!! Where do you get 'em?
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Post by Colorado Mike »

You can get big syringes at a tack store.


uh, for city folk, that's a horse supply place. or a feed store. I say livestock son, not a little nail store.
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Post by Jeb »

>|<>QBB<
Colorado Mike wrote:You can get big syringes at a tack store.


uh, for city folk, that's a horse supply place. or a feed store. I say livestock son, not a little nail store.


Come to think of it, I DID get the syringes at a feed store.
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Indawoods
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Post by Indawoods »

>|<>QBB<
Jeb wrote:Speed bleeders - cool!! Where do you get 'em?

http://www.dirtwerkz.com/Merchant2/merc ... SB7100S-SS
*** Administrator //***
****'95 KDX 200/****

"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
NWCOKDX
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Post by NWCOKDX »

Thanks for all the advice, I will have to do some looking around tomorrow. Speed bleeders may be hard to find in here in town. Thanks for the link, they are less expensive than I thought they will be. I will let ya'll know how it goes.
:rolleyes:
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Post by NWCOKDX »

Inda,
Thanks again for the info, I don't know where I could have gotten better info. I didn't know such a device existed, hopefully I can find one and give a ride report on Monday.

Thanks again!!!
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