Bleeding KX front brake?

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Feb 26, 2002
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#1
I was working on my 99 KX 250 last nigth and put in a new master cylinder kit and now I can't get brake pressure. The first seal had a tear on the original one but it would work then beed down after holding on to the brake for a while. I've take it back apart several times to try and figure out what is wrong but all seals point in the right direction (open cupped ends toward the brake line). I've bled a lot of front brakes but i'm stumped on this one. Do I need to have the MC honed?
 

marcusgunby

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Jan 9, 2000
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#2
Normally you need to back bleed it-by pushing fluid up into the bleed nipple on the caliper, the reason is the seals dont push air very well.Once you get soem fluid into the system the seals push out onto the sides of the bore (as designed) and make the pressure.
 
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#3
In this case you have a few options.. One is to apply a vacuum to the caliper and pull fluid through the open bleed.. Second would be to apply presure to the master end.. It's up to you, but pressure is better in my opinion.. Pressure from the bottom with fluid only is the best solution, but requires a Motion-Pro injector of somekind.. I have the V12 myself.

Jon
 
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#4
Thanks, after taking it apart no less than a half dozen times, buying the wrong size tire and realizing it after I had it mounted by a shop, and not being able to drive the rear wheel bearings out after an hour of pounding, I was about to have a nervous breakdown. Now I just need to do the fork seals :)
 
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#5
After dismounting the master cylinder and holding it striaght up over the bars, I got it beed in two strokes of the brake lever. :)