Lost rear break pressure on ktm 525 exc

Discussion in 'Thumpers' started by Ivanvm, Sep 17, 2012.

  1. Ivanvm

    Ivanvm Adventurer

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    I took out my dirt bike out after a long summer break. As I started going down the hill I noticed I had no rear break. The break is there but pressing on the plunger causes no pressure on pads. Inspected the fluid level and it's fine. Lines are free of obstructions and undamaged. I am no mechanic but I can usually find my way around my bike but this one has me puzzled. Any ideas why the pressure is gone?
    #1
  2. Marco Moto

    Marco Moto Voyager

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    If the pedal is hard to push then your caliper piston is stuck, if the lever goes down with no pressure then your master cylinder needs to be rebuilt. Rebuild kits are available online for +- $30, good luck!
    #2
  3. tutone

    tutone Adventurer

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    My 530 did the same thing last weekend and now in the shop for a Master cylinder rebuild. Actually I was told debris plugs some small venting hole. I trust my mechanic and he said this is common on KTMs
    #3
  4. Ivanvm

    Ivanvm Adventurer

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    Thanks. Must be the master cylinder. Will get the kit.
    #4
  5. dbarale

    dbarale Squiddly slow

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    Have you tried bleeding it first?
    #5
  6. sailah

    sailah Lampin' it

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    +1

    Thats the first thing especially if it was working fine you probably just boiled the fluid, there isn't much in those master cylinders
    #6
  7. Ivanvm

    Ivanvm Adventurer

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    Makes sense. Will get a pump and bleed the lines. Will report back in a couple of weeks (off to Cancun for 7 days). :) Rubbing it in... :evil
    #7
  8. Jacl-Kampuchea

    Jacl-Kampuchea Booze Merchant

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    Happens me on my 450 all the time. I have to be careful not to be slightly weighing the lever with my boot or I boil the fluid and notice I have lost the rear at 70mph in sand:eek1

    When it happens it cools down in 5 minutes and I can pump the pedal to bring pressure back up.
    #8
  9. Ivanvm

    Ivanvm Adventurer

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    Finally I got a chance to bleed the break and it did the trick. The rear break now has pressure and seems to be working properly. I will try it tomorrow to see if it is working properly. Thanks for all your advice
    #9
  10. elsalvadorklr

    elsalvadorklr southern xr rider

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    your just boiling it so bleeding/flushing every once in a while helps...and not riding the brake too...
    #10