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Thread: 2017 fx 450 mushy front brake

  1. #1
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    Default 2017 fx 450 mushy front brake

    try to help my son diagnose a way mushy front brake , so far we rebuilt master cylinder, installed over size rotor, bled a million times ,still no good , Compared to an older ktm these brakes suck, Too much lever travel before engagement,Could it be the the after market lever that came with bike. Not sure of brand, is there an inherent problem with these brakes.

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    Default Re: 2017 fx 450 mushy front brake

    I way overheated the front brake on mine one time. Bled it a few times and changed pads, but it's never been quite the same since. Figured I glazed the rotor and just doesn't bite the same anymore. If you changed the rotor that shouldn't be an issue. Brake lines can go bad. Had it happen on a race quad. they were even Galfer braided lines. For some reason the lining inside split or started coming apart. Couldn't get pressure and the fluid kept coming out dirty and contaminated. Changed lines and all was well again.

    I've also read on here where guys seem to get a bad master cylinder from Brembo and rebuilding it doesn't help. Must be a poor casting job? Replacing it with a Nissin is a fix if you don't want to gamble on another Brembo.
    Last edited by quad97; 10-16-2020 at 04:29 PM.
    2017 FX450
    2009 505SX Quad
    2008 525XC Quad, modded for MX
    2008 450SX-F Bike - Sold
    2004 Arctic Cat DVX Quad
    1987 Honda 250X Quad- Sold

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    KTMTalk Member dirtbikeace's Avatar
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    Default Re: 2017 fx 450 mushy front brake

    Are you backbleeding up from the caliper otherwise you are wasting you're time. Do you have a Brembo master cylinder they lose pressure overnight and usually by spreading the pads restore a firm lever, as mentioned if it happens every day for almost a year I replaced mine with a Nissin. The brembo has been a problem for 20 years but when it works right it will put you on your head which some like, the Nissin is much more forgiving and easier to use.
    present bikes
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    1999 Kawasaki Concours
    1983 Husqvarna 250WR
    1968 Honda CT90 trail 90
    1971 Suzuki RV90
    1964 Honda CT200 Trail 90
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    KTMTalk Member KXcam22's Avatar
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    Default Re: 2017 fx 450 mushy front brake

    A trick is to keep the brake lever in with a rubber band when bike is sitting. Theory i was told is that it lets micro bubbles out. It does work to improve feel. On my bike ktm i put a ballbearing in the lever cup to push the actuator in further. Makes level feel excellent but wont know until end of ride tomorrow if it works. What i want is a trigger finger brake with short travel. Cam

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    Default Re: 2017 fx 450 mushy front brake

    done all the tricks back bleeding, rubber band on lever over night, those tricks always worked on my 06 400 and 07 xc250, but not on this husky, must be a bad master , or brake line, ball bearing trick might work but be carefull i did something similar on my 400 and went to far so the brake had a slight drag on it and overheated and seized during a hare scramble, went down hard .

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    Default Re: 2017 fx 450 mushy front brake

    Assuming you.ve done a back bleed and the pushed the piston all the way back in. It should be bled well.

    So take a Greased zinc coated bb from a BB gun, and put it inside the lever , where its cone shaped and the plunger enters, it fits perfect and will pull all adjustments to nominal, should have about .1mm free play before touching the plunger, all set after that.

    Ive run this set up for going on 6 years, works great


    This is for a master that is bled well , but maxed out on adjustments and engagement is still not out far enough.
    Last edited by spud786; 10-17-2020 at 08:36 AM.

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    KTMTalk Member KXcam22's Avatar
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    Default Re: 2017 fx 450 mushy front brake

    Ball bearing was very successful. 1 finger brake with about 3/4" travel and good progression. Only issue could be that the bearing makes the master cyl plunger off center. May create wear down the road. I may try building a new cup out of epoxy putty. But i see spud has had good luck with this as well. Cam
    Last edited by KXcam22; 10-17-2020 at 10:10 PM.

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    Default Re: 2017 fx 450 mushy front brake

    Quote Originally Posted by KXcam22 View Post
    Ball bearing was very successful. 1 finger brake with about 3/4" travel and good progression. Only issue could be that the bearing makes the master cyl plunger off center. May create wear down the road. I may try building a new cup out of epoxy putty. But i see spud has had good luck with this as well. Cam
    I understand the theory, and why to use water proof grease, but ive not seen any detriment in my near 6 years 54,000 miles. not really noticed any obvious wear issue to be addressed.

    The only thing is to ensure, there is still play between the plunger actuation and lever, so the plunger does return out to its full stop.
    Last edited by spud786; 10-18-2020 at 07:18 AM.

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    KTMTalk Member utemachine's Avatar
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    Default Re: 2017 fx 450 mushy front brake

    Ive got this same problem with the Brembo and tried everything including burning incense to exercise the demons. What Nissin are you all referring to? Is there a part number?

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    Default Re: 2017 fx 450 mushy front brake

    Quote Originally Posted by utemachine View Post
    Ive got this same problem with the Brembo and tried everything including burning incense to exercise the demons. What Nissin are you all referring to? Is there a part number?
    I used one off a DRZ 400, most like honda's. The brembo and Nissin use a different thread pattern so get the banjo bolt that goes with it.
    present bikes
    2006 KTM 450 EXC
    2006 KTM 400 EXC
    1999 Kawasaki Concours
    1983 Husqvarna 250WR
    1968 Honda CT90 trail 90
    1971 Suzuki RV90
    1964 Honda CT200 Trail 90
    member Great Lakes dual sporters
    www.gldsmc.org
    AMA charter life member-663466A

    District 14 ama- #0025

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