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KX100 front brake problem???

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Hello, everyone. 

I'm a new member, but have been lurking around here for years soaking up info. Thanks to all who contribute! 

I've recently acquired a '07 KX100 to turn into a woods bike to replace the '03 XR100 the wife has been slowly destroying. The problem is that while the bike has triple the power of the XR, it only has half the brakes! The little XR can lock the front tire at speed with two fingers using drum brakes the size of a beer coaster(they are slightly modded, of course, stock XR brakes suck!), but the KX barely stops with all four fingers pulling hard!. The lever is hard, so it's likely not a hydraulic problem unless the end of the MC is packed full of crud. Rear brakes feel normal and work very well.

My question is: Do these bikes just have crap front brakes? If so, what do most do for an upgrade?

I haven't taken it apart yet and suspect a problem with the caliper or pins. I just thought I would ask around and see if they might have naturally weak brakes or a known common problem that causes them to be weak until I get a chance to look at it.

I plan on the usual pipe and silencer, fww, reeds, jetting, handlebars, and handguards to mod it for woods riding as well as some restyled plastics (I've never seen such ugly fenders!), but I need the thing to stop first!  

What kind of problems or other mods should I be on the lookout for with these little 100s? Other than the front brake, the little bike is none too shabby and should make a spiffy woods bike after some tweaking.

 

Thanks in advance for any info/advice you can offer!

Dylan

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Not sure, but does the front brake line run under the fork leg?  I owned several KX 125's through the years that had this routing, and if I remember correctly it was a known culprit for a mushy front brake?  

A lot of guys were ditching the front brake assembly for a Honda setup, not sure how this translates to a mini though.

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It runs under the axle but not under the fork. The hose runs down the front of the fork and then turns just under the axle to run between the fork and rotor to the caliper.

The brake isn't mushy. The best way I can describe it is that they feel "wooden". The lever moves the distance it should and gets hard, but even with 4 fingers the brakes have very weak power.

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I'm running a crf master, SS galfer line with honda routing, and honda cr OEM pads on my 01' KX250. In my case, I believe the master bore size was too large and not generating enough pressure. I choose to run honda pads since I have heard others running them in there non honda bikes. HUGE improvement with these changes.

 

Obviously, you need to make sure your brakes bleed, no worn components, etc before swapping parts.

 

 

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Most likely contaminated pads. Did it, or does it have leaking fork seals? The first thing I would do is replace the pads and clean up the rotor, as long as you don't see a reason to bleed the system.

Edited by 351mustanger
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351mustanger wins!

I hauled the little bike to work this morning to start teardown/inspection and to take a look at those brakes. The fork seals are pouring and it's contaminated the pads. No wonder they don't work, they are well lubed! It looks like it has low hours but has been neglected pretty bad during that time. That's ok, nothing I can't fix.

Now the fun part begins...muhahahahaha  :devil:

 

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I have had plenty come in wanting forks rebuilt. Some wait way too long and the the caliper and pads are soaked. I always tell them they will need brakes too. The thing that some don't realize is, if oil is coming out of your forks, dirt is getting inside of them.

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Thanks for the links!

I have a YZ250 with the same style KYB forks so I'm very familiar with rebuilding them. I might have to make or buy a smaller seal driver, though.

I went looking for a FWW and saw where Steahly makes a kickstand for it. Awesome!

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1 minute ago, DELuth said:

Thanks for the links!

I have a YZ250 with the same style KYB forks so I'm very familiar with rebuilding them. I might have to make or buy a smaller seal driver, though.

I went looking for a FWW and saw where Steahly makes a kickstand for it. Awesome!

No problem. I use PVC tees cut in half for seal drivers. It works. 

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That's a good idea. Do you find the light weight to be an issue? The last one I made was from a car wheel bearing race. Worked perfect!

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1 hour ago, DELuth said:

That's a good idea. Do you find the light weight to be an issue? The last one I made was from a car wheel bearing race. Worked perfect!

It works OK. I use a rubber mallet so that does not make things any easier.

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