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Discussion Starter #1
Hi
I’m having trouble with the rear brake. I got some lower pegz on the 500, so adjutant the brake pedal down a bit , it worked last few rides out but today the brake doesn’t work. I’ve messed around with it to day and it will bite just a touch?, pads are ok there’s fluid in it, must be simple, what am I missing ?
Thanks


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Did you adjust the pushrod going up into the MC? Moving just the pedal throws this adjustment out. Re set it by loosening the two 10mm nuts. Allow 3-5mm play or it’ll overheat and apply the brake....
 
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Discussion Starter #3
Yeh I adjusted the pushrod up a bit when I did the lever,like I say it worked last time out but Now it just barely grads. I’ll have a good look this week, just thought I’d missed something silly!
Thanks


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Try replacing the fluid and fit new pads. I’ve found brakes can be sensitive to pad thickness. Bin at 50% material left and fit new. Never had an issue since.
 

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I've found that the rear master cylinder on my bike needs totally stripping and cleaning out every couple of years, especially if you go through deep water, once it has been stripped cleaned and put back together it works very well.
 
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Discussion Starter #6
Hi
I got home tonight, and had a good look at the brake, there are no leaks , the pads are fine, the fluid was a little bit low so I topped it up put the bike on the stand to spin the wheel then push the pedal and the brakes grab. Now I did this the other day but when I actually ride the bike the brake the brake don’t Work.when I screwed the plunger in could I have knicked the rubber boot?, or would I see fluid around the pin?





If there was a leak, surely I would see when I pumped the pedal?


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Take it apart, its easy to do on the rear MC, you can remove the piston, seals etc, give it all a good clean. If there is fluid on the dust seal then it needs some work doing to it but I would not just assume that the seal is knackered, it could just be crap stuck between the seal.

When setting up the brake the piston must be allowed to full extend when the pedal is at rest, you should be able to push the pedal a mm or two before the piston starts to move up the bore, you can check for this by watching the ball joint, there is usually enough play in that joint to spot the tiny amount of moment that you can apply to the pedal without the piston starting to move. If the piston is 'up the bore' when the pedal is at rest then it won't work properly, the brake may lock up when it gets hot.
 

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That rubber boot you have your finger on isn’t the seal. The liquid coming out might be just water. Sniff and lick test it? Muddy piss puddle water or highly toxic brake fluid?

Pads look good. If more fluid improved things maybe it was just low. My guess is it needs changing. If you still have issues do an mc seal replacement.

One thing on pads......KTM brembo, Magura or Braketec use thin amounts of pad material. It helps increase weight loss overall (thin discs and small caliper to). Trouble is it’s less life, more heat, frequent changes, not as robust.

Have a look at a bike with Nissin brakes. Much thicker pads, nearly twice the friction material and also a larger mass in the caliper (heavier). Thing is, they are top notch, more robust but slightly heavier. KTM spend a lot of money on shaving weight on all sorts of bits, sometimes it works, sometimes it’s making the product crap and customers do a runner.
 

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Discussion Starter #9
Thanks for that info lads, I hope to get the bike out this weekend and test the brake. If it’s still not wot I’ll strip it. Doesn’t look to hard on YouTube!


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