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Front Wheel Pulsing

My 2c

Pulsing is not the master cylinder, lines, bleeding or the calipers.
A hydraulic system does not induce pulsing on its own. It is fairly dumb, there is either no pressure, some pressure, or a lot of pressure, it does not induce varying pressure and feedback to the pump mechanism (master cylinder)

An ABS pump can induce pulsing into the hydraulic system, but that is a whole separate issue.

The pulsing you are feeling is mechanical variation either causing 1) vibration of the entire bike 2) pulsing into pump ( the master cylinder lever) or 3) both of the above.

Why? Couple of ideas
Run out or friction issues

Run out - Something is out of flatness spec causing excessive run out of the rotor at the braking surface causing the calipers to send pulsing feedback as they try to squeeze something that is essentially wiggling instead of running straight and flat.
There are really only two things that affect this, the mounting surface of the rotor on the rim, or the rotor itself.

Friction - there is some variance of the friction surface that is altering the friction coefficient as the circumference of the rotor sweeps through the pad contact breaking area leading to more - less - More - less, etc friction causing a pulsing/vibrating feeling.

New rotors, if they were the problem, would fix both of these.
New rotors temporarily fixing this shows that the rotors were partially at fault, but the underlying condition caused them to fail as well.

Why?
- defective quality rotors?
This is why a lot of owners replaced the rotors with aftermarket pads and rotors.
- slightly out of tolerance rim rotor mounting surface? Possible

I highly doubt it is anything to do with the remainder of the hydraulic system. This is a mechanical issue.
 
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Sadly it looks like there were two recalls on this bike filed with the NHTSA, and 12 complaints, many about front brake pulsing. At this point the bike is out of warranty but I wonder if there is a way I can pressure KTM into replacing aspects of the front brake system to relieve this safety issue? Does anyone have experience with KTM US?
 
A recall stands valid regardless of where you are in your warranty, they are separate things.

I don't have specific experience with KTM corporate, but I have read a lot about how they are handling the cam issues and it is really hit or miss depending on how hard your dealership representatives are willing to push the issue for you.
 
I don't know if I mentioned it in this thread or elsewhere with somebody talking about pulsing brakes, but ....
my old Ducati st3s had pulsing brembo brakes and the fix was to grind off the buttons between the rotor and the carrier and put in aftermarket ones that allowed more float of the rotor relative to the carrier.
Some people found it unnerving that there is a little ching ching sound from the rotor moving on the carrier so much, but the brakes were fantastic after that.
It just allowed more lateral movement, not radial, so there was no slop in the braking feel.

I haven't seen that discussed as a fix for the ktm specifically but I haven't spent a lot of time looking, but the principal holds the same.
 
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