790 front brake lever travel varies

IanC

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I've got a thing with my R where the front brake lever seems to get 'pumped up'. But not after hard braking, repeated use or anything, it's just the travel to the bite point reduces significantly at times, and then goes back to normal.

I'm wondering if there's an issue with the ABS pump.

Anyone else experienced similar?

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To the best of my knowledge there is no pump on the abs. Bike abs systems haven't had servo assist for several years.
 
IanC said:
I've got a thing with my R where the front brake lever seems to get 'pumped up'. But not after hard braking, repeated use or anything, it's just the travel to the bite point reduces significantly at times, and then goes back to normal.

I'm wondering if there's an issue with the ABS pump.

Anyone else experienced similar?

Sent from my SM-G935F using Tapatalk
Click to expand...

I have not experienced this on mine.
 
Marki_GSA said:
To the best of my knowledge there is no pump on the abs. Bike abs systems haven't had servo assist for several years.
Click to expand...
Maybe I was using the wrong terminology. I had two of the early GS's with the servo - dreadful idea!

But I mean whatever ABS device it is that can control the brake fluid pressure.

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Have you done a full system bleed to take any air being in the system out of the equation? Assuming no air I would say the master cylinder or even a caliper is more likely to be the cause. I take it there is no pulsing like a warped disk? It sounds like a pad is getting knocked back too far for some reason or a seal isn't being consistent. Either way given the age of the bike, the dealer needs to take a look.
 
IanC said:
Anyone else experienced similar?

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Click to expand...

YES. But by the next ride all seems well. Imagine there’s some air in there somewhere but it doesn’t exactly present as a typical air issue in my view.
 
Apex said:
YES. But by the next ride all seems well. Imagine there’s some air in there somewhere but it doesn’t exactly present as a typical air issue in my view.
Click to expand...
Currently waiting for dealer to call me back.

Mine doesn't need me to stop before it changes, it seems to vary on the fly.

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Mines the same. I just mean that if left overnight in the garage it feels perfect again in the morning.


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IanC said:
Currently waiting for dealer to call me back.

Mine doesn't need me to stop before it changes, it seems to vary on the fly.

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Click to expand...

did you get this sorted Ian?

Mine was awful last ride out. Booked in with AMS to take a look. Seems it's when the bikes brakes are used a lot. I bled the front calipers. Brake lever travel reduces to 1cm completely off to fully on! Any ideas?
 
Apex said:
did you get this sorted Ian?

Mine was awful last ride out. Booked in with AMS to take a look. Seems it's when the bikes brakes are used a lot. I bled the front calipers. Brake lever travel reduces to 1cm completely off to fully on! Any ideas?
Click to expand...
Not yet. Do you find it's only with off-road ABS?

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I think it’s temperature related somehow. So when you’re road riding the brakes stay relatively cool at speed. But off road with some steep hills mine just go off. There is some free-play of course, that’s necessary. But what happens is that free play extends more and more Until there is only around 1 cm of brake lever travel. That’s fine, but it makes the brakes very on/off Which is exactly what you don’t want when you are off-road.


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My 790 is in the dealers for this. Although you can bleed the brakes yourself it needs the diagnostic kit plugged in to open the ABS lines to do it properly. So it may yet just be air in the system.
 
So, bike back. To be honest the lever feels the same. So at some point I'll test it out and report back.


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Any further info?

I've just returned from Spain, and the problem seems to be getting worse. On five separate occasions the front brake has actually been binding and I've needed to stop. Not locking up thankfully, but I could feel it was slightly applied.

And on other occasions I've been able to pull the lever back to the twist grip. Again, thankfully, it's never got to the stage of no brakes, but I do wonder if that could occur. Riding on dirt in this situation it's flapping around all over the shop.

On road and off, doesn't seem related to heat or how much/hard I've been braking.

It's disconcerting not knowing how far you'll need to pull it, never mind the extremes which thankfully I've not yet encountered.

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IanC said:
Any further info?

I've just returned from Spain, and the problem seems to be getting worse. On five separate occasions the front brake has actually been binding and I've needed to stop. Not locking up thankfully, but I could feel it was slightly applied.

And on other occasions I've been able to pull the lever back to the twist grip. Again, thankfully, it's never got to the stage of no brakes, but I do wonder if that could occur. Riding on dirt in this situation it's flapping around all over the shop.

On road and off, doesn't seem related to heat or how much/hard I've been braking.

It's disconcerting not knowing how far you'll need to pull it, never mind the extremes which thankfully I've not yet encountered.

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Click to expand...

Went for a road ride yesterday. No off-road as shoulder still recovering. Still feel this is an impressive package on road. The brakes were bled properly at the dealers and the lever felt fine. Will know for sure when I go off road. Rear brake was binding a bit by the time I got home though!


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Finally got to my dealer (JD Racing) yesterday for him to look. After speaking to KTM beforehand, they were going to power flush/bleed the brake lines through the ABS pump, thinking there was some debris in one of the ABS pump valves. He'd even bought in a very expensive-looking KTM pressure vessel device for the job, looked like a diver's helmet!!

But when I was there, and after chatting to me, they concluded it was more likely the front brake master cylinder sticking, which made sense. So fitted a new one under warranty, after getting KTM approval. They had one in stock fortunately.

Fingers crossed, we'll see if it's sorted! I'll optimistic.

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IanC said:
Finally got to my dealer (JD Racing) yesterday for him to look. After speaking to KTM beforehand, they were going to power flush/bleed the brake lines through the ABS pump, thinking there was some debris in one of the ABS pump valves. He'd even bought in a very expensive-looking KTM pressure vessel device for the job, looked like a diver's helmet!!

But when I was there, and after chatting to me, they concluded it was more likely the front brake master cylinder sticking, which made sense. So fitted a new one under warranty, after getting KTM approval. They had one in stock fortunately.

Fingers crossed, we'll see if it's sorted! I'll optimistic.

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Click to expand...

Let me know Ian. My shoulder injuries are taking weeks to fix sadly and can’t afford another off-road drop n land on shoulder incident just now.

My lever was mostly bad offroad. Road riding not so bad.
 
Apex said:
Let me know Ian. My shoulder injuries are taking weeks to fix sadly and can’t afford another off-road drop n land on shoulder incident just now.

My lever was mostly bad offroad. Road riding not so bad.
Click to expand...
So far, so good. But only been about 150 miles.

Will report back if not sorted.

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