Re: KTM Duke 390 - Ownership Reviews and Experiences

He has replaced major kit also.

Re: KTM Duke 390 - Ownership Reviews and Experiences

Sometimes cleaning brake pads thoroughly also helps
My bikes brake felt spongy when SVC guy cleaned the brake pad thoroughly with brake cleaner.. they are now as good as new.


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Re: KTM Duke 390 - Ownership Reviews and Experiences

I am suspecting a pressure loss due to faulty brake line, albeit extremely minimal enough cause this sponginess. Usually, a faulty banjo bolt, the bolt that secures the line to the caliper, if this bolt is faulty, you will loose pressure and so are the bleed bolt. Also, if the bleed bolt is not helping the caliper hold pressure, then you will spongy brakes irrespective of the piston seals or piston replacement. I'd suggest you get a brand new caliper with piston now that you've tried all of this. Absolute brand new components, including the banjo bolt and the washers that go along. This is a summation I can speculate for now from your experiences, it could again be something else.

Also make sure your front rotor thickness is in check. A worn out rotor would mean excessive pad/piston travel, which would mean spongy feel. How good is your front rotor?

Cheers!
VJ

Re: KTM Duke 390 - Ownership Reviews and Experiences

Was brake fluid reused during all this caliper rebuild saga?

Try changing the brake fluid completely from a fresh just opened bottle and see if the spongy feel disappears.

Also check for leaks in the braking lines so as to narrow down if air is being pulled into the system giving a spongy feel at the lever.

To me, if the brakes feel spongy, then it should definitely be air in the system. I may be wrong too.

Re: KTM Duke 390 - Ownership Reviews and Experiences

I asked him to check the lines and he said no leaks. I"ll get the caliper replaced and try my luck.

Re: KTM Duke 390 - Ownership Reviews and Experiences


Hi Nitin,

I had the exact spongy feeling at the lever on my MY17 390 and did a complete brake bleed at home.
Note: Mekhri Circle has one of the worst set ups as well as mechs, avoid!)


I suggest you bleed the entire system once. Then take the bike out and engage ABS a few times to purge the ABS pump of air. Then go back and bleed the system once again.

This fixed my lever feel and now its back to how it should be.

Re: KTM Duke 390 - Ownership Reviews and Experiences

Most ABS modulators are more or less self bleeding, meaning they bleed as you bleed your calipers and master cylinders as normal, unless some high tech bikes where you have a separate ABS modulator bleeder screw. What you can do finally, is remove your ABS lines, drain out all the fluid and then re-bleed the entire system using good quality, brand new DOT 4 brake fluid.

The key here is to drain all the brake fluid out of the ABS Modulator. Yes, this requires removing the lines from the modulator itself, but it's easily doable and then reinstall everything back with fresh new fluid. That's all I can think of right now, apart from the answer I've posted a few posts earlier.

Keep your observations jotted.

Cheers!
VJ

Re: KTM Duke 390 - Ownership Reviews and Experiences

Typing from mobile so dont know how to multiquote.

Both the replies above confirms what I suspected-that caliper replacement is not necessary. Though brake has been bled three times, caliper was not overhauled. Now that caliper is overhauled, brake fluid replacement (though this was also done less than 500kms ago) and proper bleeding should do the trick. Will get it done next weekend keep you guys posted.

Thanks once again for the replies.

Re: KTM Duke 390 - Ownership Reviews and Experiences


Sorry, missed out on this post. Your diagnosis matches with Service Advisor's observations. His observations are: -

1. Bleed nut was stuck and it had to be removed in lathe shop
2. There is a 'step' (uneven wear) on the inside of the rotor. He said this might be due to pad rubbing constantly to the disc.

I think system not able to hold pressure, air leak is the cause for this. I'll will get the bleeding done once more with fresh brake fluid. If it doesn't fix the issue then new caliper it is.

Re: KTM Duke 390 - Ownership Reviews and Experiences

please mention price and where did you buy this ??

Re: KTM Duke 390 - Ownership Reviews and Experiences

my seat is very uncomfortable, should I add more cushion or air suspension seat ??

Re: KTM Duke 390 - Ownership Reviews and Experiences

Since 4-6 weeks, the coolant is reducing drastically. I have topped up nearly 250-300ml of coolant in last 1K Kms. The bike fell from standstill once, breaking the gear leaver. But did not notice any damage to radiator or coolant pipes. However, looks like coolant reducing started after this incident.

Peeking into the glass window does not show any bubbles or does not seem to have increased the oil level as well. So I don't think it is mixing with oil. I'm using Motul Motocool and as it's not green cored, it's difficult to trace any leakage as well. Any other way to check where the issue is?

Re: KTM Duke 390 - Ownership Reviews and Experiences

All the Duke's seat are hard, barring the newer ones which have a better material to it

Since the Duke's cooling system is exposed well, it's easier to trace any leaks if they were to materialize. I'd suggest you start off with the radiator drain bolt itself, the small copper washer that's there, leaks very rarely happen from here, unless they are not torqued well, but just in case, if they're loose they do. Secondly, the radiator bleed bolt to the left, if that's loose, yes coolant will overflow due to the positive pressure inside the system, make sure this bolt is torqued. Thirdly, due to the temperature itself, it can be that the coolant itself vaporizes. Switching to a better quality coolant can perhaps help, Engine Ice with its blue colored or you can use Honda Radiator Liquid, best stuff.

Now to the coolant mixing part. Coolant can sometime mix due to water pump seal failure or due to an internal failure, i.e. insufficient gasket between the crankcase and clutch case, which is the case with newer lots. I'd suggest keep a tab on this closely for a few days, if it still consumes, I'd suggest you to bleed the radiator once again and use premixed Inugel, for the time being to see if they get consumed again. if yes, then we have problem.

Keep your observations posted.

Cheers!
VJ

Re: KTM Duke 390 - Ownership Reviews and Experiences

you definitely have a leak or mixing/seal/head gasket failure issue. no way will it require 250-300 under normal use in 1k km interval.
it's only if you have drained and replaced the coolant, then maybe it will need a top up once or twice in the first few days/kms.. but after that in a properly working cooling system the loss over 1k km will be negligible. so did you recently drain/refill the coolant ?

Re: KTM Duke 390 - Ownership Reviews and Experiences

I feel that ride by wire throttle on my bike is tight at lower speed. It gets better once I am at 90-100 kmph. Is this a normal thing or do I need to make an adjustment to it. Could this be an issue related to chain sprocket as I am nearing its end of life and will be doing a replacement post monsoon