[marius_]

@marius_ Seems unlikely the top nut of the exhaust valve might be causing the noise…

Checked today for peace of mind, yes it's all alright down there. But the nut I found is weird, perhaps it's not from my bike at all


sorry for editing once more, just be sure to read the post prior to this one on page 1 which has the new findings of today

 

[Grossi.BP]

Ah, could be that some debris acts as sort of a 'trumpet' with the air flowing around. Don't give up! : )

 

[marius_]

Air filter is clean... might be the water cooling system... The noise appears when the engine is warmed up. I just need to pull the throttle in neutral on the parking lot. Any other ideas what I could check before going to the dealer on Thursday?

 

[Grossi.BP]

I think you could just get rid of the fairings - once it saves time at the dealer - later you can put them on "for free", second you are not limited with them to hear and use the "spoon" or screw stetoscope? It's still couple of days till Thursday... Airbox... but if it would get unwanted air for example the engine would not work smooth, you know, the mixuture is not ideal to be burn - I doubt computer can correct it. This "trumpet" 🎺 sound is not fitting to a big thing... it's too high. Could it be some of this hoses for pressure in the tank or hm... ok, clearly I'm out of ideas now.

 

[marius_]

cooling liquid seems alright in terms of quantity. water pump pressure blowing off? it sounds like some overpressure valve that blows, but the noise appears "all the time" which then would be weird can't be constantly blowing off something for the last 700 km.

 

[marius_]

Ducati wrote back on Whatsapp, say they need to have a look at it. No hint as to what else I could check, though.

 

[marius_]

edit: the below didn’t fix it. Read on in post #30.

Ducati listened to the noise this morning and said it's the timing belts, which have too much tension. So when hot, they make this noise. It's unusual they said, for the age of my bike and the km it has been ridden. Anyway they gave me a Diavel 1260 as replacement for today because for the correct tensioning the engine needs to be cool, obviously. I'll pick it up tonight and hope it's solved.

 

[marius_]

I bought the bike at a KTM dealer, perhaps they put too much tension on them during inspection before selling it...

 

[Ed K]

@marius_ Wow, very interesting…

 

[marius_]

I picked up the bike but the noise is still there. They adjusted the timing belts but it wasn’t the root cause. Something is weird in the airbox, there are apparently some flap/oneway valves and hoses which can cause the issue. Ducati will need 5 hrs to take it all apart and investigate. Since my bike has seen the service regularly, Ducati may share the labour cost with me 50:50. It’s out of warranty so it depends a bit. If they find something really wrong then they may also pay it all.

At least it’s nothing crucial and I could choose to leave it as is, technically. But I can tell you that’s no option as the noise is very annoying for me. I may open the airbox myself once more or think about making the 5 hr appointment, earliest August 20.

 

[brucemswan]

FWIW, my bike made a similar noise but under different circumstances. The sound was very similar to yours, but a constant high pitched sound. I noticed it when I turned off my bike after a ride. It turned out to the one of the vent hoses for the gas tank that apparently had been compressed when I was reseated my tank after doing some work. I'm not sure which one it was, I just lifted the tank again and made sure the hoses were cleanly sorted and there was no gathering under he tank and the sound went away. Believe someone else on the forum had a similar problem. Probably not the same as you but easy to check out.

 

[marius_]

FWIW, my bike made a similar noise but under different circumstances. The sound was very similar to yours, but a constant high pitched sound. I noticed it when I turned off my bike after a ride. It turned out to the one of the vent hoses for the gas tank that apparently had been compressed when I was reseated my tank after doing some work. I'm not sure which one it was, I just lifted the tank again and made sure the hoses were cleanly sorted and there was no gathering under he tank and the sound went away. Believe someone else on the forum had a similar problem. Probably not the same as you but easy to check out.

Yes, I'll lift/remove the fuel tank and check myself what's up. In the spare parts catalogue drawings I haven't found any rubber flapper valves Ducati mentioned, but there are some ventilation hoses and valves (crankcase ventilation, fuel tank ventilation etc.). I might have to remove the tank, so I'll be looking for instructions if available. The new air filter arrived, and I'll exchange it as well in the process anyway, so it's a win-win to open up the fairings again and all that

I hope I'll be able to leave the fuel lines connected so I could run the engine with the tank lifted up. Then I could touch all hoses and see if one of them causes the noise.

 

[marius_]

I had it all opened up today but I can’t really find the root cause. It’s not louder when the airbox is open. I’m still thinking it might be some bearing somewhere in the front of the bike. I guess I’ll have to get it back to Ducati and let them take it all apart.

 

[Ed K]

@marius_ Hoping not, but it seems to be leaning in that direction... Only thing though, if is a bearing, one would expect it to progressively get worse, and it doesn’t seem to be getting worse(?).

Can you run the bike with the fairings off and see if the noise continues? I recall a time when a strange squeaking noise was occurring for a Member's bike a few years ago, that we couldn’t figure out. And it turned out to be a plastic part rubbing against another part at certain resonant frequency! We were all pleasantly surprised, as we were thinking it could have been something much worse.

 

[Ed K]

As a recall, those plastic parts resonating on the other Member’s bike turned out to be parts of the license plate assembly resonating! A long shot with yours, but you might check that out, too…

 

[marius_]

Thanks @Ed K, yes I had the engine running with the fuel tank sitting vertically on the rear pivot and air filter out. No change, it’s still somewhere in the steering head area. Not really in the airbox I think. I made photos of the airbox inside and it looks all ok to me. Not much in there anyway.

All it takes to generate the noise is letting the engine warm until hot (I let it run until the fans started spinning) and pull the throttle short, even slightly. You can hear it put-put-put…

Nevertheless the noise is still the loudest when rolling with clutch engaged and without throttle. Then it’s continuous at mid-high RPM and sputters slowly at low RPMs.

 

[marius_]

For what it's worth, I ordered a mechanics' stethoscope for 10 bucks to arrive on Monday. I can't accept the noise is somewhere and not to be found

 

[marius_]

I did my search and I haven't found the noise. I think it's not from the airbox but somewhere else. Then again, no part is mechanically transmitting the noise to the stethoscope. I think it's some air whistling in some pipe which isn't easy to find with this method. Or it's a bearing where I can't get to reasonably... In the end my rear tire was smoking from all the heat rev'ing the engine while not moving at all. I'm wondering if that's a potential issue in a traffic jam if you don't move at all...

Funny enough, I did a short ride with a passenger afterwards and the noise was much less... Perhaps because I was going much slower than usual; or the heavier weight changed things for the better... I think I'll have Ducati check; they'd also find unusual things which I wouldn't see.

 

[Ed K]

Yes, rear tire will heat up from CAT just sitting, when not even running.

Have you checked to ensure the noise isn’t from plastic parts resonating through certain rev ranges to produce those noises? Check unusual spots too, like license plate.

 

[marius_]

Yes I sampled the whole area, also clutch etc. although the sound clearly is somewhere in the front.

I'd say it's on the front behind the watercooler. Today I stopped during a tour and went around the bike, touching whatever I could touch, like water cooler, plastic covers etc. No success yet. My next move would be to check the spare parts catalogue (I'm like reading it almost daily for something these days ) and see which lines run behind the water cooler assembly.

The thing bothering me most right now is that the noise stops when I push the throttle even slightly. It seems to be tied to whether there is load on the drivetrain/gears/etc. Could it be in the water system? Like, pressure changes when accelerating compared to letting it roll? I'm thinking the water pump gears are connected to the engine in a rigid way, meaning that the water pump RPM would not change when a) riding at x km/h with throttle compared to b) riding at the same speed with clutch engaged. Still the noise disappears when I turn the throttle even slightly and it disappears mostly (but not entirely) when I pull the clutch and let the engine settle at low RPM.

Could it be one of the injectors? Those would stop injecting I guess, when rolling without throttle, because the engine is being turned by the rear wheel and chain inertia. And at low RPM they wouldn't have to work much. I can reproduce the noise while standing and just rev'ing in neutral.