After having my 2015 model year Duke 390 serve me falwlessly for ~26,000 km, I'm starting to face my first set of issues. The first one was a broken water pump seal that showed up at around 24,000 Kms but that was dealt with under warranty. Then came a screweup timing chain, which I got fixed at roughly 25,800 kms. All these where easy to diagnose and I had a rough idea as to what is going on.
Now I'm facing something I simply cannot understand. I'd like feed back from the guys here before I take it to the SVC. The real issue is that when the engine is hot, the bike cranks fine but as the engine starts, it idles at around 900 rpm for about a second and then slowly goes up to the usual idle in the next few seconds. Been happening for about 2 weeks now. Yesterday, on the way back from a ride, I also noticed that the idle is erratic when the bike is hot. The bike stalled under a condition it shouldn't have, but maybe that was me adjusting to a new pair of gloves. I also get low battery errors from time to time that go away after a minute of idling.
Is it possible that the alternator is faulty? The spark plugs are new, got them changed when I got the timing chain changed. The stepper motor seems to be fine as the bike starts fine, idles fine and all under normal riding. It's only when the bike has been ridden for a while and gets really hot that it starts doing this. I'd really appreciate some suggestions here.

Try to get the wheel balanced. I faced the same around 140 and got the wheels balanced. After that it was stable even at 165! Before that, just check if the rim is not bent and the air pressure is alright.

Hey, may I request for your feedback post throttle body cleaning? Did you notice any improvements in throttle response?

Also, where did you get it done and how much did it cost you?

Been thinking about getting it done on my 24,500kms run 2013 D390. I am not facing any problem though.

Hey, may I request for your feedback post throttle body cleaning? Did you notice any improvements in throttle response?

Also, where did you get it done and how much did it cost you?

Been thinking about getting it done on my 24,500kms run 2013 D390. I am not facing any problem though.

In my RC 390, when I turn on the ignition I don't hear the fuel pump sound some times. I'm observing this for the past 2weeks, at least 3 4 times. I haven't noticed this before. Is this normal?

first please get the electricals checked.. i.e. the battery and stator. A bad stator will eventually damage the battery. The RR (regulator-rectifier) usually doesn't fail this early.
then also connect the diag tool and see if there are any error codes, if there are any error codes fix it accordingly, if there aren't any, do this:
1. ask them to clear the dtc (you will see this option in the diag tool).
2. after clearing the dtc, start the bike and let it idle for 15 minutes - do NOT touch the throttle
3. Shut it off after 15 min.
4. Start it after a couple of minutes and go for a test ride and see if it still behaves erratically.
* if you try to ride the bike immediately after clearing the dtc, it will idle erratically, shut down (will require you to slip the clutch and give more throttle).. this will happen for a few minutes.. so just let it idle for 15 min and let the ecu relearn.

If it still does behave erratically, then it might require a Throttle body cleaning and maybe a replacement of the idle control stepper motor or the throttle position sensor (tps). Don't fall for the "saar, we have to change the throttle body"

I'd recommend you checking your inline fuel filter, and when was it last replaced. If the fuel filter hasn't been replaced for quite a while, now is the time to consider replacing one. If it's a stock battery, I'd strongly recommend you to check the voltage at the terminals and see if it's according to spec anything between 1.5 to 15 at 5000 RPM should be a good reading; replace battery if necessary. Battery like tires and chain sprocket are consumables and deteriorate accordingly, so do have a check on them.

Thirdly and lastly, recommend cleaning your throttle body as it helps clear the carbon deposited inside which reduces the efficiency at fuel air mixture is fed to the engine.

Keep your observations posted.

Cheers!
VJ

Throttle body cleaned, idealing fluctuations gone and crispy throttle response.

Nice, that was a pretty large amount of carbon deposits.
How did u fix the broken air box? Mseal? Plastic heated/melting?
I recently got my hands on a couple of types of tape called flex tape and gorilla tape from the US, nice stuff.. Much better than duct tape especially for such automotive uses. Used to fix panels on my dio
Anyway, try n get a new airbox if possible.

I recently got my hands on a couple of types of tape called flex tape and gorilla tape from the US, nice stuff.. Much better than duct tape especially for such automotive uses. Used to fix panels on my dio
Anyway, try n get a new airbox if possible.

The idling orifices, injector ports and IAT sensors collected up a lot of carbon deposits. Most dukes have those unstable idle issue, cleaning up the throttle body will definitely make a difference providing stable idle and will make the bike less prone to stall in bumper to bumper traffic.
We used solvent based gasket maker silicone for those cracks.
Nothing to worry the cracked area is a separate chamber for PCV system. Its just plastic welded, actually the airbox is of pretty good quality. Only that small chamber alone is made of some crappy ABS plastic.
Just cleaned those oil vapour traces with carb cleaner and used solvent based silicone from "anabond".
Now it's fine..

Throttle body cleaned, idealing fluctuations gone and crispy throttle response.

These days anything with the name Gorilla seems to be having the upper hand, eh. (pun intended). Heard about the flex tape, but the Gorilla tape seems is a new one to me. Nonetheless, both are available here in India I guess. Might probably be fake, but hey..





Imam and team that's a sport of doing a DIY. Did any of you guys care to clean the injector and did anyone have the time to check the holes that the injector has? Nonetheless, the fuel quality we get here in India definitely warrants a timely cleaning of injector and and throttle body, which I've iterated many a times here in this forum. Most of the throttle lag, vibrations at certain RPM and poor idling and stalling can be mostly almost nullified by a thorough throttle body clean, hoping no other gremlins are playing catch up.

Good sport there, fellas.

Cheers!
VJ

These days anything with the name Gorilla seems to be having the upper hand, eh. (pun intended). Heard about the flex tape, but the Gorilla tape seems is a new one to me. Nonetheless, both are available here in India I guess. Might probably be fake, but hey..