Noticing a cold start idle and warm up issue this season

This is my First time bending the ear for guidance here. I have a ‘16 939 I bought new in the summer of ‘17. It’s been a love story thus far aside from a couple missing screws here and there. This season i started to notice upon a cold start, after pulling it off a ctek mus 4.3, that the bike was idling different than it had before from the exhaust note specifically. There’s the typical deep exhaust tone that’s somewhat growly which sounds normal to me, but after about 10-20 strokes that sound would go away entirely and the sounds was almost “dry” which is the only way i could describe it. The repeated growly patter goes away. It was a much higher note without the tailport growl. At the same time the headlight will flutter like it’s on the verge of a stall but the engine doesn’t sound like it’s about to stall necessarily. Once it’s warmed up it seems to be okay and normal idle.
I replaced the battery a few days ago as it was coming due anyway. The old battery was still testing within range after bleeding off excess charge but I couldn’t leave the bike off the ctek for more than 2-3 days without being non startable. I didn’t think this was the issue to begin with necessarily but was also considering the rectifier/regulator. The regulator has a superceeded part number and some newer models have been fitted with mosfet vs. shunt but can’t confirm with dealer on a FA022AA. So I haven’t completely ruled out electrical just yet.
The bike consistently holds coolant level, the oil pump appears to function properly as the sight glass is nearly clear while running so I can only assume the oil is cavitating properly, but what do I know, I’m not a doctor. I do know that with 15 years of audi/vw experience, little should be left to chance when something doesn’t sound quite right or normal.
Maybe I’m being hypersensitive (every pun intended)to this but i thought I’d still ask around just the same. I know, at least from cars, that fuel pumps or clogged pickup tubes have caused similar running issues or even exhuast flaps Potentially.
A couple years ago i kept hearing a tinny rattle from the exhaust when idling and riding and come to find out that a screw for the exhaust heatshield in front of the rear wheel had fallen out. Fortunately the cage nut behind the shield was still there after a few weeks of riding so that’s how i got here.

Anyone, thanks in advance.

Check your grounds, I dunno about the sounds but I was noticing my bike was having a hard time starting a while back and wrote it off as the battery having Covid. A few rides later the bike freaked out and went into limp mode. I pulled over and couldn't find anything, started it up and rode home. Next day I want through it and it turned out to be a loose negative cable at the battery terminal. Worth checking to see if the ground wire is tight where it terminates on the engine and confirm there's no corrosion. You can check on the regulator type for you model year by looking up parts on Ducati Omaha's site. The upgraded regulator is better but I don't believe it's a true Mosfet, though looking at it, I believe a Mosfet would be plug and play as an upgrade. I was pointed to this site - Home however my 939 SP does have the newer R&R so I'm not bothering, for now.

I think I may have potentially narrowed it down to a fueling issue albeit the pump and or thermistor. The bike starts strong with the new battery, but still strokes oddly until warm. If it were electrical, i wouldn’t see it changing when warmed up if not even getting worse. I’m going to speak with the guys in svc. when i take her in for tires this weekend. I may check the fuel lines for kinks over the next couple days or if i feel up to it drain the tank and start from scratch. Who knows.

When my OEM starter was on it's last leg, she chugged slow until warm. This was just after I installed a LiFe battery, so wasn't the amps. Lot of weird ailments with the crappy non-Denso starters.

gatdammit said:

When my OEM starter was on it's last leg, she chugged slow until warm. This was just after I installed a LiFe battery, so wasn't the amps. Lot of weird ailments with the crappy non-Denso starters.

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I would have never imagined a starter, especially once the bike’s running. I wonder if the solenoid is still pulling charge away from the stator and or rectifier? Guess ya never know with some of the Euro machines.
How long did the OEM hold out before replacing?

I changed mine at around 16K. The new battery at about 12K helped. I was having to warm the battery (high beams on) for up to 5 minutes that last winter on a cold morning start. Kicked over better once warm.

gatdammit said:

I changed mine at around 16K. The new battery at about 12K helped. I was having to warm the battery (high beams on) for up to 5 minutes that last winter on a cold morning start. Kicked over better once warm.

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Man, it’s either indicative of our crappy riding seasons in the Midwest or I never go anywhere. My ‘16 is only sitting at 6650 mi. as of yesterday and i ride just about everywhere when the suns out down to about 40 deg. That is unless, my wife is with me, at that point we drive since she doesn’t like my tarding.
I, for morbid curiosity’s sake, went to Omaha’s site to see what a factory replacement costs. @ $700 and some change I started fishing around for Denso to see what they run (about 200) and found that the Denso and OEM shared the same part number. Further enticing such curiosity, i found a fantastic step by step 821 starter replacement step by step walkthrough over at Ducati.ms. This looks like a great guide. Further in that thread a couple people confirmed that that OEM in cases would be the 27040104A and also confirming them to be Denso motors. There is another part used by Taigene which has the same preceeding numbers but ending differently in 127A as opposed to 104A. It was also advised that the Taigene were not the way to go.
Write up here: Hyper 821 Starter Motor Replacement DIY
I did notice “sales” and “05/04/17” written on the top of the old battery in paint marker so i am about 99% Sure the one i pulled was not what it left the factory with. This would also explain why they needed me to drive another 3 hrs roundtrip to pick up the bike a week later with the old “it needs PDI” talk. PDI is done when the bike comes in from the factory, not after sitting on the showroom for up to a year or more and having 60 miles on it. With Audi we had 30, 60, 90 day refresh/inventory PDI but that wouldn’t require more than a half hour at most if you’re doing a few at a time.
The only thing guaranteed of this bike at this point is the smile factor!
I’ll be leaving mine at my stealership in Louisville (which service has been awesome there by the way) for new Road 5s this week and a 48k so maybe the shop can see what I’m describing once it cools off and the bike sits for a day or two. Thank god I didn’t need tires and esmo/timing at the same time, i know others haven’t been as fortunate.

Thanks again for the responses and suggestions.

Follow up edit: I went out to the garage after posting this morning and snapped i picture of mine. I do in fact posess a denso as the endcap is finned and has silver bolts compared to the taigene which is a smoother non-finned end cap.

It turned out to need a set of plugs. The issue with the cold start turned out to be a misfire and would limp on the horizontal cylinder until warm. Whew! Thankfully it wasn’t the starter or starting clutch. Neither are terribly diffcult to do, but still an *** pain.
Thanks for the advice folks.