I just wanted to conclude my bit of the story here, and thank you all for the advice. I am in the category: self-employed, not rich, buy cheap used bike, run it till it's completely worthless...basically what Black K1 mentions.

Here in Sweetzerland labor is not cheap. I just changed all 4 coils (dealer refused to let me bring OEM parts) for 1000 CHF, parts and labor.

I think my bike can be sold for 3k, if I'm lucky. Bought it for 6k, 9 years ago.

I will just run it till it dies (gearbox, drivetrain), and then put it in storage for when I'm retired (2041) and need a new time killing hobby...if fuel is still road legal

That 2-3k I'd get from a sale is just not worth the 20-30k km I might still be able to squeeze out of it

An update for posterity...dealer says it's one of the coils...I think he said number 3 but will double check that.

They ask 170 CHF per coil, and reccomend changing all 4 of them and the sparkplugs at the same time...so another 1000 CHF service including the labor at 160CHF/hour. (2 year garantee)

I guess the math is different for everyone, according to their circumstance, but at what point do you scrap the 20 year old bike that is worth 3k CHF max, so that you don't have to pour another 1k into it every 12 months?
-I did a full service at 77k in june 2020 with a head gasket replacement (1200CHF)....bike currently has 79k.

Is it possible to get the same ride that the K provides, but for a lower annual cost? I am not sure really....

At 80k km, how many more years can I squeeze out of her before the main drive shaft fails (which I understand will cost double the whole bike's value to replace)

 ...I used to think I was good at math!

Thanks for that... I do feel that without the tools or the guidance, most maintenance on this bike, or even diagnosing issues is a challenge for me.

I decided a bit of fuel additive 'injection cleaner' couldn't hurt, and did 100km on the autoroute today, but don't think my main issue has improved. It's not too drastic... there is a lack of pick up in the low rev range, the throttle response seems delayed, and revs climb slowly.. But it doesn't seem consistent. It's almost always the case below 2k, but only sometimes in the 3-4k range.

Here's a short clip where you can hear the sound...I wonder if it points more to air flow, the ICV, the coils, a throttle body valve ... Something else?

https://youtu.be/yifzTUv96bk
A second noise sample: https://youtu.be/S0luDqmueh0

Thanks again for taking the time and sharing your expertise!   

As a frequent lurker, and rare contributor, I come with a question for the experts here....I've read through this thread, and am hoping my problem has something to do with one of the two parts Costas mentions...(https://eurokclub.bike/index.php?topic=756.0).

Wait a minute, this symptom describes issue with the idle control system and not the bodies. IMHO your bikes faces an issue with the idle control device s/n 13717705442 or the valve under s/n 11737681005.

Background: K12s 2005, slowly closing in on 80k km....had a head gasket leak last year, and took it to the stealers for the replacement. Following that service, I did a fairly long 7 day tour from Geneva through Livigno, Stelvio etc...and when I arrived home everything seemed fine. Put the bike in the garage for the winter...(I just disconnect the battery for the 4 month hibernation).

Current issue: I got the bike out again a couple of weeks ago, and on the first startup, heard a fairly grindy sound from the timing chain side (all recall services have been done at the dealer, tensioner/oiler). I find that sound has occasionally happened in the past...and not had problems afterward. I figured after a long sit, it was less lubricated on the first turn over. But, now I have what I assumed was 'stuck throttle bodies', but after reading the above mentioned thread am wondering if it's one of the parts quoted above.

Symptoms: Idle seems slightly strange, but not disconcerting, maybe a tiny bit high? Acceleration from a stand still feels like it's missing a beat, or gurgling or something..honestly it makes me think of a chopper's sound...after it passes 2k rpm, it snaps out of it and accelerates as it should, and humms as it should. I rode it for an hour the other day, thinking maybe there was condensation or something causing misfires and that it could work it's way out...but hasn't made much difference. No other symptoms, decelerating is fine, doesn't die at idle. On the autoroute I noticed it sort of lacks power when I try to accelerate quickly....

Any suggestions? I don't have any tools, so I will probably have to go back to the dealer anyway...but was curious if you could help me with a diagnosis.
I could try to add a video if that would help.

Many thanks!

Been a while...I lurk and read here, and often laugh...but had a question recently!

My pillion rider fears slipping off the back, despite hugging tightly...so I started looking for a little removable back rest that could be added to the stock seat...(I have no luggage rack, nor top box)...does such a thing exist? any other suggestions? would prefer to avoid getting a sargent seat just for the add on back rest, as am quite happy with stock.

FYI, I just did a 'big service' on my 05 k12s for 60k km...with two front discs and pads replaced...1250CHF=830GBP. I provided discs and pads at my cost (200 EUR).

I am a big fan of Keith Code and Twist of the Wrist...helped me immensly to understand choosing lines, suspension, acceleration, body position, etc...