@Covrox :
After about 9,000 Km on a '22 C 400 GT and about 16,000 Km on a '23 C 400 GT, sure, I have a few thoughts ...
Gas Cap:
1) Not to insult your knowledge, but just trying to cover all the bases: you realize that you have two minutes after turning off the engine to open the gas cap? (After that interval, there's a routine to follow, with the key fob nearby, to open it, too, but I have never tried that out.)
2) The spring-loaded latch needs to be oiled periodically, or it gets sticky and won't work. This happened to me, and I now try to remember to do this -- oil the spring area, hinges, whatever else is the area -- periodically, once a year or so.
This issue has been discussed either on this forum or another Beemer forum I sometimes check in on (BMWLT.com), I can't remember which (a bunch of Beemers use this same cap).
OTOH, 3,000km seems pretty soon for this maintenance need, unless the previous owner left the bike out in the rain a lot, or something like that. Or maybe you really have a defective cap.
3) Always a good idea to carry a T25 in the top case (if you have one), or under the seat, etc. Gets the gas cap open regardless of any malfunction, allows access to the battery for booster packs, etc.
Exhaust Pops:
I don't believe I've experienced this.
1) At 78 years old, my hearing is piss poor. I wear hearing aids off the bike, and custom-molded silicone ear plugs while riding (to attempt to preserve what little capability is left). Bottom line here is that I'm probably the least able person to comment on bike noises.
2) With extremely rare exceptions, I use the highest grade gas, because in my region (upstate NY) there's a chain that has ethanol-free gas, but only in that grade. And I really don't want any ethanol in my bikes or car (or snowblower, lawn tractor, etc.), if I can help it.
I mention that because I wonder whether your exhaust issue is related to the gas you're using. I know, kind of a stretch.
3) Maybe some bad oxygen sensor or something like that, or maybe the bike's software needs updating. Sounds like a job for a warranty fix by the dealer.
TFT Screen:
1) See that "hearing" caveat, so I can't comment on any noise. I think I would've have noticed any vibration, though, and I have not, neither on my '22 or '23.
2) I've had Cymarc's anti-theft device (
https://www.cymarcbikeparts.co.uk/bmw-c400gt-tft-screen-security-brace-1610-p.asp) for two years now, and I wonder whether that might help you out, in terms of vibration.
3) Sounds like a job for a warranty fix by the dealer.
Engine Vibration:
1) See Exhaust Pops.
Front-End Rattling:
1) I got nuthin'.
Poor Quality, China vs. Germany, etc.:
1) I had my entire '22 replaced by a new '23 by BMW. You can read about my saga in this extremely long thread I started:
www.bmw-scooters.com/threads/bmw-swapped-out-my-used-22-c-400-gt-for-a-brand-new-23-c-400-gt-free-part-i-of-ii.2932/
And I've read a couple of posts here about some other folks with engine problems.
So there's that.
OTOH:
2) People tend to post about problems, not about things that work as intended, i.e., the internet magnifies issues.
3) Beemers produced in Germany, or Czechoslovakia, or someplace in Europe, are not problem free, either. On other Beemer forums (I owned an R850R for three years, in addition to the scooters) I've read a lot about shaft final-drive failures and other issues, for example; there's now some sort of periodic replacement program for that. And the adaptive cruise on the latest high-tech RTs and GSs never seems to work properly. And so forth.
And nearly every brand of bike issues recalls. For a while, some expensive Ducatis were sold with gas tanks that got deformed by ethanol-blend petrol.
So I'm not convinced that our scooters' being made in China has much to do with anything. Not the whole bike like our C 400s, but various parts of almost all manufacturers have come from all over the world for years now.
On the Third Hand:
Me, I don't see how BMW sells
any of the C 400s in Europe and Asia. If you look at the offerings of Zontes and Voge -- which you and I can't get in North America -- in the 350cc - 400c displacement range, you can see that they are chock full of more features and more storage, at thousands of euros less than the C 400s.
About the only thing possibly better on the C 400s is that it may stop better, having two discs up front (as I think all the big Zontes and Voge bikes have only one disc, but I could be wrong).
But unlike those other brands, the Beemer has much less storage, doesn't have cruise control, and while adding TPMS is possible it's not even offered as a factory option when configuring a new scoot. (You can read about my journey to add internal TPMS sensors to my '23 in this post:
www.bmw-scooters.com/threads/2025-tpms.3557/page-3#post-30463 . It took about a year's research for me to make that happen.)
And the C 400s don't even have a parking brake!
So what does BMW do? It adds puddle lights as an option (which I'd bet
no one asked for).
And as you say, the C 400 is never advertised. When BMW brings a tractor-trailer full of demo bikes to a rally or a dealership, there's no room for a C 400. And it's never mentioned in the emails I get from BMW, touting sales, financing, new features on other bikes, etc.
Also as you say, though, the C 400 has a lot of get-up-and-go, reasonable seat height, reasonable weight, and I think it's the best handling bike I've ever owned. So it is fun to ride, but I'm sorry to read about all your issues. I hope you get them all sorted out, and all under warranty. Good luck to you.
[By the way: if you're reading this on some device that doesn't show forum signatures, you might be interested in my gallery of C 400 GT farkles, at
https://billanddot.com/C400GT/ .]
