I recently, March of 2019, bought a 1994 K 75S. At this point, I've been able to ride it over 2000 miles, between endless rainstorms here in the north east. Here are some initial observations and comments.
I am really enjoying the light, nimbleness of this bike. The original owner installed progressive springs, and a upgraded rear shock. Not sure how bad the OEM suspension was, but the aftermarket components work fine.
Smoothness of the engine is uncanny, as most of you already know. I've never had a machine that is this vibrationless. Only downside is when I get back on my shakin' 850 Moto Guzzi Le Mans.:)
The K75S does not create as much rider heat, as I had expected. I had been under the impression that k bikes were hot to ride in warm weather.
Gas mileage seems to be unexpectedly great. After several fill up, my gas mileage is coming in at a low of 50, to a high of 53 mpg. This is in all types of riding, plus some 75mph + sprints. Been using mostly premium fuel.
Tires are a sore spot, as the bike came with 4 year old metzeler non radials. They are OK, but I prefer to run Radial tires. can I use radials on a 94, with the three spoke wheels? Any specific tire recommendations ?
Overall, I am very impressed with this machine, and frankly, very surprised that the K75 was not a huge sales success for BMW.