I don't know. R1100 transmissions have always been known as clunky devices. I am wondering if anyone has had luck with a different transmission oil or if there is a secret to adjusting the linkage. I have had the bike for 7 years after many, many years of slick shifting Japanese bikes and still can't get comfortable with the tractor trannie in my BMW.
Beemer person here, having owned 5, all 'R' series except for a K1200 LTC, so here's my humble opinion:
Since the gearbox is separate from the engine oil, you can try different weights but please don't use a synthetic oil or you may 'cause' oil leaks:surprise:
Synthetic is so 'slick' that it has a tendency, especially on older high mileage BMW's to seep past gaskets and O-rings:sad:
Believe it or not, some mechanics confronted with leaks to repair, tighten all nuts and bolts and use a 'Dyno, non synthetic' oil and the gaskets and O-rings will 'swell up,' and sometimes stop the leaks cold:grin:
Most Japanese bikes use helical cut gears, which most of the time feel smoother when shifting. Straight cut gears, while durable, are a bit more clunky in feel. Either will get the job of shifting done. I wouldn't worry too much about it and just enjoy the ride.