I have just purchased a 2004 R850R and need to know how to reduce the seat height. Any information would be greatly appreciated.
If it's like my 97 R1100R, take the driver's seat off and flip it over - you should find an allen wrench clipped to it. The seat has a bracket towards the front, which sits on the two cylindrical rubber mounts located just behind the tank. You should be able to see how these rubber mounts can be moved (what the allen wrench is for) so that the seat height is lower.
Mark