I don't know what "Umritzelen" is but if you mean changing of the sprockets to get a different gearing; yes, it's possible.
If you want to keep the chaincase you can put on a slightly smaller rear sprocket(33 t, standard 35). If you discard the chaincase you can make bigger canges (29 t) but still only the rear sprocket. Isn't enough room in front to put in a bigger sprocket there.
If the engine rev 4000 rpm in a given speed, it's reduced to 3300 rpm with the 29 t sprocket; that gives a significant reduction of fuel consumption!
Gruss Lars