For a period of time my 850 has had some vibration at about 2300- 2800 rpm on the road. This is only noticeable in 4th and has increased more with time, also it manifests itself for the most part through the handlebars. The mirrors are rock steady and instruments are not affected at all. It is a felt thing like more in line with a low frequency heavy sort of sensation through the bars. Anyway going to begin looking through primary & clutch, move into the ISO's, & give the alt. rotor a good lookover. Once I move above the 2800 rpm mark she smooths out as if nothing is amiss, but she is old and I'm going to give her a good check. This zone has always been present but to a much lesser degree.... I don't know.... I shall before it's over.