I usually avoid the freeway because you miss a lot of countryside and that is what my riding is all about. I went on a ride yesterday which just happened to go right up the freeway. At about 65 mph, 3000 rpms in 5th gear on my 1987 FXRS, there is a vibration that comes and goes. It seems to start in the seat and work its way through the entire bike. It doesn't occur at 55 mph but I would like some ideas on what to check. I'm planning on checking the drive belt and the primary chain. Any other ideas on what could be occurring or what else to check would be much appreciated.