In 6th gear, when the engine speed is steady at around 3800-4000 rpm (around 70 mph), I can feels a sort of rhythmic resonant buzzing coming from the engine. I feel it through the pegs and seat? not through the handlebars, and the mirrors do not vibrate with it. Above and below that speed, it disappears. It is not noticed when in other gears, or when coasting at that speed. Any road defects or wind buffeting and the "resonance" is not noticeable. The frequency of the "resonance" is about 70/min.
I am thinking that this is probably a normal thing??? just related to the confluence of gear and engine speed, but just thought I'd ask. 2009 r1200r, 25 k miles. I did not notice it until a recent trip.
It is noticeable enough that I can tell when I am at 3800 rpm just from the feel, ie, do not have to look at the tach