Too much vibration only @ 5K-6K RPM?

[Hillbanger]

This is a recent developement.  4K RPM The bike runs smooth like normal, then right at 5K,  the vibration rattles my teeth and the mirrors buzz like angry bees.  It keeps the same vibration until I come out of 6K. It smooths out some at 7K and higher, but the buzz, in a lesser degree, is still present at higher RPM.  

Since this is a recent development, I went ahead and changed the oil out, with full synthetic, it was close to due.  That helped a little, but it still doesn't run like it used to.  In Neutral, a quick flip of the throttle yields some hesitation and stutter at the 5K mark.  It used to be able to run up the throttle real smooth, so I know there is something different now.

I took it to 3 different shops and nobody knew what to make of it.  They reved the engine, and said "yep, there's a lot of vibration".  Two of them suggested motormounts.

I haven't replaced the plugs yet.  I just put new ones in about 2k miles ago.  I also haven't changed any settings or added or removed any parts.

Anyone have any ideas or experience with this one?

[Red01]

First thing I'd check is that nothing has worked loose. Motor mounts, foot peg brackets, etc. While you're doing that, check the condition of rubber mounts & grommets in those same things.

[Egg 'n' Bacon]

While you're changing plugs, do a compression check too.  May also be worth checking the carb balance.

[B12Teuton]

Strange, I thought they vibrated worst around 4300rpm.  That's where mine was bad.

[fake]

my fairing is the only thing that vibrates