If I may be so bold....
Check the torque of all your major mounting bolts... the wheels, the frame, the engine.
If all ok, does it do it with the clutch disengaged? If not, there's something in the engine, drive train.
If so, it's in the wheels, tires, chain/sprockets, forks, swingarm, etc..
At different speeds, different harmonics are created. They are amplified by whatever "sings their song"....
