Join Date: Feb 2018
Location: Louisiana or Southern England or ...
Acceleration through 2-3K range in first gear should be over in a fraction of a second so hardly intrusive.
That said, what condition are the chain and sprockets in? Badly worn can cause some odd vibes. Aggressive tread tires also (especially at low rpm.)
If neither of the above, I'd start by checking the tightness of all the engine mounts. Next would be checking throttle body synch and checking for vacuum leaks.
07 DL650A, 96 DR350SE, 16 KTM 1290SA, 85 BMW R80RT