Been riding my new to me 2014 FXDB around and noticing that she vibrates differently in different gears. Specifically, acceleration and cruising seems to be the smoothest in 3rd and 4th, but she does not seem to like being in 5th or 6th gear if I'm doing under 70mph. The engine goes from normal vibes in 4th gear to weird staccato vibrating once I shift into 5th. Even above 70, I am noticing the bike vibrates differently in the higher gears, noticeably so.

Is this normal? I've read that the 5th gear is different from the other gears somehow - I think it said elliptical shaped? 5th and 6th gear seem to vibrate a LOT more than the other gears. (And it's not a case of being in too high a gear for the engine speed, I'm noticing this at all speeds). In 6th gear at 75mph, my pegs vibrate to the point of being uncomfortable.

This is my first EFI/6 speed bike and am still getting used to it...

 

pull in the clutch and let the engine idle down at the problem speed(s). This will help isolate the problem. If the vibrations go away, it's the drivetrain (maybe normal, maybe isolators, tune, or engine alignment.). If not, it's the chassis (wheel balance, alignment, bearings).

The chassis should be effectively glass smooth. The drivetrains in Dynas vibrate more than the other Harleys.

 

How many miles are on it?
I have an 09 FXDF w/ 13k on it - smooth as silk except she likes to be at 70+ for 6th gear. The wife bought a 15 FXDB last year, new. I rode it and thought something was wrong - rode rough and vibrated a lot (compared to my bike) - but didn't seem to mind being in 6th at 60. I asked the dealer and ppl here, they said let it break in some. I thought they were full of it. Sure as hell, it did smooth out (only have 1500 on it now). BUT, she has mid controls and hwy pegs - the hwy pegs do vibrate my feet a lot more than my 09.

 

The Dyna is vulnerable to her alignment. I had my drama with that and needed to replace the front isolator and do a vehicle/engine alignment at 600 miles; bought the isolator and did it myself, dealers don't ever touch my motorcycles. I had to shim out the front isolator to put it in the correct position it needed to be in to prevent it from collapsing again and contacting the engine bracket. Since then, with a new isolator and correctly aligning the bike, she's butter smooth.

Check that front isolator and your alignment... A far too common problem on the Dyna; HD is fully aware of their screw-ups during assembly...

 

If you take it to a dealer most will tell you "they all do that".