Poppy at light deceleration

Bike: 1979 KZ400 with 2-1 carb manifold and a single VM34 carb.

I'm getting a very slight popping at light deceleration. If I let off the throttle completely, no popping or backfiring, but if I lightly let of the throttle (when at cruising speed), I hear a very slight popping sound. Only while decelerating, not while cruising or accelerating.

Does this sound like my needle is lean?

Sure does! raise the needle a notch and try it again. Good luck! Paul