You may also have the ignition advanced from where it was previously.

The valves may be tighter than they were (more overlap, less time on the seat, less engine braking) from either wear or from being adjusted properly (now as opposed to being out of adjustment before).

In comparison to what you had before... it may now be "correct" and was "incorrect" before!

Does it run "fast" when at idle? If not, then the throttle adjustment is likely fine. Another common place for high tickover is the choke. Is it fully dis-engaging when the lever is in the full "off" position (do you accidentally have it in the "on" position?)? Is adequate clearance provided between the fast idle cam and the fast idle adjuster?

Was anything else changed in the process of getting the proper needles in the carbs (like a tune-up or replacement coil or something)?


--
Mike!