Use a volt or frequency meter
Be very careful when making gross adjustments to the speed control - make sure everything (especially the Univolt) is "off" prior to adjusting the speed. It doesn't take much to get into an extremely "high" or ""low" voltage situation.
Pay close attention to step #2 in John's post above. The primary speed (frequency) controller is the stop nut on the throttle control (governor)/carb linkage. This correction (primary throttle linkage/speed control) and the carb stop need to be set before "fine tuning" the carb jets.
For a quick check of your existing carb internals, pull both of the needle jets, make sure you can return to the original settings, though (count the number of turns to the stop). The needles on my (old, original) carb were really eroded after 725 total hours.
"Suck it up, spend the bucks, do it right the first time."
WBCCI # 1113
Trailer '78 31' Sovereign
Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
Texas Airstream Harbor, Inc.