I have seen wheel type things used on webers called a throttel plate (i think) you can adjust it if the cable is a little long or short.
If your going to keep the current jets you may as well keep the std carb. As I said I have a weber on my 4ac with the std jets, it kept fouling plugs (have that fixed this a stronger ignition system). I also get very poor fuel economy, I get roughly 300-350km's out of a tank, this is 80kph highway driving.
has this scared you into getting it rejetted yet? :blink: