I recently bought an LO206 kart and have taken it to two Test&Tunes at our club’s track. My class requires the yellow carb restrictor and I didn’t put it in until the second test. I lost about 250 max RPM on the straight and about 1.5 seconds off my laps. Coming out of turns there was a lot of hesitation with the throttle. What kind of adjustments can I do to the carb to make it run better with a restrictor? Also, It would hit the rev-limiter at the end of the straight without the restrictor but with it in it got to about 5800 rpms. Do I need to re-gear it at all?
Almost certainly so. You could add a couple of teeth to the axle sprocket and see how it responds. Keep adding teeth until the times stop improving (assuming you can put down consistent laps).
Here’s a guide from Briggs on setting up the 206/animal carb:
There are some specific changes that are sometimes made when you move to the yellow slide from black, but I’m not 100% confident on what they are, so I’ll wait for someone else to chime in.