Hi,
My son is in Cadets LO206 (2nd yr cadets, 1st year with our own kart) and I completely understand that the most time to be gained (seconds) would be driving improvement. I am curious though, if there was a choice between carburettor tuning or new tires, where would the most time gained come from between these two (no sitting on the fence 
)?
Tires will certainly net more lap time if the driver can use the extra grip. But carb tuning is free and tires cost money so I’m not sure why you need to choose? And the tire advantage wears off eventually.
Driving saves seconds, chassis tuning saves tenths, engine tuning saves hundredths. Unless your carb is really messed up it shouldn’t make seconds of a difference, it is free though, as mentioned above. Make sure it’s straight with the engine, set float height and all that, takes like an hour max, and builds consistency in the long run. Tires could make a huge difference depending on their condition, but again as mentioned in the previous comment it is temporary. The only real gain you get from tires is if you use a set of tires for 1 or 2 races and buy new ones, Start with the carb tuning, if that doesn’t satisfy your time requirements do tires next. They’re very different things and neither will make a significant difference without consistent driving.
It’s a bit of a “how long is a piece of string” thing.
Depending on how “bad” your tires are… you can pick up as much as a second.
Carb, tenths maybe unless it’s way, way off.
Let an engine builder find a baseline for your carb and put on new shoes, if budget allows.
There’s no magic in cadet carbs. If the cap is ground to allow max opening of your slide and the float is somewhere near 0.875, then there is no time in tuning a carb.
Derek. I disagree. I think it’s worth 2 tenths just telling a cadet driver that you had an amazing tune done to the carb and it will definitely make more power. No money needed for that one.
How old are your tires? The money is better spent on tires. The question is do you need them. In our first year in cadet we went all season on one set of tires. And we did a lot of laps on them.
You got me there!!! Absolutely worth 2 tenths.
Thanks for all your replies and opinions. Much appreciated. I went the route of cleaning the carb and checking float height. Much cheaper option!