This how I used to do it......
when we arrive at the track, we fire up our engine whilst the kart is on its stand to get our engine nice and warm to above 50 degrees! at this point we disconnect the throttle cable from the carb throttle arm and adjust our low jet to either lean or richen accordingly until the engine ticks over nicely at approx 1800-1900rpm, we then then turn out the low jet screw by 3 to 5 minutes approx to richen the engine at this point the engine will often want to stall!! you then re-connect the throttle cable to the carb throttle arm and adjust the throttle cable accordingly to increse the engine revs so the engine again ticks over at about 2000 revs to prevent the engine from stalling on the track!! The low jet screw should normally not need adjusting again. The high jet is best set at about 70-75 minutes, take the engine up to full throttle and hold it there then start and lean off the high jet until the engine revs increases to about 12,500rpm at this point release the throttle (Do not hold the engine at full revs for just a short period of time otherwise you might break a piston ring or worse ultimately damage the engine barrel which can be an expensive repair)
Once your driver gets onto the track they might find that they might have to make a slight minor adjustment the high jet )lean/richen to find the carb's sweet spot!! Suggest you try getting your driver onto the track and adjust the carb high jet on a practice/test days
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