weber carb overhaul

evening,

i need to give the carb a good once over.

it runs rich one day , normal the next - had her up on axle stands at the weekend, was a swine to start before lifting and perfect when put back on its wheels so assume crud in the carb.

any suggestions as to what to do, any tricks i need to know ??

i assume the co2 screw is the usual 2 and a half turns out….