wild guess: too rich or too lean was my first idea... I would recheck all the specs for the main jet size then a search led me to the idle jet size ... as mentioned below:
https://www.tapatalk.com/groups/racingf ... t1513.html
You need to check the size of the idle jets. They are the pinch at the bottom end of the small tube hanging from the booster. It is common to find these carbs with two different size idle jets.
Another problem common to these carbs is the idle air bleed on top of the cluster is bashed partly closed, sometimes substantially so. It looks to me as if the machine tooling which inserts the main air bleed tube (brass tube pinched at the top pressed into top of cluster) tried to push it into the wrong hole.
Sometimes, the main air bleed tube orifices are different size.
Sometimes one (or both) primary emulsion tube gets pressed into the booster casting a little too far and the 'kill bleed' is blocked or partly blocked. In these carbs the kill bleed is drilled in the aluminum casting at an upward angle just above the inserted brass emulsion tube. The KB is probably .029" or .031", the smaller is preferred, but they both should be the same size.
Naturally, the float level and needle and seat size must be identical on each side.