Those carbs work very well on my Atlas, but plenty have had issues. Following Piet's mate's advice, I dialled out all accelerator pump action and that smoothed out off-idle acceleration a lot, but there's still a tiny bog off idle, easily ridden around, but I am going to re-add the minimum accelerator pump effect to try and tune that out. BTW, jets are available plus carb parts from Fiat and Alfa places. There is one place in England and one in Melbourne, Oz.