Thanks CR750, the screws on those are on the engine side of the venturi so fuel instead of air adjustment. I was forgetting that 
No problem, these variation in carbs can be confusing.. 
Yep that caught me out as well. Trying to get the fueling correct on the F2 it was just going richer and richer until I asked the question on here. Sorted first go after that. Thats the great thing about this forum, finding the small but vital bits of information as well as the big stuff.
