pilot jet size

So after many many hours trying to get my bike to start, run, accelerate, I have discovered the following:-
The bike is very difficult to start from cold without the use of a "cold start" spray. Once it has started and I have closed the choke, any attempt to increase the revs causes the engine to die.
I have discovered however, that if I very slightly open up the choke, the bike revs very nicely. This makes me believe that the recommended pilot jet #42,5 is not large enough. I live at sea level not up in the mountains. So it is winter at present and maybe that adds aspect to getting it correct.
The situation does improve slightly when the engine is up to full running temp, but before then you just simply cannot increase revs. It does however still feel a bit "flat"
Now, I am a little bit confused over how the air jet/needle works. If you screw it out, does that weaken or strengthen the mixture? They that around 3 turns out from the bottom is standardish. 
Has any one else suffered from this ailment, tried fitting a larger pilot jet, or mastered the air screw position?
Thks in advance
Bruce
 

Turning it out (anticlockwise) introduces more fuel

The recommended starting point for the idle mixture screws is 3.5 full turns from the bottom

My main and idle jetting is standard

Thanks for the speedy reply.
I am making small improvements day by day.
Two cylinders ( one carb ) seem to be running richer than the others. This can be seen on the heavily carboned spark plug. If left uncleaned it causes the bike to run rough and blow back thru the carb. I have left those needles at 2 turns, so let see how that goes.
I have also noticed that once the engine gets really hot, it becomes impossible to start. I fear the fuel atomizes before getting thru to the cylinder, a problem very common on my Ariel SQ4. Maybe a lead replacement additive will help. I do use a zero to 5% ethanol fuel, because I know ethanol is not helping this problem. Keeping the fuel as cool as possible also helps, so I may need to insulate and re route the fuel line. At least I know that the electric radiator fan is working !!