Carburettor issue on stuart turner R3MC

I have a stuart Turner R3MC. When I start the engine it will idle but when I increase the throttle it backfires through the carburettor unless I keep the carb flooded by holding my finger on the float. There is also fuel dripping from the air intake screw?? (Brass screw with holes in and notches on) any ideas what the problem is? I can't figure how to get a picture of the carb on lol
Thanks very much,
Aron

Sounds like its drawing air in through the crankshaft seals.