what exactly happens to your engine mate? does it just die after start up?

if it just keeps flaming out other then maybe having idle set to low, increase idle by 1/4 turn and see what happens if still nothing then you could try pressure testing your system.

take off line from carby and pipe outlet block one end of the lines and presurise see if you have a leak - then check pipe that pressure nipple is not blocked.

see how you go.