1.4 carb keeps changing mixture?

Just a quick one for all you Carb runners out there :thumb:

When i bought the daily Nova (1.2 Saloon running carb) it wouldnt idle correctly and would not start in the morning, full choke no throttle and i wouldnt fire up. Anyway got it to the garage and put it onto the emissions tester and it was running very very weak, 0.2 on the Co scale, anyways after tweeking the mixture upto around 2.5 it ran absoloutley perfect, started first time in the cold with choke and ran like a dream, but after afew days it struggled to start again, put it back on the emissions tester and it had dropped back down to around 0.4, quick tweek again and runs sweet now, it just seems to keep changing its own mixture, the screw itself isnt wobbling itself in or out so im pretty stumped :(

Anyone have any ideas what it could be? Something internal? :(

Air leak on the inlet manifold.

Would this cause it to splutter and have a flat spot when i put my foot right down too?

Sound like you may have some crap in the idle jet. Worth a can of carb cleaner, remove the idle jet and spray it until it comes through with no issues. The idel jet is the one you can see in the top of the carb when you remove the air cleaner.