Had to rebuild my carby on a 091202 engine as it was running rich AF. Found the diaphragm was almost hard rubber (see hopefully attached), which was the reason it smelled like a petrol station when i used it and fouled plugs in 3 hours.
I reinstalled, turned the screw out 1 and half turns (it was originally turned full in), but realised the screw was vibrating when I was turning it in and out. It then started backfiring.
Is my screw supposed to have a spring on it? If it does, then it will not allow it to 'seat' and the one and a half turns would be pointless.
Hopefully makes sense and thanks in advance for any feedback

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