[heneste]

If you're running too rich, you'll most likely get black smoke out the tailpipe and possibly increased engine heat. Too lean and you could get backfiring and increased engine heat and lack of power.

Turning the GAV clockwise will screw the adjusting needle into the seat in the carburetor and restrict the Gas flow to the carb (leaning out). Turning it counter-clockwise will open up the passage and allow more gas into the carb (richening the mixture).