I have an old Brigg's and stratton Eng and i would like to know how to set up carb . it has two screws on it
Answers:
Try an initial setting by closing the jets completely (lightly seated). Open them 1 1/2 turns .
Most of the small engine manuals recommend this procedure after cleaning/rebuilding carbs.
One is for throttle position/tick over, the other is for mixture/petrol.
Set the tick over, then turn the mixture until the speed increases or is at the maximum,
turn the tick over down so it idles at the lowest steady speed.
Repeat untill adjusting the mixture just decreases the speed or makes it lumpy.
You will then be close to optimum.
The screw on the Float Bowl is about 2 1/2
The other is about 1 3/4
Run engine, set revvs to required level then adjust air screw until engine runs evenly
the petrol screw is adjusted to set suitable idle speed, usually the lowest possible but must idle smoothly.
the air mixture is adjusted to the highest level that allows smooth operation across the rev range.
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