Idle mixture screw on bing 64
in 912 / 914 Technical Questions
14 years ago
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Re: Idle mixture screw on bing 64
by Rob Seaton » 12 years ago
The Manual is correct but maybe clockwise and counter-clockwise is not the best terminology to use as it can be misleading depending on the observers point of view; looking up at the bottom of the carb or from the top as you would normally do when the carb is installed on the engine.
The manual may be changed to something like this:
Leaner mixture is when you turn the idle mixture screw IN.
Richer mixture is when you turn the idle mixture screw OUT.
The idle mixture screw is not strictly an air adjustment or a fuel adjustment; it is a combination air/fuel adjustment. the fuel is mixed with air at the idle jet and the atomized fuel is routed to the small holes (ports) slightly downstream of the butterfly sealing surface.
The idle ports are two holes that are close together but slightly staggered at the sealing surface of the butterfly. These are not adjustable.
The idle mixture port is slightly downstream from the butterfly and is adjusted by the idle mixture screw.
see crude cutaways in the attached pdf.
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