Posted by chris case on Saturday, September 11, 2004 at 5:16PM :
In Reply to: Re: Accelerator pump? posted by Brian in San Mateo on Saturday, September 11, 2004 at 12:17PM :
I know that guys who sell NEW carbs are particular about shaft fit, folks who sell rebuilts are not. Biggest problem I see with loose shafts is air leakage, but the idle mix is adjusted to compensate.
If not your accelerator pump, it could be a plugged transfer port. Basic carb tech: there are 4 ways for gas to get into throat: accelerator pump; main jet directly to venturi; mainjet through idle circuit; and also a mainjet through idle jet to transfer port circuit. If you have an unmounted carb and look in from the bottom, you should see the idle needle protruding from the idle port. Next to it slightly above is a slot- this is the transfer port. As the throttle plate passes it, more of the slot is exposed to vaccuum under the plate, allowing progressivly more fuel into intake. If this port. or the idle jet, or it's connecting channel are plugged, it can produce lean spotts in the-just-off-idle stroke. Since the transfer port is a branch of the idle circuit, you can try some unique fixes. In Mexico (and anywhere else too) you can try crossing plug wires to make it backfire, hoping the intake charge blows back through the carb clearing the idle /transfer circuit. Or maybe pulling the idle needle and give it a shot of compressed air (watch out for gas blowing out of the carb allover).
Or maybe it needs a tune up, or has a valve going bad, or is out of time, or is burning the points.....
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