Hi Mark Endicott!!
On Tue, 29 Apr 1997, Mark Endicott wrote:
> I have already done all of the other stuff, ignition, valves, plugs
Great!! You CANNOT tune the carbs properly until everything else has
been attended to. Yer on the right track...
> My question (for today) is what is the "BRIDGE" and is this what you
> experienced SU people would do?
Looking down the throat of the carb, you will see a flat area that the
carb needle goes into. The jet is screwed up into the bottom of the
bridge, therefore letting the needle insert into the jet.
What you didn't pick up on was WHY you were to screw the jet ALL THE WAY
UP INTO THE BRIDGE before unscrewing 12 flats.
You have to centralize the jet/needle relationship. This is VERY
important in the early carbs, because the needle can stick in the jet,
causing erratic operation.
Insert the needle into the piston so that the shoulder of the needle
is LEVEL with the bottom of the piston. Assemble the piston/dashpot
assemblies with the carb bases, and get ready to centralize the jets.
Run the adjusting nut all the way up, and then loosen the jet holder
locking nut. Lift the piston all the way up, and let it fall down. If
you hear a soft "shhhhh", then the needle is riding down the jet and
will stick. If you hear a soft "thunk", then you've got the piston
hitting the bridge, as it should, with no interferance from the needle.
Lock the jet holding nut with the piston all the way down onto the
bridge, and TEST it again for the soft "thunk". Then you can turn the
jet adjusting nut down 12 turns, warm up the engine, and commence your
tuning.
TTUL8r, Kirk Cowen
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