Honda gl 1100 1980 rpm drops too slow down to idle

So I have a problem here
My gl 1100 takes too long to drop the rpm for up shifting or generally
down to idle.
I have rebuilt the carburetor (cleaned and replaced all the rubber
parts and screens with new, I have oiled the diaphragms) the throttle
cable returns swiftly and is not the problem, the vacuum advance from
the back of the engine seems to work fine and no leaks detected on the
way to the carb.
Any thoughts? I am at a loss here!

yarbel RemoveThis @hotmail.com wrote:

>Any thoughts? I am at a loss here!

Most owners are at a loss to how a CV (diaphragm) carburetor works. Your idle
fuel air mixture is too rich because the throttle butterflies are too far
open and
maybe somebody has tried to adjust the idle mixture screws without
understanding what they are doing.

http://www.bikebandit.com/partsbandit/showschematic.asp?dept_id=210652

Item #5 is the idle mixture screw. Turning it clockwise leans up the mixture,
and that's what you want to do, if you or any previous owner has tried to
adjust the
idle mixture screw without an understanding of how the idle mixture circuit
works.

The idle mixture circuit gets fuel through the idle jet and it gets idle air
through the pilot air jet which will be in the mouth of the carb or
underneath the diaphragm.

The idle gas and the pilot air mix, and then the idle circuit splits off.
Only about 1/4th of all the fuel air mixture goes to the idle outlet port
that is controlled by the
idle mixture screw underneath the carbs.

There are three OTHER outlet holes just underneath the bottom edge of the
throttle butterfly. They are called "transition ports". The purpose of the
transition ports is to feed the engine extra fuel air mixture as the engine
vacuum downstream of the butterfly drops off when the rider opens the
throttle.

Three quarters of all the gasoline your Old Wing needs while cruising down
the freeway comes through the transition ports.

If nobody has ever tried to adjust the idle mixture screw, the transition
ports will still cause problems, because the single fuel air outlet port and
passage gradually gets clogged with gum and varnish and somebody along the
line will turn the idle SPEED screw up, uncovering the transition ports.

Then, when somebody cleans out the carbs, they make the mistake of trying to
set the idle mixture by turning the idle mixture screws counterclockwise.

They think that the idle speed should increase the more they turn the screws.

Finally, they get the idle mixture so rich, the idle speed slows down, the
exhaust sounds becomes dull and thudding, and they have to turn the idle
speed screw up to increase the engine RPM and then the carb gets gasoline
from the
transition ports when the engine just doesn't need that much fuel.

The whole idea of adjusting the idle mixture is to get the engine to idle at
a slow speed by turning the idle SPEED screw down and covering up the
transition ports with the bottom edge of the butterfly. You cannot adjust the
idle mixture if the transition ports are uncovered.

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