Subject: Re: Setting Carbs
Author: Bruce Giller
Date: Feb 18, 2005, 12:16 PM
Post ID: 1718416037
Many moons ago, I asked Godfrey G. about how to set the carbs on my Eldo
and have been using his method every since.
Bruce
'72 Eldo
-------- Original Message --------
Subject: Re: More Eldorado questions
Date: Mon, 22 Apr 1996 20:49:30 -0700
From: Godfrey DiGiorgi <rama-@apple.com>
To: bgil-@mitre.org
CC: euro--@onpmomma.isc-br.com
Can't answer your electrical or air filter questions since I have no
experience with Eldorados. However, there are two screws per carburetor
on the VHB30s that you need to make adjustments with as well as the cable
stops.
You have three things to setup:
- mechanical synch of the cables
- idle speed
- idle mixture trim
(This assumes that the float levels are correct, both cylinders have
good compression and the valves are adjusted correctly, and the ignition
timing is set up correctly first. Carburetors are the final part of a
tune up and should be adjusted when the motor is warmed up thoroughly.)
The method outlined in the old Guzzi manual works with a little bit of
effort but it's much much easier to do these adjustments with a set of
vacuum gauges or mercury carb sticks and a nice shop tach if you have
one handy.
Basically, the way you do it without a vacuum measuring device is
to back out the idle speed screws all the way and set up both cables
so that they have an equal amount of freeplay (about 1-2mm). Then
screw in the idle speed screws *evenly* to an approximate setting,
making sure the amount of play in the cables remains equal.
Turn the idle mixture screws all the way in until they bottom lightly,
then back them out the prescribed number of turns the Guzzi manual says to.
Now start the engine and turn the idle speed screw in or out, evenly, until
you get a proper tickover speed. At this point, one carb at a time, turn
the idle mixture screws in and out by 1/4 turn increments and hold them
there for about 15 seconds at a time, noticing when the engine rpm goes
up or down or firing gets smooth or uneven. I usually set Dell'Ortos
about 1/8 turn out from the highest idle speed.
Now readjust the idle speed screws down or up until your normal, stable
idle is obtained.
Guzzi's method of determining proper mixture and idle speed is to pull
one spark plug wire at a time with the engine idling and count how many
pulses fire before the engine stalls. Usually about 5-6 is considered
right. You can also set the idle mixture, one cylinder at a time, but
with the idle speed screws turned in a bit to keep the engine going,
then back them out evenly to get the final result.
I usually use the mercury sticks to set my synch and idle speed balance.
Connect them to the inlet stubs and start the motor. Turn the
idle speed screws until both are even, then open the throttle just a
tiny bit and adjust the cable freeplay until they're even again. Do the
idle mixture screws the same way as above. It's a bit more precise this
way and much quicker.
No matter which method you use, when you're done be sure the cables have
2-3mm of freeplay and are not binding as you turn the steering.
Godfrey