Topica Loopframe_Guzzi Archive
 

Subject: RE: adjusting carbs

Author: Jeffrey Buick

Date: Mar 3, 2004, 9:34 AM

Post ID: 1716203093


Joel,
For a Guzzi you would only need 2 gauges, one for each carb. The set
ups that have 4 are for a 4 cylinder bike with four carbs. The basic
theory is that you want to make sure that both of your carbs read the
same amount of vacuum throughout the trottle range. Vacuum equtes to
how much power you are trying to get out of the engine and it needs to
be balanced across all carbs/cylinders. The reason the bleeder screws
were mentioned to use is that they restrict air quite a bit and would
help steady the vacuum gauge needles so that they don't bounce all
around when you are trying to read them. I believe that if use buy one
of the set ups that use columns of mercury then you won't have a problem
even without the bleeder screws. You would start by setting your idle
vacuum equal at idle by adjusting the throttle slide stop screw.
However, once this is set you may need to adjust your throttle cable
length adjustment screws (either on top of the carb or at the throttle).
You need to make sure that the throttle slides start opening at the
same time so that your vacuum will be balanced across the throttle
range. You'll get the hang of it.
Good luck.
-Jeff


joel urruty wrote:
 
There is a screw on each manifold. I think would like to try the vacuum

gauge to set the carbs. I went to jcwhitney's site to check out the
vacuum gauges. Do I need the 4 gauge one? what do all the guages do?

do I need to get a special hose to connect it to the manifold hole?
You mentioned something about brembo bleeder screws, aren't they the
screws on my brake with the funny nipple?
Once I get the vacuum gauge on what screw should I be fondling? the
pilot air screw (the small one flush with the carb) or the throttle
slide stop screw ( the larger one that has the exposed spring).
You may be rolling your eyes right now as you can see I am new to this.

Thanks, Joel


kcampbellNH wrote:
 

I find the best way is by vaccum. You need the "mercury sticks" or just


two accurate automotive type vaccum gauges work too.If you use vaccum
gauges you will need something to pinch down the hoses to dampen the
needle fluctuations. You can use two brembo bleeder screws to screw into


the manifolds to get your connection. I have an inexpensive J C Whitney
carb balancer set (4 Vaccum gauges mounted to a board). First make sure
you have some slack in each throttle cable. 2, warm-up engine. 3, bring
rpm's up to approx 3500. 4, adjust cable adjusters until both cylinders
read the same (make sure you still have a couple MM of slack when you
are done). 5, bring to idle. 6, adjust both mixture screws to best
idle. 7, adjust the idle stop screws until you get the desired idle and
gauges read the same. 8, repeat steps 5, 6, 7. Don't worry about the
suggested settings. If they don't balance you likely have some small jet


or passage way in the carb plugged with swarf. Some may disagree but
this procedure works on anything. Good luck and ride safe.
Kevin

98 EV
97 Sporti
80 v50++
75 T-3
74 Eldo



joel



Jeff Buick
Detroit, MI

1972 Eldo LAPD
1974 Eldo LAPD
1974 Eldo Civilian
1972 V7-Sport

Entire thread: