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Hello all. Looking to adjust my carb settings after fitting velocity stacks to the sucker. I'm having trouble finding the air/fuel mixture screw though. Should there be a screw for each air intake valve? (four velocity stacks thus four separate screws?) or is it one screw for the whole carb setup? Oh and the bike is a 1980 suzuki gs550
 

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Most often folks adjusting carbs, start at the idle end. The carb adjusting guide, says to start at the main jet first, under load. WOT up a fairly steep hill works well.
Sometimes as with my XS400 the idle adjustment screws can only be reached if the fuel tank is removed. You really need a blow up pic of the carbs. Some of the sites that sell parts, have blow up pics.

Bon chance. UK
 

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Ace Tuner
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If I'm looking at the correct exploded view, the fuel mixture screw should be under a "cap" located at the top center of the the carburetor/s venturi and up front close to the intake manifold (carb holder).
If that is where it is located it will be right in the center of the bore for the venturi and the cap that covers it will be flush with the carb body.
The cap has to be drilled in order to remove it so you can get to the fuel mixture screw underneath the cap.

The Suzuki parts diagrams I can find, for 1980 model, does not show the fuel screw or the cap covering it but there has to be a fuel mixture screw for each carburetor.
BTW.
It's not uncommon for something to be missing from the parts list for a Suzuki that's nearly 40 years old...
 

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That is where the screw is on my XS400, and why the fuel tank needs to be removed. I thought it might be the same on the Suzuki.
If you have a plastic orange gas tank with a vent hole. You can drill the hole bigger, to accept a fuel line that is a snug fit. A T section in line if there is more than one feed to the carbs. My XS400 has a single feed, and the XS1100 has two feeds. Two carbs are linked for fuel.

UK
 
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