HELP IDK what this is--- 1978 GS550 Carb parts and adjustment screw

[prichmon]

20200717_162216.jpg


I found this screw on the carbs. I cross referenced to Bikecliff's website. According the the Mikuni manual for the VM29s it is the shock adjuster. I am also missing a spring or two.

Does anyone know how to adjust this item?
Dow I need 1 or 2 screws?
Do I just call Mikuni?
I don't see them called out on the microfiche.

Any help is appreciated guys.

Thasnks

Rich

[Steve]

The screw is the throttle limiter. Open the slides all the way, they should not block the throat at all, and should not be more than about 1mm above the throat. Turn that screw to adjust that. The spring is just a tensioner to keep the screw from turning on its own.

.

[chuck hahn]

As Steve said. Reason is that if the slides ( bottom edges of them ) open further than 1MM it spoils the action of the venturis. In other words the carbs work like schnit.