What is the purpose and setting for the pilot screw (1994 GS500E)

[sladerunner]

I took the carb apart to clean as it will only idle...dies as soon as you give it any gas. They were set approx 3.5 turns from bottom, what is the factory setting for these?

Also, what makes the piston air valves in the carb move up and down as you give it gas?
Mine freely move with your fingers, but they don't seem to move up as you give it gas, however if I carefully raise both at the same time with my fingers while giving it some gas, I can get the engine rpms up.

I notice with the top two covers off that hold these air valves in place there is a vacuum port with an o-ring to seal them off. I don't understand what this vacuum port does as it's just sealed off with the o-ring against the top cover.

Help!

thanks

[Zook]

The pilot screw adjusts the air/fuel mixture. Most set them at 2-2.5 turns out and adjust from there.

The carb slides are operated by engine vacuum. If they are not working, take the tops of the carbs off and look for rips in the diaphragms.

You bike will run like crap without the airbox or filters. Way, way too lean. You crack the throttle and it stumbles. That may be what you are experiencing.

[sladerunner]

re: what is purpose pilot screw

I put the air box on and filter and no difference.

I took the carbs off and set the pilot screws to 2.5 turns I also looked for rips in the slide rubber deals..they appear to be in perfect condition.

Still no difference.

Is that vacuum port supposed to opperate these slides? It just doesn't look like it can, as it's sealed off by the o-ring and the top cover.

It's like i'm missing a vital piece of info here...any other suggestions?

[Steve]

The vacuum that lifts the slides comes through holes in the bottom of the slides. You have to have the airbox installed, with a filter in it for them to operate properly. Without a load on the engine, you may never see the slides go up.

Not sure what you are describing with the o-ring and such, can you post a picture?

Are these the infamous 2-barrel carbs? They use the same principle, but different parts.

.