85 GS550 Idle Jets

[Anonymous]

I posted this question (along with some others) under the heading Carb Rebuild, but I think I asked too many questions to get a reply. So, at the risk of being rude, I'm reposting just the information about the idle jets.

I have an '85 GS550L with the weird dual-throat carbs. An exploded diagram may be found here.

http://67.15.65.225/spst/1985%20GS550L/06.htm

How does one remove the caps protecting the idle screw? Do you then just throw the plug away, or re-install it after servicing?

Assuming my idle screws are too gummed up to figure out where they are set, does anyone know a baseline setting for this carb?

Once I've set the baseline, how do I adjust from there?

Thanks,

Rob

[Jethro]

I read that post before, and didn't reply because I don't have experience with those carbs. However, by the diagram you posted, they look like regular CV carbs with the velocity diaphragm on the slide and everything. If that is the case then:

1. The plugs don't cover an idle screw. Those are mixture screws for the pilot circut, they only adjust the ratio of fuel to air for the pilot circuit. It only affects idle because of the mixture. Just clarifying so you don't get confused and expect to set your idle with them.

2. If they are like the reg. CV carbs on the bigger 4 bangers, then the plug can be removed as follows- drill a small hole right through the aluminum plug. Go slow and be prepared to pull back the instant you break through becasue the mixture screws are just beneath the plugs. Then drive a screw into the plug and pull out with some pliers. Throw the plug away, the factory only put them in becasue you shouldn't have to mess with them ever unless you do some modifications- again, it's not an idle screw, only a preset mixture screw.

3. Suzuki never published a setting for these screws becasue after tuning using an emissions probe, they shouldn't ever need to be changed. The general concensous for the big 4 cyl bikes is 2-3 turns out, but again, that depends on engine mods, exhaust, etc.

[Jethro]

BTW, your idle is set by part number 66 in that schematic.

[Jethro]

On a 3rd look of that schematic, I'm not sure if the plugs are in any way the same as the carbs I am used to, so maybe disregard everything in my post.

Your welcome!

[Anonymous]

It is very possible that I've used the wrong words here or there...

Idle speed is indeed adjusted by #66. But that does not impact mixture in any way.

The plugs I am talking about aren't exploded in that exploded diagram, so I dont' really (yet) know what is under them. But they are the round things with the dot (in a horizontal plane) located between where parts #41 and #33 go in.

And I think there is some sort of needle valve screw under there for adjusting the mixture in some way...

If there is an o-ring under there, I will be annoyed, but oh well...

I also think the carbs are synched by adjusting #22. Aside from the float, I don't think there are any other adjustments that can be made to this carb. Am I right?

Rob

[Jethro]

Correct. #22 definitely adjusts the synch. The only other real adjustment would probably be with the float height. This can seriously affect rich or lean running conditions.