Idle Mixture Screw

[dtkid]

Has anyone ever paid attention to this?

When screwing the idle-mixture screws down completely(obviously after drilling out &/or removing the factory-installed "cap") .......does the tip of the screw stick out of the hole in the top-side of the carb?

I just noticed that before I actually screwed the idle-screw down completely the tip of the idle screw was pertruding out the port; I could run my finger along the top surface of the inside of the carb throat and feel the point of the screw.

Should the tip pertrude out the air port when firmly seated? Are we to consider the point at which the tip pertrudes to be "dead-bottom"? I've always thought that "dead-bottom" on those mixture-screws to be a little inconsistent. CAn anyone advise?

[tkent02]

Yes it sticks out just enough to feel it, see it.
It is hard to get a bottomed feeling in these, if you put it in very hard the tip sticks and breaks off, very hard to remove without ruining the port it's in. If you take the screw out and clean it, clean the threaded hole of all remnants of the paint that was there to prevent it moving after it left the factory, and put a drop of oil on the threads, you can feel when it bottoms. It never really hits a stop, just gets a little harder to turn in, stop there. Helps to have the carbs off so you can see the tip as it bottoms out.

[dtkid]

Do you have a feel for this?

Once the screws have "bottomed" and the 1.5 turns out have been completed....can you still feel the tip pertruding?

[tkent02]

No, I just went out to my 750's VM carbs and stuck my finger in, can't feel the tip.
The tips disappear from view as soon as the screws are turned, less than 1/4 turn or so from bottomed they are gone from sight.

[Billyboy]

Unless it's broken.

[tkent02]

Unless it's broken.

Good point.

[Colin Green]

Prolly a silly question, but are the rubber O rings on the jets?

[Billyboy]

Yes. The needle jet that the main screws into, the pilot, I think the fuel adj screw...

[Suzuki_Don]

No, I just went out to my 750's VM carbs and stuck my finger in, can't feel the tip.
The tips disappear from view as soon as the screws are turned, less than 1/4 turn or so from bottomed they are gone from sight.

Is he talking about VMs or CVs. Both the '80 and '81 GS750L used CV carbs so info on the VM might not be applicable.