Air jet covers + gaskets in VB44A/C carbs. What in the world do these do?

[fizzlebottom]

The number of times I've taken my carbs apart for cleaning, I never gave them a second thought. They live under the piston cover. I always unscrewed the kidney-shaped plastic bits and barely-holding-on paper thin gaskets, set aside while I cleaned everything else, then just put them back for reassembly.

But I noticed in the parts fiche diagrams that these came with replacements in original Honda carb rebuild kits. I've never seen them in any aftermarket kits though. Found out that they're called "air jet covers".

So I found some images of those rebuild kits and noticed that the gasket underneath is supposed to be rubber, and a deal thicker than paper. Seems mine have collapsed to the point where they're probably not performing as gaskets rather than soft washers.

The other odd bit I found is that very similarly-designed Keihin CV carbs do not have the gasket; just the black plastic cover.

What is the function of these? I assume they're critically important like just about every other component in the carbs. But if the gasket material isn't sealing anything or restricting airflow, then is it impeding either vacuum operation of the piston or creating a lean condition? Why don't rebuild kits come with replacements?

I'm wondering if the few folks who have had perpetual lean running issues have ever looked at this as a culprit.

Thoughts?

[Volker_P]

I did not have CV carbs on a CB650 so I have no direct statement to this issue.
But I know from the piston carbs that there are e.g. versions with and without air cutoff diaphragms.
All PD carbs have the diaphragm covers but in most carbs there are no air cutoff diaphragms and the corresponding channels are somehow visible but are actually not drilled through.
I could imagine that it could be similar for the CV carbs, i.e. that the "air jets" are visibly present in all carb bodies but may be dummies in some versions. These would require no cover gaskets then.
If this assumption should be true one probably would run into some trouble without the gaskets on carbs where these opening are active.

[kerryb]

I recently rebuilt a set of CV carbs on a goldwing, those kidney shaped covers are rubber, and do seal the air jets. I get my carb parts from Randakks because the parts kits are complete and the highest quality.

[Volker_P]

Thanks for clarification!