carb stuff

[Superfly]

Hey all, these carbs are on ebay, and I have a question about the white thing sticking up in the picture, I have 2 sets of carbs, one has this and one does not, what is it and what does it do?

[h2olawyer]

That is an air filter assembly that was included as part of the airbox flapper upgrade in 1982.  I'm not exactly sure what section of the carburetion or vacuum system it works on.  I haven't bothered to check when I've had mine apart.  The one you have without the filter is likely an unmodified '82.  Rick_G, Lucky or one of the other carb gurus likely understands the function of this part.

It fits into that black disc shaped part on the front carb & clips into the tynes.  I think there is supposed to be an O-ring that helps hold it in place as well.

Hope this answers 1/2 of your question.

H2O

[Lucky]

The one without the filter should not have the fitting for it either, if it does it's just missing.

you will also notice that on the modified carb, looking at the top you will see 3 holes in the airhorn, these are air bleeds, one has a brass tube in it, one has the pilot air jet and one either has a hole (on the rear) or is blocked (on the front).

on the unmodified airhorn there are no fittings for the airbox, round filter and the bleed passage is open.

Yamaha changed the design of the front air bleed to suck air thru this little round filter instead of the big air filter. I believe it was to help regulate the amount of a/f mixture to the front carb  that's the best way i can explane it without taking up 2 pages...
--Lucky

[Superfly]

Lucky, Is it nesessary, It looks like my carbs that do not have that air filter piece on it, has the fitting for it.  Should I take the filter from the other carbs and put it on the carbs that I am using?

[Lucky]

Yes put it on, you have nothing to lose by installing the filter.  it's unlikely that you'll suck anything in that tiny fitting, but it does go directly into the carbs chambers.  look at it this way, if the pieces cost Yamaha a dollar to make, and they added them to 100,000. bikes, that's a lot of $$ they could have saved....

[Superfly]

Thanks Lucky, When you are right, you are right...

[Lucky]

And when i'm left...well, I have to walk.... ;D