The International CBX Owners Association

Hello! There is one vacuum hose from the auto valve (the valve between fuel tank and carbs) going to the #3 carb. The one on the left has no hose at the moment. Where is it supposed to go? To the #4 carb?

Somebody will be along with the right info soon but I think that is just a vent hose

That is just a vent, can be left as is, however with the addition of a foot of tubing, you can use it to actuate the autovalve and fill the bowls by blowing into it enough to open the diaphragm.

Many thanks. I saw some strings suggesting removing this auto valve. Is there a benefit to having this or not?

Darrell wrote: Thu Mar 20, 2025 11:35 pm Many thanks. I saw some strings suggesting removing this auto valve. Is there a benefit to having this or not?

I took those off both my ‘80 and my ‘82, and both bikes were much easier to live with - the bowls gravity fill without having to tax your battery and starter gulping air to open the diaphragm. You have to be disciplined about shutting the petcock every time, but if that’s no problem, I say remove it, install a brass T in its place and sail on.

Got it! Many thanks!

FWIW, from the factory, Honda supplied a maybe 30 inch hose to route from the vent outlet, over the right top of the central air chamber, follow the clutch cable and oil line, then finding it's way to the cluster of hose drain outlets clamped in the bracket on the right center stand pivot clamp. As Nils said, you can just have it tucked behind the frame rail, just above the right foot plate, accessible easily to blow into to fill the carb bowls.

Dave