Suspicious vacuum line

[Padre4art]

Hey Guys - and Gals - today I discovered a vacuum line connected to the number 4 carb inlet vacuum port (right hand carburetor) on my 1979 XS11F (standard). The vacuum line goes down towards the gearbox but isn't hooked up to anything. It's just open to the atmosphere!

My impression was the outer two carb inlet vacuum ports should be capped off? Huh?

Thanks!

[BA80]

Goes to the right petcock vacuum valve..

[Padre4art]

The petcock vac lines are already hooked to the inner two carb boots. This is a third vac line connected to the outer carb boot on one end and nothing on the other end. Weird!

[bikerphil]

Get rid of the line and cap the # 4 port.

[Ken Talbot]

Is the line for the vacuum advance mechanism still connected to the nipple on the body of carb #2?

[Padre4art]

The petcock vac lines are hooked up to the two inner carb boots. The suspicious line goes from the right outer carb boot to nothing . . . Open to atmosphere. I am assuming the vac ports on the two outer carb boots are supposed to be capped off?

[kboehringer]

Buy the OEM port caps.

supposed to be capped off?

Yes. Cap it off as previously indicated by BikerPhil.

NOTE: I have found that the cheapo rubber vacuum caps found at auto parts stores like Autozone, Advance Auto, etc. work just fine for a short period of time. But they will fail and leak relatively quickly. This is especially true if you pull them off/on a couple times to tune/sync the carbs etc.

The OEM Yamaha port caps are much thicker and better designed for that hot area of the bike. The OEM caps are a couple bucks each but well worth it and still readily available from Parzilla.com and other similar retailers.

KURT

[skids]

There is a breather hose that goes from the transmission (?) to the plate where the rear mounting of the gas tank is. It is open to the atmosphere. Just so you know. It is open on the upper end.

[DiverRay]

There is a breather hose that goes from the transmission (?) to the plate where the rear mounting of the gas tank is.

It's actually from the middle drive, and it NEEDS to go up to the tank. My '79 had it going down when I first got it, and it sucked water into the middle drive and spewed gunk all over the bike on a "quick" ride down to Solvang.
As stated: #1&4 should be capped, #2&3 go to the petcocks, and vacuum line from #2 CARB BODY goes to the vacuum advance/retard under the left crank cover.
And yes, use GOOD plugs, but change them about every ten years, as they WILL get hard and leak.

[BA80]

It's actually from the middle drive, and it NEEDS to go up to the tank. My '79 had it going down when I first got it, and it sucked water into the middle drive and spewed gunk all over the bike on a "quick" ride down to Solvang.
As stated: #1&4 should be capped, #2&3 go to the petcocks, and vacuum line from #2 CARB BODY goes to the vacuum advance/retard under the left crank cover.
And yes, use GOOD plugs, but change them about every ten years, as they WILL get hard and leak.

trbig had that happen coming back from XS Southeast once. He had the middle drive vented under the bike. Sucked up water and turned the gear oil to milk.