Does a 1980 honda cb750 ss have a vacum petcock?

Question

oh and this may be the dumb question but what is the tube coming out of the carbs on the top....... other than the fuel nipple.... im pretty shure it goes to somthing but i don't know what?

Answer 1

No, the 1980 CB750 petcock was a manual only device.  On -OFF - RESERVE.

Although Yamaha had introduced the vacuum actuated petcocks on their new bikes, the Honda did not use this technology back in 1980.

There are 4 vacuum ports and 3 adjusters.  Carb sync sticks usually have the adapters to sync.  If memory serves, #2 cylinder can't be adjusted.  

here's a great site, plenty for 750/900/1100 owners

http://www.cb1100f.net/

I think the tube is also the throttle sleve, but  a picture might get you even more help.

Answer 2

It might be the vent for the float bowls.  With no way for the air inside the bowls to escape, fuel can't flow in, hence the vent.

Answer 3

If you mean straight off the top, that's the throttle cable.