carb question

first i have never seen petcocks like these which adds to my confusion...I have a service manual for my 1100 which shows all the proper fuel,vac line lay out...except my back does not match it...i removed my carbs last night and have 2 fuel lines and one vac line going up to the diaphragm from the carb body , the 2 vac lines that are suppose to come off the petcocks and go to the diaphragm are not there at all, how was i able to ride the bike with no vac lines going to the petcocks? they were in the RUN postion...i am wondering if i should put new vac lines on or do you think this has been bypassed somehow?

thnx

 

The petcocks on an XJ1100 are not vacuum-operated... The forward outlets are PRIme (3 & 4) and the back ones are "ON" (1 & 2). The vacuum only operates the diaphragm (a single vac line from one of the manifolds), which is only relevant when the petcocks are in the "on" position. When you apply vacuum to the diaphragm, 1&2 flow into 3&4 respectively. Some folks remove the "octopus" all together and cap off the PRI outlets , which is nifty cause then you have more room for some inline filters... Just have to get in the habit of turning the petcocks off after every ride... just in case.

 

The pitcocks on the 1100 are vacuum operated. I would get the pitcock repair kits it comes with the vacuum repair kit and put it back together right.
On postion bypasses the vacuum diaphram to fill the bowls when empty.
Primary is Vacuum operated and is the postion or normal operation.

 

Hey, Hardluck ... you're mixed up about Petcock Operation.

ON = Main Supply of Fuel from Tank switched ON or OFF via Vacuum from Manifolds. Yes Vacuum = Flow /// No Vacuum = Off

PRI = Prime. Fuel Flow is ON and Stays ON at all times. Used to fill Carbs after Drain Screws are removed for lay-up or Carb Work.

RES = ON with Petcock drawing Fuel from Reserve Level below Petcock Screen.

Leaving the Petcock in PRIME places you at risk for flooding-out and getting Gas into the Crankcase.

 

Ok, this diagram should make it more clear... (clickable)


As you can see, vacuum operates the common diaphragm (also, known as the "octopus" or "who in god's name designed this") while the petcocks are just multi-port selector switches, for the lack of a better description.

Image borrowed from XS11.com.

Edit: this diagram is for the 1982 XJ1100 "factory" setup as well as some XS1100 models. Hardlucktx, if your XJ1100 doesn't have this setup, maybe it's been redone by a PO?

 

thnx guys, I will cap the 2 forward vac lines on the petcocks off, the night i brought her home i left the fuel in the on position..the next morning i could see where fuel had been dripping out of the petcock where those vac lines go.

thnx again guys

 

Plus those 1100 Petcocks run a separate Outlet for Reserve.

The Octopus is just a Common Vacuum Shut-off Valve.
That means there's more to troubleshoot.

 

Ok the PO had mine hooked up backwards I didnt have the diagram .marked them when I took the off and put them back that way. I have put them back the right way now.