Petcock question

[Briansred82]

Hi there all I have a rookie question. I picked up a petcock off Ebay do all units have the main fuel line and a vent tube? I was wondering what the smaller brass outlet is? Only thing I could think of is a vent. Brian

[Rich82GS750TZ]

Not a vent, the smaller nipple is for the vacuum line.

[Briansred82]

Rich does it connect to one of the outboard carbs? I am normally good a t marking the lines but this one got by me. Brian

[rphillips]

Hey Brian, you didn't say what bike you're working on & it's not in your sig. , but on most # 2 carb has the vacuum port

[Rich82GS750TZ]

Brian, we don't know what bike you have.

Carbs are numbered 1,2,3,4 from left to right as you sit on the bike.

To clarify a bit on what rphillips wrote. On the pre-1980 VM carbs, the vacuum port of the petcock goes to a port on the back of Carb body # 3. On 1980+ GSs w/ CV carbs, the vacuum port of the petcock goes to a port on the front of carb body # 2. pics below.


pre-1980 VM Carb hose connections:


1980+ CV Carb hose connections:



It's time to get yourself a manual from BikeCliff's Website, and also to read the Top 10 Newbie Mistakes Thread. Both are linked in my Signature.

[Briansred82]

Thank you for the photos I appreciate 82 1100E

[Rich82GS750TZ]

So CV carbs. Look at the pic of the CV carbs I posted above. Not shown is another bowl vent port between 3 & 4 just like the one between 1& 2.