Topic: CB350F fuel lines question

[goldwing55706]

Recently I purchased a 1973 CB350F project.  It came without carbs so I purchased a set on e-bay and took them apart and cleaned them.
There are 3 "fuel lines" - I believe that the short one goes to the petcock.  Are the other two vent lines?  Where to they connect if anywhere?
To get the center two airbox hoses onto the carbs, I took all of the bolts out of the air cleaner/battery box holder, unbolted the electrics, and moved the battery box/air cleaner housing to the side allowing me to get my fingers inside and push the center two airbox hoses onto the carbs.
Thanks for you help,
Jon

[flybox1]

those 2 vent lines should hang down and "drain" just in front of your rear tire.
You should be able to reach your hand inside the airbox once the filter is removed, and press #2/3 onto the carbs.
if you have big hands, stick the butt-end of a hammer in there and press gently.
should wiggle on just fine.

[Lars]

Those two vents on the carb provides the correct atmospheric pressure in the carbs float bowl. The two rubber hoses is not neccessary, but they prevent any fuel spilling on the engine when the bike is tiltet. They also prevent any dirt to stuck the vents.

The atmospheric pressure inside the carb bore venturi is lower than outside when the engine is running. Thus the fuel and air mixture is sucked up into the carb bore and into the combustion chamber. Getting the correct atmospheric pressure in the float bowls, this will in addition to the vaccum in the bore press the fuel through the valves and into the bore. Without the vents, you would build up a vaccum inside the float bowls that would equalise the low pressure side in the carb bore venturi resulting no fuel/air mixture to the engine.

[goldwing55706]

Thanks Flybox 1 and Lars.
The ability to ask questions in tech forums and receive answers within a few hours is awesome!
Jon