Fuel line help

[scooterst]

So a local mechanic told me to pop off my tank and hook a fuel line direct from the gas can to see if the carbs are getting enough fuel. It looked like it was trickling out of my tank and any time I opened the throttle it dies.  That's the background, here's my issue where do I connect the fuel line on the carbs or is it in the right place already?  On Carb #2(shown below) I found the fuel line and another fuel line hose that was cut about 1inch tall(removed the cut hose), what is that? Which place is the right spot for my fuel line?  Its a 1978 CB750 with Keihin carbs, F3 I believe. I'm new and may be wrong on info, any direction and help is much appreciated on this.  

Thanks,
Scooter

[Tech78]

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[scooterst]

Ah okay, awesome, thank you.  I will add that and see if it will run.  I looked through 2 manuals and a few online sites with the exploded view OEM parts and could never find anything that talked about the vent or showed a close-up/detailed view of that carb and where the line connected, so thank you again!

[7883750S]

I have been stumped by the vent also...Should the vacuum line be plugged?

[mike]

what was the answer? i have the same problem

[Re-run]

It is just a vent line. There is normally a hose that would sit on top of the air box. I would still put a hose on it, then tie it to something and put some sort of filter on it.

[sgtslag]

I read on another CB750 forum that individual filters will screw up the air flow/fuel-air mixture on CV carbs.  According to the folks on that site, you have to install different carbs to use the separate air filters -- you will never get the CV carbs to work with individual filters.  Sorry if your carbs are correct for four air filters, don't know that much about it, really.  Here is a link to the other forum's discussion on this topic:

http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&t=5048

Cheers!