Author Topic: Petcock question  (Read 700 times)

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Offline excerpt

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Petcock question
« on: March 22, 2010, 09:23:00 AM »
1974 CB750K

After installing clear fuel lines, I noticed that one of the nozzles flows freely, but one doesn't dispense much fuel.
I took the petcock off and cleaned it thouroughly (didn't seem too dirty), and after installing it, it still doesn't flow out of one of the nozzles on the bottom.

I blew carb cleaner, and then air through it when I had it disassembled, and it seemed to pass through both of them, but I barely get a few drips out of one of the nozzles after reinstalling it.

What to do to?

Edit to add: If I put my finger over one nozzle, the other nozzle flows freely. That leads me to believe that it isn't blocked by anything. Is it supposed to do this?

The only way I can think that this would work, is if the first fuel line gets full, and then the resulting backup causes the other nozzle to begin flowing.

Is this how it works? Do I need to just put it back on the bike, and let it do it's thing? I have GOT to get these carbs synced. The bike needs to be running, as I am moving tomorrow.
« Last Edit: March 22, 2010, 10:02:37 AM by excerpt »

Offline Laminar

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Re: Petcock question
« Reply #1 on: March 22, 2010, 11:23:15 AM »
Do all four carbs fill up as they're supposed to? The only time a significant amount of fuel is going to flow through the lines is when the tank is filling empty carb bowls. Under most conditions, there will be a very slow flow to maintain fuel level in the carbs.

If you get the bike running and all four bowls are filling up properly, I wouldn't worry about it.

Offline Nikkisixx

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Re: Petcock question
« Reply #2 on: March 22, 2010, 11:38:10 AM »

If you get the bike running and all four bowls are filling up properly, I wouldn't worry about it.

+1  It is my understanding that fuel travels over the first tube then then makes it to the second.  Once the first tube is full, the second one will fill and they will flow equally.  Until that happens the first "steals" all the flow.  

edit: so yes excerpt, I support your theory  :)
« Last Edit: March 22, 2010, 11:40:11 AM by Nikkisix »
It is a proven fact that modifying a SOHC Honda in any way will bring on the apocalypse.

Offline Alan F.

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Re: Petcock question
« Reply #3 on: March 22, 2010, 08:41:33 PM »
You're good, put it back on and enjoy.