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One of the Harley riders I work with brought to my attention that it is always best to turn your fuel off when you shut your bike off. I've always done this when I was riding dirt bikes but never thought there was a need for it with a street bike. I can see the reasoning if your bike is gonna sit for a period of time (2 weeks or more).

What do you guys have to say about this?
 

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It has a vacuum actuated petcock that automatically closes when the motor is not running... when it's working properly. i almost never turned mine off.
 

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Knightslugger said:
It has a vacuum actuated petcock that automatically closes when the motor is not running... when it's working properly. i almost never turned mine off.
The vacuum petcock actually works better than I expected. I had my tank off for a good 3 months and never had any fuel leak out (it was sitting on cardboard, so I would have seen any moisture). I was almost certain at least some would leak over that period of time, but mine works REALLY well.
 

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I disabled the vacuum valve on the petcock so I always switch off the manual valve. I just do it as part of the shut down procedure so it is no big deal. I found the vacuum valve to be more trouble than it was worth for a variety of reasons.
 

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dwengi said:
I disabled the vacuum valve on the petcock so I always switch off the manual valve. I just do it as part of the shut down procedure so it is no big deal. I found the vacuum valve to be more trouble than it was worth for a variety of reasons.
um............... ??? Why? It opens when the motor runs, closes when it's off. if your floats ever fail (and they do from time to time) you'll end up with a pool of fuel under your bike and gasoline in the oil...
 

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dragknee said:
dwengi said:
I found the vacuum valve to be more trouble than it was worth for a variety of reasons.
please explain
1. If you use the manual valve the vacuum valve is redundant. I always turn the valve off when I park it so I do not worry about fuel leaking past carb float valves.
2. The action of the manual valve is more robust and positive in my opinion compared with the diaphram actuated vacuum valve. In other words I put more faith in the manual valve to completely shut off the fuel flow than I do the vacuum operated valve.
3. For general troubleshooting I like to be able to open the petcock and see the fuel flow without having to use the mityvac on the vacuum port.
4. A ruptured diaphram or cracked vacuum hose will stop fuel delivery which could be difficult to diagnose and repair on the side of the road.

As long as you are religious in turning the manual valve on/off I see no need for the vacuum valve.
 
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