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So I need a gallon of gas from my KLR ; I take the fuel hose from the petcock place it to ON and no fuel comes out; I then place it on RES and still nothing drains. Ok maybe the fuel lid need be open , I do and still I can not get any fuel to drain. What is going on?
 

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its vacuum operated, fuel wont flow without the engine cranking. Might be better to siphon it out of the filler :)
 

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+ 1!

Break the fuel line, start the engine, and fuel will flow as manifold vacuum is developed.

Carb runs dry before you've achieved the amount of fuel you want? Reconnect fuel line, crank engine 'til carb float bowl fills, repeat!
 

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So I need a gallon of gas from my KLR ; I take the fuel hose from the petcock place it to ON and no fuel comes out; I then place it on RES and still nothing drains. Ok maybe the fuel lid need be open , I do and still I can not get any fuel to drain. What is going on?
A little more information for you. On the back side of the petcock there is another tube that goes over to the end of the carburetor that the engine sucks on to get its air and gas mixture whenever it is turning over. Since the engine sucks on that end the tube has a vacuum in it. There is a little vacuum powered valve inside the petcock down stream from the ON-OFF-RESERVE hand valve and when the engine is turning over the vacuum in the line opens the valve and gas can flow from either the ON or RESERVE side of the petcock.

The idea is that any time the engine is not running or being started the gas is shut off and will not overflow out of the carburetor. You would like this feature if you had just crashed and your leg was stuck under the bike and gas was overflowing the carburetor onto some sparking wires.

If you need to get gas from the tank you can siphon it or you can pull the vacuum line from the back of the petcock and connect a separate line to the back of the petcock and suck on that line to make a vacuum. No gas will flow down the vacuum line, but I like to use a clear line for siphoning or sucking on the petcock so I can see anything head toward my mouth.
 

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If you need to get gas from the tank you can siphon it or you can pull the vacuum line from the back of the petcock and connect a separate line to the back of the petcock and suck on that line to make a vacuum.
Or, see Post # 3 above.

Merely cranking the engine develops sufficient vacuum to open the petcock; running the engine certainly does.
 

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Or, see Post # 3 above.

Merely cranking the engine develops sufficient vacuum to open the petcock; running the engine certainly does.
Yes it does. For me it depends on how much gas I want to drain from the tank and how much I want to run the starter go get it. The engine will idle long enough on the gas in the float bowl to get quite a bit of gas. If I want to drain six gallons, I might use a different method.

My post above was more to give Twinblown an idea of how the vacuum operated petcock works than about how to get gas out.
 

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If I want to drain six gallons, I might use a different method.
Makes sense.

The OP mentioned, "a [one] gallon," in the IP.

Your explanation of the vacuum-actuated petcock operation appears very clear and valid; helpful I'm sure to twinblown, the OP.

BTW; welcome to the forum, GoMotor! :)
 

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Well, thanks to all the members that replied to my question; I now understand the workings and the reason why I got no fuel to drain. In the future I'll be using a clear hose to syphon any gas I need through the fuel lid. Man they don't make them like they use to..lol
 

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Makes sense.

The OP mentioned, "a [one] gallon," in the IP.

Your explanation of the vacuum-actuated petcock operation appears very clear and valid; helpful I'm sure to twinblown, the OP.

BTW; welcome to the forum, GoMotor! :)
I went back reread the original post. You are right he only wanted a (one) gallon and my suggestions should be ignored. The best way is to run the engine or the starter as previously suggested.
 

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Well, thanks to all the members that replied to my question; I now understand the workings and the reason why I got no fuel to drain. In the future I'll be using a clear hose to syphon any gas I need through the fuel lid. Man they don't make them like they use to..lol
Syphon hose will come in handy if you're riding with KTM's... Lol! :LaughHard:
 

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Don't Suck!

Do it old school. Grab a length of tubing, shove it in the gas tank, start sucking. Problem solved.:64a:
Gasoline tastes terrible (I speak from experience).
Insert a tube into the filler port, use a cloth held with your hand to seal around the tube. Blow (don't suck) into the tube which pressuries the tank and starts the fuel flow. Gravity does the rest.:Tongue2:
 

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Gasoline tastes terrible (I speak from experience).
Insert a tube into the filler port, use a cloth held with your hand to seal around the tube. Blow (don't suck) into the tube which pressuries the tank and starts the fuel flow. Gravity does the rest.:Tongue2:
Won't work or isn't needed.
 

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I was in a hurry and made too short a reply.
On a bike with a vacuum operated petcock just blowing in the tank will not work to get gas to flow through the petcock. If you suck on the vacuum line to open the petcock the fuel will drain out by gravity and blowing into the tank is not needed.
 

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I was in a hurry and made too short a reply.
On a bike with a vacuum operated petcock just blowing in the tank will not work to get gas to flow through the petcock. If you suck on the vacuum line to open the petcock the fuel will drain out by gravity and blowing into the tank is not needed.
Sorry, I didn't make myself clear on my first response.
I wasn't suggesting that the fuel could be blown through the petcock.
Pressurizing the tank (with the siphon hose in the fuel) will "push" the fuel through the siphon tube just as a vacuum (sucking) will "pull" the fuel through.
:t1204:
 

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Sorry, I didn't make myself clear on my first response.
I wasn't suggesting that the fuel could be blown through the petcock.
Pressurizing the tank (with the siphon hose in the fuel) will "push" the fuel through the siphon tube just as a vacuum (sucking) will "pull" the fuel through.
:t1204:
Aha! Two tubes! That would work. Your approach has more finesse than mine.

To avoid gas in the mouth, I just use a clear tube so I can see where the gas is. When there is enough gas in the line for the siphon to work, I remove it from my mouth and lower it to the catch bucket.
 
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