Author Topic: Fuel Tank Fuel Valve  (Read 2791 times)

Flyer23

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Fuel Tank Fuel Valve
« on: April 04, 2022, 09:36:23 PM »
Good evening. Is there a mechanical fuel shut off valve that will fit the fuel tank so I can get rid of the vacuum valve? I think it's sticking and under load the carb is running out of fuel at high RPM. It then bogs down and stalls. It will restart after a few minutes but it seems to me there is no fuel as when you crack the throttle it just bogs down when trying to ride. Yet several times it has seems ok and that's what makes me think that valve is sticking because the NEW fuel filter looks like there is only a small amount of fuel in it. I would think if fuel was flowing properly and the carb was not running out of fuel the filter would look pretty full, no ? Fuel filter is new and carb is also new. Thank in advance,

CROSSBOLT

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Re: Fuel Tank Fuel Valve
« Reply #1 on: April 04, 2022, 09:46:59 PM »
Vacuum valve sticking produces the same symptoms....
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

JJJoseph

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Re: Fuel Tank Fuel Valve
« Reply #2 on: April 06, 2022, 09:19:37 AM »
It depends on your machine.  Some have steel tanks with threaded couplings, but for the last 20 years most have nylon fuel tanks with press-fit couplers with o-rings.  These are harder to modify like you're describing because you can't thread in a new valve.

Flyer23

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Re: Fuel Tank Fuel Valve
« Reply #3 on: April 06, 2022, 03:36:12 PM »
It depends on your machine.  Some have steel tanks with threaded couplings, but for the last 20 years most have nylon fuel tanks with press-fit couplers with o-rings.  These are harder to modify like you're describing because you can't thread in a new valve.

Machine is a 2005 Kymco Super 9

eamartin

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Re: Fuel Tank Fuel Valve
« Reply #4 on: April 07, 2022, 01:29:19 PM »
I have had the occasional vacuum fuel valve failure.  In the case of an Agility I was able to match up an economical non-OEM vacuum style replacement.  I would first disconnect the fuel line from the carb and put a draw (like using a straw) on the vacuum line to test the flow of fuel through the fuel valve into a jar.  A fresh new vacuum hose is also an inexpensive place to start - and not a bad idea on an older scooter.       

JJJoseph

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Re: Fuel Tank Fuel Valve
« Reply #5 on: April 08, 2022, 07:01:36 AM »
Machine is a 2005 Kymco Super 9
I didn't mean to suggest that I know every Kymco fuel system, so I don't know what a 19-yr old Super 9 has in the way of a fuel tank.

Flyer23

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Re: Fuel Tank Fuel Valve
« Reply #6 on: May 01, 2022, 09:37:40 PM »
Does anyone know where I might find a manual fuel tank valve? I can't find anything.

CROSSBOLT

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Re: Fuel Tank Fuel Valve
« Reply #7 on: May 01, 2022, 10:04:05 PM »
Does anyone know where I might find a manual fuel tank valve? I can't find anything.
Hardware stores like Ace, Lowe's, Home Despot have brass petcocks that could be adapted. Motorcycle salvage yards probably have fuel tanks with manual valves.
Are you sure it is not the vacuum operated fuel tank vent valve that is sticking? It will produce the same symptoms.
Karl

Three motorcycles 1960-1977 (restored a 1955 BSA)
Agility 50
Yager 200i
Downtown 300i
Navy tech, Ships Engineer, pilot and aircraft mechanic

Flyer23

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Re: Fuel Tank Fuel Valve
« Reply #8 on: May 11, 2022, 05:16:10 PM »
Hardware stores like Ace, Lowe's, Home Despot have brass petcocks that could be adapted. Motorcycle salvage yards probably have fuel tanks with manual valves.
Are you sure it is not the vacuum operated fuel tank vent valve that is sticking? It will produce the same symptoms.
Ah yes I was able to remove a vacuum valve from the tank, but it looked like it went to the carb. That's the valve I'm try to get rid of and just use a manual valve to leave open all the time since you can't get to it easy. Then put a second petcock after the fuel filter so I can shut the fuel off and on

2StrokeVapors

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Re: Fuel Tank Fuel Valve
« Reply #9 on: July 26, 2022, 02:19:21 AM »
Ever find a manual shut off that fit? Was thinking of doing the thing in my current build. Not having the same issue but would rather have no vacuum to worry about.

Flyer23

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Re: Fuel Tank Fuel Valve
« Reply #10 on: August 01, 2022, 07:40:18 PM »
Ever find a manual shut off that fit? Was thinking of doing the thing in my current build. Not having the same issue but would rather have no vacuum to worry about.

Racingplanetusa.com

fuel tap 15mm vacuum to manual conversion for Aprilia, Kymco, Piaggio, Rieju

2StrokeVapors

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Re: Fuel Tank Fuel Valve
« Reply #11 on: August 04, 2022, 06:19:29 PM »
Racingplanetusa.com

fuel tap 15mm vacuum to manual conversion for Aprilia, Kymco, Piaggio, Rieju

Sweet! I will have to grab one and try it out.


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