Vacuum fuel petcock still passing fuel when engine is off

[Anders74]

Suzuki gsx750e 1980

I repaired the Fuel petcock and first when i tested it when it was open (just with water) the oring worked fine and when we applied vacuum it goes down.

Then hocked the tank to the bike and started it. After i stop engine, it still comes petrol all the time. It same Peackock typ like that in the middle.

Also i dont know exactly how it works and how do activate the PRI or just ON..Is this fixeble?

Thanks!

 

 

 

[Suzukian]

I'd put a simple in line On/Off fuel switch.  Makes life much easier.

[Anders74]

5 hours ago, Suzukian said:

I'd put a simple in line On/Off fuel switch.  Makes life much easier.

And where can you find that?? = ) 50mm CC? Its really hard to find...

[TonyGee]

they are a problem tap to repair as their is a secondary vacuum in the base of the tap thats sealed, best thing you can do is bin it and buy a new one, had to do that with mine. 

[Suzukian]

I'm sorry, being in the U.S. they have that petcock listed on Amazon new for $20 bucks.  I don't how that works out as far as ordering, but here's the link where I found one based on the info you gave on your motorcycle.  I hope it can help you.  What I mean about the in line On/Off valve is the kind you use on tractors, you just keep the stock unit one, tap into the line going to the carbs, then mount a manual On/Off valve.  The ones they sell here comes in stepped hose sizes, you just cut off what you don't need.  With this kind of set up, you must always remember to shut off your gas though. Also, there's the name difference on bikes sold in the U.S.  which really messes things up.

 

Link =  https://www.amazon.com/Petcock-Suzuki-GS750E-GS1000G-44300-45011/dp/B07D4JP9Y8

 

 

 

 

Edited September 27, 2025 by Suzukian

[Anders74]

12 hours ago, TonyGee said:

they are a problem tap to repair as their is a secondary vacuum in the base of the tap thats sealed, best thing you can do is bin it and buy a new one, had to do that with mine. 

Thanks for answer! = )

[Anders74]

6 hours ago, Suzukian said:

I'm sorry, being in the U.S. they have that petcock listed on Amazon new for $20 bucks.  I don't how that works out as far as ordering, but here's the link where I found one based on the info you gave on your motorcycle.  I hope it can help you.  What I mean about the in line On/Off valve is the kind you use on tractors, you just keep the stock unit one, tap into the line going to the carbs, then mount a manual On/Off valve.  The ones they sell here comes in stepped hose sizes, you just cut off what you don't need.  With this kind of set up, you must always remember to shut off your gas though. Also, there's the name difference on bikes sold in the U.S.  which really messes things up.

 

Link =  https://www.amazon.com/Petcock-Suzuki-GS750E-GS1000G-44300-45011/dp/B07D4JP9Y8

 

 

 

 

Thanks! = )

[Anders74]

6 hours ago, Suzukian said:

I'm sorry, being in the U.S. they have that petcock listed on Amazon new for $20 bucks.  I don't how that works out as far as ordering, but here's the link where I found one based on the info you gave on your motorcycle.  I hope it can help you.  What I mean about the in line On/Off valve is the kind you use on tractors, you just keep the stock unit one, tap into the line going to the carbs, then mount a manual On/Off valve.  The ones they sell here comes in stepped hose sizes, you just cut off what you don't need.  With this kind of set up, you must always remember to shut off your gas though. Also, there's the name difference on bikes sold in the U.S.  which really messes things up.

 

Link =  https://www.amazon.com/Petcock-Suzuki-GS750E-GS1000G-44300-45011/dp/B07D4JP9Y8

 

 

 

 

Doesnt look like 50mm CC. Do you know? Also cant buy it. Im from Sweden! Do you know any other place online?

[Mark0]

I picked mine up from Eblag i believe it's from a kawasaki z650. It was from legend motorcycles. They may ship to you but you would need to check. I haven't fitted mine yet but if you want me to double check hole distances i can. My bike is an american import though so maybe different. To be fair the seller did tell me which one to get so they may have info for you based on your model etc. 

[Suzukian]

19 hours ago, Anders74 said:

Doesnt look like 50mm CC. Do you know? Also cant buy it. Im from Sweden! Do you know any other place online?

Wisconsin Motorcycle Salvage These guys have really taken care of me on parts.  They are bikers and like what they are doing.

 

Link =  https://www.Eblag.com/str/Wisconsin-Cycle-Salvage-Inc

Edited September 28, 2025 by Suzukian