Petcock with off position?

[MrZig]

Is there any petcock with a manual "off" positon that will work with a 78 GS400 tank?

Mine is leaking even when it's in the "ON" position so I figure I would see if there is any petcock with a manual 'off' selector so I don't have to run into the problem again. How long do OEM petcocks last, if I buy a new one?

Also why is there a problem of fuel leaking into the crankcase if its always 'on' with a broken vacuum actuator?

[duaneage]

Well if you disconnect the vacuum line (and plug it so there is not a leak on the cylinder) you have a manual petcock by design. Just turn to PRI when you need fuel.

[hampshirehog]

The original taps will last......31 years. Sorry, just guessing yours is the orginal fitment but they do last a long, long time.

Other taps that'll fit with an on position? In the UK the I'm pretty sure that a TS250 will fit but couldn't swear on it - might be too tall - and the US could be different anyway.

The problem with fuel leaking in to the crankcase is that the crankcase fills up with fuel, you spin the motor over and get a hydraulic lock and bend and bust something.

[MrZig]

The original taps will last......31 years. Sorry, just guessing yours is the orginal fitment but they do last a long, long time.

Other taps that'll fit with an on position? In the UK the I'm pretty sure that a TS250 will fit but couldn't swear on it - might be too tall - and the US could be different anyway.

The problem with fuel leaking in to the crankcase is that the crankcase fills up with fuel, you spin the motor over and get a hydraulic lock and bend and bust something.

Ok I might just buy a new one then. I was wondering why the crankcase fills up with gas, though. My carbs (from a gsx400) have a drainage hose (which works because gas came out of it when the bike was on its side) - would that prevemt oil contamination?

Edit: Scratch that, a new one would be $100. I can't pay that. Gonna have to keep it as it is I spose.

[duaneage]

two ways for this to happen.

A float in a carb gets stuck and the gas runs up and into the engine.

The vacuum diaphram on the petcock breaks and gas finds it's way in through the vacuum line. Not as likely as a stuck float.

These carbs will flood if the bike is on the side stand and the fuel is set to PRI.

[MrZig]

two ways for this to happen.

A float in a carb gets stuck and the gas runs up and into the engine.

The vacuum diaphram on the petcock breaks and gas finds it's way in through the vacuum line. Not as likely as a stuck float.

These carbs will flood if the bike is on the side stand and the fuel is set to PRI.

But would the carb drainage hose prevent fuel from entering the crankcase if the floats stuck?

[tkent02]

Ok I might just buy a new one then. I was wondering why the crankcase fills up with gas, though. My carbs (from a gsx400) have a drainage hose (which works because gas came out of it when the bike was on its side) - would that prevemt oil contamination?

Edit: Scratch that, a new one would be $100. I can't pay that. Gonna have to keep it as it is I spose.

1979 and older had Mikuni VM carbs, which have a float bowl overflow. If the fuel keeps flowing due to bad petcock and bad float valves in the carbs, the fuel goes harmlessly overboard under the bike. 1980 and newer had CV carbs, no overflow due to EPA idiocy.
When they overflow, the fuel goes into the carb through the jets, flows into the airbox and into the engine, ends up being added to the oil in the crankcase in large quantities.
Can cause problems due to diluted oil, perhaps even cause the dreaded hydrolocking we have heard rumors of.

[MrZig]

1979 and older had Mikuni VM carbs, which have a float bowl overflow. If the fuel keeps flowing due to bad petcock and bad float valves in the carbs, the fuel goes harmlessly overboard under the bike. 1980 and newer had CV carbs, no overflow due to EPA idiocy.
When they overflow, the fuel goes into the carb through the jets, flows into the airbox and into the engine, ends up being added to the oil in the crankcase in large quantities.
Can cause problems due to diluted oil, perhaps even cause the dreaded hydrolocking we have heard rumors of.

Is EPA America only? I'm in Canada and my GSX400 engine defintely has a working overflow hose.

[tkent02]

Is EPA America only? I'm in Canada and my GSX400 engine defintely has a working overflow hose.

YES, unfortunately.

[MrZig]

Okay so since my fuel petcock is stuck open and I have an overflow hose, I shouldn't be in any danger of blowing the engine. Might have the odd gas leak though. Correct?

I would still like an On/Res/Off petcock. Simpler and wouldn't cause problems.

[C.V.]

perhaps even cause the dreaded hydrolocking we have heard rumors of.

Not to hijack, but does anyone know someone who has actually hydrolocked an engine this way? The only hydro lock i ever witnessed was a fool on an HD in Phoenix try to ride through a deep (too deep!)puddle...sucked a nice gulp of water through his pretty S&S aircleaner and EEEEERRP!

[tkent02]

Not to hijack, but does anyone know someone who has actually hydrolocked an engine this way? The only hydro lock i ever witnessed was a fool on an HD in Phoenix try to ride through a deep (too deep!)puddle...sucked a nice gulp of water through his pretty S&S aircleaner and EEEEERRP!

Was it a true hydro lock or was it seizing due to suddenly cooled cylinders shrinking around hot pistons?
Can't imagine enough water to fill the combustion chamber going in on one intake stroke without the throttle being held open and the air filter being removed.

[MrZig]

Okay even after replacing the seals in the petcock, mine is still leaking. And the turnhead is really loose. Argh. I spose its just worn out and needs replacing.

Should I go with an OEM one or are there any cheaper ones that work better? I'd love to go with a cheaper On/Off/Res one.

[bwringer]

Scratch that, a new one would be $100. I can't pay that. Gonna have to keep it as it is I spose.

Where are you getting the $100 number?

Here's the price from flatoutmotorcycles.com :
COCK ASSY, FUEL
44300-44011
$65.02

Still seems spendy -- most petcocks are around $50 - $55 -- but definitely not $100.

[MrZig]

Where are you getting the $100 number?

Here's the price from flatoutmotorcycles.com :
COCK ASSY, FUEL
44300-44011
$65.02

Still seems spendy -- most petcocks are around $50 - $55 -- but definitely not $100.

Well I went to a few different places online and found they were near $80, and since I'm in Canada I figured it would cost around $100 taxes in.