Turning off Gas

[Nightsbane]

They talked about this in the MSF course. Should I turn off the gas each time I am done riding? Or should I only do this when not driving for extended periods. The MSF guys said to do it even when heading into a restaurant to eat, and I thought that sounded perhaps excessive.

Thoughts?

[grego]

nightbane
there is no off on a gz...only reserve,prime and on.. the gas is sucked out of the tank by the engine. i found that out when someone was telling me how to remove the gas tank.....and sure enough when i removed the hose nothing came out...also was informed to get a can of seafoam which is a gas treatment and follow the directions on the can. double it the first time and then a normal dose depending how much you use the bike. am sure someone will help me out here and explain it better am a newbie myself.

safge biking grego

[blaine]

They talked about this in the MSF course. Should I turn off the gas each time I am done riding? Or should I only do this when not driving for extended periods. The MSF guys said to do it even when heading into a restaurant to eat, and I thought that sounded perhaps excessive.

Thoughts?
I think this is one thing that they teach wrong,and should be updated..Petcocks now days are vacuum operated,and shut the fuel off automatically.Even the petcocks that do have a "off" position,rarely need to be used.My bike is 21 years old and the petcock is vacuum operated,and has no "off" position.
:) :cool:

[geezer]

all bikes are different and as a general rule yes close the valve. it prevents bad carbs from being able to flood your engine full of fuel. but no not on the gz you cant

[blaine]

all bikes are different and as a general rule yes close the valve. it prevents bad carbs from being able to flood your engine full of fuel. but no not on the gz you cant
Please explain how the vacuum operated petcock on the G.Z. is different from that on all other bikes.How do you "close the valve" on a petcock with no "off" position?
:??: :)

[geezer]

you mean how the gz petcock is different from other non vac petcocks? sure, leaving a normal one open wil let fuel flow past it if you have a leaky needle valve, depending on carb placement (above, Below, Next to the intake manifold) fuel will drip past into te cylinder, past the rings and into the crankcase. even th vac ones can fail if the diaphrame goes

[blaine]

you mean how the gz petcock is different from other non vac petcocks? sure, leaving a normal one open wil let fuel flow past it if you have a leaky needle valve, depending on carb placement (above, Below, Next to the intake manifold) fuel will drip past into te cylinder, past the rings and into the crankcase. even th vac ones can fail if the diaphrame goes
Agreed.But I was talking about a vacuum operated petcock,which the majority are now days.Also I have never seen a non vacuum petcock without a "off" position.
:cool:

[alantf]

non vac petcocks?

There is no such thing as a "non vac petcock". A petcock, by its very nature, is designed to switch from "no flow" to "flow" by engine vacuum - thereby making it unnecessary (impossible) to have to switch off. This is why it was designed - so that you didn't have to fiddle with the valve every time you switched off. Older bikes did not have the benefit of this modern invention, so we had a simple on/off valve that we had to switch off every time we parked the bike. The two things are entirely different, so somebody on the course is YEARS out of date. I just hope it wasn't one of the instructors, or I'd be wondering just how much knowledge he actually had. :sad:

[blaine]

I just hope it wasn't one of the instructors, or I'd be wondering just how much knowledge he actually had. :sad:
"The MSF guys said to do it even when heading into a restaurant to eat, and I thought that sounded perhaps excessive."
The instructor needs to be instructed. :) :roll:

[geezer]

i missunderstood you blain sorry. my fzr is a non vac petcock. what are you trying to say alantf? are the valves that are not vacuum operated have a different name?

[5th_bike]

There is no such thing as a "non vac petcock".
Sure there is, my 50 cc mopeds had a non vac petcock "on" and "off". No reserve as far as I remember.

The 35 cc Solexes didn't have a petcock at all. The gas just got vacuumed into the carburetor and flowed back when the engine went off. They also didn't have a float with needle nor associated problems.

[alantf]

What I meant was that a "petcock" is vacuum operated. If it's not vacuum operated it has another name. I agree that if it's the old type, that was just a manual switch, then yes, I always used to switch off whenever I turned the engine off. I always got into the habit. But, offhand, I didn't know that there were any modern bikes that still had the old type. Even the geezer, which is just about the cheapest bike on the market, has a vacuum petcock, so it seems that the instructor is years out of date, or just plain & simply doesn't know what he's talking about. Perhaps you could ask him to name any modern bike that uses the old system, to see how extensive his knowledge is. :)

[geezer]

so if its not vac its not a petcock? ok let me go tell everyone i know this new bit of info :lol: anyway if you werent aware most people with vacuum petcocks tend to delete the system all together due to age and diaphrams going out, like on my old 83 midnight maxim. i converted cause fuel was leaking. lots of harley riders also swap due to theres being unreliabe. so here in america only i guess the valveswithnoname i shall refer to them as now are still very alive and kickin

[blaine]

so if its not vac its not a petcock? ok let me go tell everyone i know this new bit of info :lol: anyway if you werent aware most people with vacuum petcocks tend to delete the system all together due to age and diaphrams going out, like on my old 83 midnight maxim. i converted cause fuel was leaking. lots of harley riders also swap due to theres being unreliabe. so here in america only i guess the valveswithnoname i shall refer to them as now are still very alive and kickin
I would buy a rebuild kit,before I ever reverted to the old style of petcock.(also cheaper) Harley had a known problem with their vacuum petcocks,because the high vacuum of the engine,kept rupturing the diaphram's in the petcock.

:) :cool:

[FutZ]

petcock - regulator consisting of a small cock or faucet or valve for letting out air or releasing compression or draining
regulator - any of various controls or devices for regulating or controlling fluid flow, pressure, temperature, etc.

A petcock is still a petcock with or without vacuum. The only difference is a spring loaded diaphragm that will engage when vacuum is lost to prevent flow.

Off=Off
On=Flow if Vac Present or on Non-Vac flow until the float stops it.
Pri=Flow until the float stops it.
Res=On, but uses a secondary inlet that is lower in the tank

On non-vacuum operated, if your float sticks due to lack of maintenance or if it is not adjusted correctly it can fill your engine or go out the carb overflow and leave you stranded. Hence the repeat warnings to “turn it off” as a good habit. This can also happen on Vac operated but only if the diaphragm or spring fails at which point it’s time for new parts and there was nothing you could do to stop it.

If you have an off, use it. It is easier than walking. If you don't have an off (GZ standard is vacuum operated), for the purpose of this forum make sure it is set to On until you run out of gas.

[geezer]

bravo good sir :2tup:

[savrip]

EKG! Sorry I had that screamed at me all weekend.

E-Engine Shut-off
K-Key Off
G-Gas Off

Generally this was for the older bikes, but they teach it to you because it's good to know, and they don't know what type of bike you're riding in the future.

[tulsawalk]

MSF instructor here. I'll take a shot at clearing the mud on fuel valves:

Fuel injected motorcycle = no fuel valve

Gravity fed carburetor = On / Off / Reserve - In the on position the fuel simply gravity feeds from the tank as long as there is fuel. If you have this type of fuel system you always want to turn the valve off when the motorcycle is not running because the needle and float is the only thing keeping the fuel from flooding the carburetor, cylinders and then crank case. If the needle and float fail you have the chance of hydro locking the piston and bending a connecting rod and/or filling the crank case and diluting your oil with gasoline.

Vacuum fed system such as the GZ250 has = On / Prime / Reserve - In the on position the fuel will not free flow to the carburetor. It depends on intake vacuum to open a valve in the fuel shut off valve to allow fuel to flow. The prime position is just what it sounds like. If you bike has been parked for some time it allows fuel to free flow to the carb until the bowl fills and the bike starts. Once started the valve should be returned to the on position. You should never have to use the prime position unless the bike has sat for a time.

The reserve position is just that. It allows you a few more miles to get to a station if you run out of fuel. Of course if you forget to return the valve to the on position after filling up you no longer have the advantage of the extra fuel.

[Gz Rider]

...

[jonathan180iq]

I think the question here is: "Are there any bikes made in the last 20 years that have gravity fed petcocks that require being turned off? Do the manufacturers recommend using off, unless you are performing some type of maintenance?"

Cause, uh, I don't know of any. And of the bikes that I've owned that had the "OFF" option, there was never any reason to use it, unless I was going to remove the tank.

And if there are none, then why do we continue teaching to turn then off?

[Gz Rider]

...

[jonathan180iq]

I agree that the point is valid. It's just dated.

And like you said, if people are riding around with faulty fuel control valves, then they have bigger problems than simply remembering to turn the petcock to "off".

[Water Warrior 2]

The OFF position is a routine safety factor that was taught way back when. My first bike had the OFF position. Even well into the 80's there were dual purpose bikes and off road bikes with an actual off position. I think the safety lesson is just left in there to cover all the bases for the unwary.

[mrlmd1]

If I remember correctly, the Honda Rebel I used in my MSF class 4 years ago had an OFF position, not a vacuum operated petcock.

[blaine]

On the 85 to 90 Kawasaki 454's,they used to different petcocks,both vacuum operated.The first petcock had "off,on,res".The second one had "pri,on,res".I like the second style better,as you can prime the carbs without turning the bike over.With the first style you need the bike turning over to get vacuum to fill the carbs.On the up side the first one has a positive "off" position.My bike has the second style,and when been stored,I remove the fuel line from the carb and plug it.I don't rely on the petcock alone to hold back the pressure of a full tank of fuel.(I always fill tank before storage).
:) :cool:

[Rookie Rider]

When you remove the fuel line to plug it, dont fuel go all over the place and spill ?

[alantf]

No...... Read the whole post :) You'll see that the "run" position takes engine vacuum to open the valve & let fuel flow. On the other hand, if you removed the pipe in "prime", then, certainly, fuel would flood out.

[blaine]

When you remove the fuel line to plug it, dont fuel go all over the place and spill ?
Not on a vacuum operated petcock.The petcock needs vacuum from the engine turning over to open and let fuel flow.If you are on "pri" position,no vacuum is needed and fuel can flow.
:) :cool:

[Rookie Rider]

ahhh ok. Thanks

[Gz Rider]

...

[birdmove]

This confusion on gas "petcocks" can be excused due to the fact that very new riders may never have been exposed to the earlier petcocks that were , and are, gravity fed, engine vacuum having nothing to do with fuel supply on those bikes. Since I'm 57 years old and started riding at eight, almost every motorcycle I've owned has had a gravity fed petcock. With the gravity fed one must develope the habit of twisting the lever on the petcock to the off position when parking the bike. The reason being, that if the needle and seat develope a leak, possibly due to a little piece of dirt, the gas will continue to fill the float chamber, and then will overflow and continue leaking.

But, don't get the idea that vacuum controlled petcocks are trouble free-they most certainly are not! Check that subject of a Suzuki DR200 thread at, say, advriders.com, and you will see that the vacuum petcocks are known to develope leaks and fill the cranckcase with raw gas. Many owners of those bikes replace the vacuum petcocks with gravity ones and simply turn them off when parked. Many DR200 owners even replace the OEM petcock with a gravity fed before any problem developes. Dual sport bikes are often way off the beaten path and owners need to be pretty self sufficient-many dual sport riders are set up to fix a flat on the trail, because noone is going to find them and haul their bikes out to the road.

I prefer a gravity fed petcock any day due to simplicity-just turn it to off when parked and you won't have a problem. The Royal Enfield Bullet still used a gravity fed petcock right up until the new fuel injected model came out. There are other motorcycles still using the gravity fed units also.

Jon

[mole2]

I agree that the point is valid. It's just dated.

And like you said, if people are riding around with faulty fuel control valves, then they have bigger problems than simply remembering to turn the petcock to "off".

The generalization that all "modern" petcocks are vac operated is untrue. I just looked at my 2009 carb V-Star 650 and my neighbors 2007 carb V-Star 1100 and both do not have a vacuum line to the petcock. They both have electric fuel pumps which draws the fuel. Hence the petcocks are flow valves with Off - On - Reserve. Teaching AND utilizing the "turn the petcock off" (on bikes/petcocks that have an off position) is very applicable to bikes made today.


:)

[alantf]

They both have electric fuel pumps which draws the fuel.

So they're both fuel injected, as opposed to carb, right? :)

[mole2]

They both have electric fuel pumps which draws the fuel.

So they're both fuel injected, as opposed to carb, right? :)

No, they're both carb.


:)

[blaine]

The generalization that all "modern" petcocks are vac operated is untrue. I just looked at my 2009 carb V-Star 650 and my neighbors 2007 carb V-Star 1100 and both do not have a vacuum line to the petcock. They both have electric fuel pumps which draws the fuel. Hence the petcocks are flow valves with Off - On - Reserve. Teaching AND utilizing the "turn the petcock off" (on bikes/petcocks that have an off position) is very applicable to bikes made today.


:)
Typically the pump has a built-in pressure-relief valve to keep it from oversupplying the float bowls. When the float bowls fill up, and the float needles rise into their seats to cut off the flow of gas, the pump senses this rise in pressure in the fuel line and stops momentarily starting up again when the pressure in the line drops.

The pump is often connected to the engine's ignition system so that it doesn't pump unless the engine is actually turning over. This prevents the pump from working in case the bike falls over and the engine dies but the ignition is still on. In many Hondas, for example, the pump is connected to a fuel cut-off relay that is in turn connected to the ignition control module. The relay prevents battery current from getting to the pump unless the ignition module is transmitting ignition pulses to the relay indicating the engine is running. No ignition pulses, no current to the pump.
:) :cool:

[Water Warrior 2]

On the Vstrom with fuel injection there is a tip over sensor/relay that will shut off the fuel pump if the bike takes a nap. Probably quite a common safety feature on many bikes.

[mole2]

The generalization that all "modern" petcocks are vac operated is untrue. I just looked at my 2009 carb V-Star 650 and my neighbors 2007 carb V-Star 1100 and both do not have a vacuum line to the petcock. They both have electric fuel pumps which draws the fuel. Hence the petcocks are flow valves with Off - On - Reserve. Teaching AND utilizing the "turn the petcock off" (on bikes/petcocks that have an off position) is very applicable to bikes made today.


:)
Typically the pump has a built-in pressure-relief valve to keep it from oversupplying the float bowls. When the float bowls fill up, and the float needles rise into their seats to cut off the flow of gas, the pump senses this rise in pressure in the fuel line and stops momentarily starting up again when the pressure in the line drops.

The pump is often connected to the engine's ignition system so that it doesn't pump unless the engine is actually turning over. This prevents the pump from working in case the bike falls over and the engine dies but the ignition is still on. In many Hondas, for example, the pump is connected to a fuel cut-off relay that is in turn connected to the ignition control module. The relay prevents battery current from getting to the pump unless the ignition module is transmitting ignition pulses to the relay indicating the engine is running. No ignition pulses, no current to the pump.
:) :cool:

Which means turn the petcock to the off position when you turn the bike off. :biggrin:

By the way, the fuel pump comes on as soon as you turn the key on on the V-Star to pressurize the system. It does not work off of ignition pulses. That means the pump is live as long as the key is on. This means you must turn the key off as well as turning the petcock to the off position when parking the bike. I am sure many other bikes work this way.


:)

[mole2]

On the Vstrom with fuel injection there is a tip over sensor/relay that will shut off the fuel pump if the bike takes a nap. Probably quite a common safety feature on many bikes.

I wonder if they have that on the Stars. I'll have to research that. :biggrin: I know they have it in cars and boats.


:)