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Discussion Starter #1
Hey everybody, I'm Jen, a total newbie here. Both to the board and to motorcycles in general. So I took the class, got the license, bought the bike (a lovely '99 Shadow Aero VT1100). It was delivered yesterday and is GORGEOUS!! However, my new helmet wasn't here yet - so only my boyfriend could take her for a spin. I noticed last night that something smelled funny when I got home, but shrugged it off. Tonight when I got home it was definitely a gas smell. When I opened the garage door - wow. So I found a flashlight and checked out the petcock and sure enough, it was still 'On'. So I turned it to off and opened the garage door halfway. Now - is everything ok? Should I let it sit overnight to air out and start it tomorrow? Should I start it now? Will it start? Thanks a bunch!

Jen
 

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Okay, now I'm the newbie with the question. But I leave the petcock in the "on" position all the time and I've never smelled gas. Do people really turn it off every time, and is leaving it on a risk?
 

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Welcome to the forum.

You should not smell gas with the petcock in the on position. Look under the petcock and check for dripping gas. The VLX Shadows had a recall for this. Maybe your bike has a similar issue.
 

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I'm going to answer this question, because even though it's in the tech section it's general motorcycle knowledge (or it should be) and if you do the wrong thing in this situation you can cause serious damage to your motor.

If your petcock is seeping gas out onto the exterior of your bike that is one thing and needs to be fixed. But if you get a strong gas smell and you don't see any obvious fuel anywhere around the petcock you need to look further.

Lots of riders leave their bikes petcock on all of the time with no ill effect. Some bikes even have a vacume operated petcock that only opens when the engine is spinning.

The problem with leaving the gas tank valve open occurs if/when the fuel inlet needle stays open for some reason (debris in the seat area or a failed float) allowing gas to pass thru the carbs and into the engine, perhaps filling it completely with liquid gasoline. If you try to start the engine with the cylinder even partially filled with liquid there is a very good chance that you WILL bend/break a piston or connecting rod. Both of these are bad things. Air in your engine will compress into a smaller space. Liquid will not.

If that doesn't happen and the excess gas makes its way into the crankcase it can dilute the oil in the engine so far that bearing surfaces no longer have any oil protection, destroying your motor in that manner. ( I have wrecked an engine this way )
An overfull crankcase due to gas contamination can also bend/break things when the engine is started.

Lots of people seem to think that the vents hoses on the carbs are there as overflows in case this happens. Not so. The vents are there as vents, period. The carb won't function properly without them.

If you suspect this has happened to your scooter, and there isn't a big lake of gas on the ground around your bike....check the oil. If the level is high or the oil seems thinner than it should be or it smells like gas DO NOT TRY TO START YOUR ENGINE. You have some work to do. The oil has to be drained as does any fuel in the cylinders, plus you need to find out why the inlet needle leaked.

Because of the design of most motorcycles not turning off your petcock is always a risk. Most people will never have an incident like this occur, so they always leave the gas on. I used to never turn mine off either, but I've had 5 or 6 rides fill themselves up with fuel due to a hung up inlet needle and it a pain in the azz to clean up. Even now I only turn mine off when I'm done with the bike for the day.
 

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I'm going to answer this question, because even though it's in the tech section it's general motorcycle knowledge (or it should be) and if you do the wrong thing in this situation you can cause serious damage to your motor.

If your petcock is seeping gas out onto the exterior of your bike that is one thing and needs to be fixed. But if you get a strong gas smell and you don't see any obvious fuel anywhere around the petcock you need to look further.

Lots of riders leave their bikes petcock on all of the time with no ill effect. Some bikes even have a vacume operated petcock that only opens when the engine is spinning.

The problem with leaving the gas tank valve open occurs if/when the fuel inlet needle stays open for some reason (debris in the seat area or a failed float) allowing gas to pass thru the carbs and into the engine, perhaps filling it completely with liquid gasoline. If you try to start the engine with the cylinder even partially filled with liquid there is a very good chance that you WILL bend/break a piston or connecting rod. Both of these are bad things. Air in your engine will compress into a smaller space. Liquid will not.

If that doesn't happen and the excess gas makes its way into the crankcase it can dilute the oil in the engine so far that bearing surfaces no longer have any oil protection, destroying your motor in that manner. ( I have wrecked an engine this way )
An overfull crankcase due to gas contamination can also bend/break things when the engine is started.

Lots of people seem to think that the vents hoses on the carbs are there as overflows in case this happens. Not so. The vents are there as vents, period. The carb won't function properly without them.

If you suspect this has happened to your scooter, and there isn't a big lake of gas on the ground around your bike....check the oil. If the level is high or the oil seems thinner than it should be or it smells like gas DO NOT TRY TO START YOUR ENGINE. You have some work to do. The oil has to be drained as does any fuel in the cylinders, plus you need to find out why the inlet needle leaked.

Because of the design of most motorcycles not turning off your petcock is always a risk. Most people will never have an incident like this occur, so they always leave the gas on. I used to never turn mine off either, but I've had 5 or 6 rides fill themselves up with fuel due to a hung up inlet needle and it a pain in the azz to clean up. Even now I only turn mine off when I'm done with the bike for the day.
Couldn't said it better myself. Do check it out. This is not normal from my experiece. Welcome to "Asylum".
 

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I'm going to answer this question, because even though it's in the tech section it's general motorcycle knowledge (or it should be) and if you do the wrong thing in this situation you can cause serious damage to your motor.

If your petcock is seeping gas out onto the exterior of your bike that is one thing and needs to be fixed. But if you get a strong gas smell and you don't see any obvious fuel anywhere around the petcock you need to look further.

Lots of riders leave their bikes petcock on all of the time with no ill effect. Some bikes even have a vacume operated petcock that only opens when the engine is spinning.

The problem with leaving the gas tank valve open occurs if/when the fuel inlet needle stays open for some reason (debris in the seat area or a failed float) allowing gas to pass thru the carbs and into the engine, perhaps filling it completely with liquid gasoline. If you try to start the engine with the cylinder even partially filled with liquid there is a very good chance that you WILL bend/break a piston or connecting rod. Both of these are bad things. Air in your engine will compress into a smaller space. Liquid will not.

If that doesn't happen and the excess gas makes its way into the crankcase it can dilute the oil in the engine so far that bearing surfaces no longer have any oil protection, destroying your motor in that manner. ( I have wrecked an engine this way )
An overfull crankcase due to gas contamination can also bend/break things when the engine is started.

Lots of people seem to think that the vents hoses on the carbs are there as overflows in case this happens. Not so. The vents are there as vents, period. The carb won't function properly without them.

If you suspect this has happened to your scooter, and there isn't a big lake of gas on the ground around your bike....check the oil. If the level is high or the oil seems thinner than it should be or it smells like gas DO NOT TRY TO START YOUR ENGINE. You have some work to do. The oil has to be drained as does any fuel in the cylinders, plus you need to find out why the inlet needle leaked.

Because of the design of most motorcycles not turning off your petcock is always a risk. Most people will never have an incident like this occur, so they always leave the gas on. I used to never turn mine off either, but I've had 5 or 6 rides fill themselves up with fuel due to a hung up inlet needle and it a pain in the azz to clean up. Even now I only turn mine off when I'm done with the bike for the day.
+1

I have the same problem with a stuck something in the carb, but I always turn my petcock off when I stop. Figure its easier to just do that then pull apart everything.

Crash
 

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I pulled my tank the other day, ran a hose from the petcock into a jerry can and turned it on. NOTHING came out. Not sure if that is because I have a newer (2008) bike or not, but could it also be an issue with the petcock as well as the carb? Or are the older petcocks a free flow design?
 

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Two Bikes out in the barn ~ one has a carb that overflows, I shut off the fuel feed...
The Shadow has no problem with the petcock ON all the time, except when the tank gets low enough fer Reserve to be used...
HOWEVER ~ if I shut OFF the petcock, it doesn`t !!!(shut off)
I found this oput once when I hadto pull the tank...
Welcome to the forum, You need to find out where the gas is coming out fer you to smell it...
Welcome,
Dennis
 

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Discussion Starter #14
Hey everybody, thank you for the replies and the welcomes. :)

Worst case scenario was thankfully not the case here. Turns out the petcock *may* be a little leaky - but overall we think the issue was the full tank o' gas and being brought straight back home and put on the side stand. They think that caused the overflow valve to give off a wee bit of gas. I was skeptical that that was all there was to it, but I've taken the bike for a few rides since and everything was fine. Also, we had a few nice days here in Tennessee and I had the AC off. When I turned it back on I smelled gas again. So I guess that was all there was to it. The initial overflow fumes getting caught up in my air conditioning. /shrug. I am really glad to report that for me, for now - this didn't wind up being a disaster. :) Cheer!!

Jen
 

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Discussion Starter #15
Oh, and if there was any chance I'd ever leave that sucker On - I think the odds have been reduced to zero at this point. That's one way to reinforce a point on the first day you own your bike! lol
 

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gat803, I am new to this forum and purchased a 2003 shadow spirit for my wife last year. I noticed last week that her petcock was leaking and am in the process of replacing it with a pingle. I read your explanation of the potential problem which I have been told is called hydro-lock. I am wondering however , how this could happen to a bike with a fuel pump such as mine. Do some of the shadows have a gravity feed system? I also have a Valkyrie which does not have a fuel pump and there is much concern about hydro-lock on that bike. I guess Honda figured that the vacuum petcock was the solution and I guess it is if it does not fail. Do I have this situation assessed correctly or am I missing something that I should take precautions against on the spirit. Thanks for your help.
 

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I am wondering however , how this could happen to a bike with a fuel pump such as mine.

It's been my experience that fuel will gravity feed thru a diaphragm style fuel pump. (this is the type of pump used by many motorcycle OEM's w/o fuel injection)

Keep in mind that the flow rate is generally NOT sufficient to operate the engine in the event of a fuel pump failure (yes, I have first hand experience of that....on the expressway) but a bike setting over night (fuel pump equipped or not) with a faulty carb inlet needle does have the potential to gravity feed itself to drowning.

I'm not suggesting that everyone shut off their gas valve every time you step off your bike. Again, chances are good that most people will never flood a motor in this fashion. But I have had it happen enough that I now turn off the gas when I park the scoot for the night. Especially now that my main ride has four carbs. ;-)
 
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