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Discussion Starter · #1 ·
I'd been hoping to do some work on the bike all summer but didn't end up with any spare time so now I'm getting ready to store it for winter. I am trying to figure out the simplest way to drain the fuel tank. From what I understand, having a vacuum petcock prevents me from draining it by simply removing the fuel line from the carb. However, I read that I might be able to disconnect the fuel line from the carb, then suck on it to get the fuel flowing, and drain it that way. Though another post makes it sound like this doesn't work. So my first question then is: which fuel line in the picture below do I disconnect and can I drain the tank with it?
the smaller one on the left or the larger one on the right of this picture?

Font Motor vehicle Automotive tire Automotive exterior Screenshot



If sucking on the fuel line does not get it to drain, it sounds like my next simplest option would be to remove the fuel tank. From what I've read on here, it sounds like it is pretty straightforward. Is it correct that this is all I need to do:
  • disconnect 1 fuel line
  • remove 3 bolts
  • pull the tank out

If it's that easy, my question is again: which fuel line am I removing from the carb and does this line stay connected to the tank when I pull it out? Is there anything else I need to disconnect or watch out for (wires, etc.) when pulling off the tank?

As always, my sincerest thanks to everyone who puts their time into this forum and helps walk people like myself through their bike maintenance. You guys are great.
 

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To remove the tank: There is one fuel line from the petcock to the carb. Disconnect that at the petcock. Disconnect the vacuum line from your petcock. Remove three bolts (one is under the seat) and remove the tank.

To drain the tank, on or off the bike: There are two small diameter lines attached to the petcock, one is the vacuum source, one is a vent line. If you blow into the vent line fuel should flow out if the petcock is turned on. Alternatively, disconnect the vacuum line and suck on it. Again, fuel should flow out.

Another alternative would be to remove the petcock. This has the possibility of becoming quite messy.
 

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Discussion Starter · #3 ·
Thanks for the quick response! Yeah, I definitely want to avoid removing the petcock if possible.
So, if I'm understanding this right, the simplest way of doing this would be to disconnect the vacuum line at the petcock, attach a length of hose to the vacuum line, suck on it, and let it drain into a gas can. Is that right?

To make sure I've got my lines correctly identified, the vacuum line is the small diameter line on the left
Automotive fuel system Automotive tire Motor vehicle Automotive wheel system Vehicle



the fuel line to the carb is the larger diameter line on the right,
Vehicle Automotive fuel system Motor vehicle Automotive tire Gas



and my vent line is a small diameter line that runs from the petcock down to beneath the bike
Water Vertebrate Plant Drinkware Bottle
 

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Yes, you have the lines identified. I think that it would be easier to apply air pressure to the vent line, using something like a bike tire pump or basket ball inflator unless you have a vacuum pump. How easy it will be depends on how much fuel remains in the tank at present.
 

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Just curious I might not have read it but why do you want to remove the gas? If stored in say a garage top it off and add stable or I guess if you drain it you might want to know the guys suggestions on fogging the tank because you don't want to gain rust.

Everyone has their own method. I'm a top it off, maybe a bit of stable and battery on a tender guy.
 

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Discussion Starter · #6 ·
Thanks, I'll take your advice and dig around for an old bike pump. The tank is about half full of fuel.
So the step by step would look like this:
  • attach bike pump to vent line
  • disconnect fuel line from petcock
  • attach hose to petcock fuel line nipple and run to an empty gas can
  • turn petcock to REServe
  • pump air into system through vent line
  • fuel flows through fuel line and into a gas can

Apologies for my confusion with this stuff, I understand the basics of the petcock but I'm completely lost on how the vacuum plays into it.

why do you want to remove the gas?
Well, I had the bike running at the start of the summer but it has some issues I need to fix and ended up sitting too long. I haven't had any time to tinker on it and it's supposed to snow this weekend. So now it has old gas in it that I want to get out of there before storing it. Last year I had it in a storage unit with a full tank and stabilizer. But since I'm already going to take the gas out, this year I thought about keeping the tank stored inside because I read that was a preferred method. If fogging the tank is gonna be a process though, maybe I'll just fill it back up with fuel and stabilizer again this year. I really just need a place I can work on it but we only have a gravel driveway so... into storage it goes for 8 months of the year.
 
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Here's some secondary info for you that you may or may not need. The stock petcock I believe can be converted to pseudo manual. If I remember right you take out the screws and flip the spring. But of course you probably can't do that with gas in the tank.

Second option is I hate the vacuum petcocks and you can just buy a manual petcock and install it. Then all you have to do is plug the vacuum port on the right side of the carbs with a rubber vacuum port block off. or a capped piece of rubber hose. This is what I do.

If you're going to drain the tank and store it inside just get a funnel and your gas can and pull the petcock. Sometimes people waste to much thinking or time on keeping clean or not making a mess when making a mess can be done and cleaned up faster.

I recently lined a tank that I learned had a few gallons of gas in it. I tried to manually drain it through a hose but it was taking forever. I ended up getting a 5 gallon bucket and pulled the petcock and I was done in a few minutes. Then dispose or use the gas how you like.
 

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Apologies for my confusion with this stuff, I understand the basics of the petcock but I'm completely lost on how the vacuum plays into it.
The vacuum petcock will not flow fuel, even when turned to the open or reserve position, until a vacuum is applied to the vacuum port of the petcock. The vacuum operates on a rubber diaphragm, pulling it away, against spring tension, opening a port which allows fuel to flow.

The vent line is there in case the diaphragm perforates or doesn't seal properly and lets fuel past. The vent drains the fuel to ground. Applying pressure to the vent line forces the diaphragm to open. It does not take much pressure, but the pressure must continue throughout the tank draining process.
 

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If you do store the tank empty, I suggest removing the petcock so it can breathe. On the occasion that I actually winterize my Standard, I leave the manual petcock open with the fuel line disconnected and the filler cap off. (The hinged cap cover keeps the critters out.)
You could swish around some dry gas or isopropyl to remove excess water. The blast it with a couple shots of fogging oil to coat the inner surfaces.
 

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I have an old snowmobile primer bulb that I used to use to supply vacuum to open the vacuum valve (I changed to a non-vacuum petcock a few years ago so I don't need to use it on the CX now). It would keep the valve open for quite a while but I did give it another squeeze every so often

FWIW, the vacuum petcock has 2 valves. The manually operated one is exactly the same as in a non-vacuum petcock. The vacuum valve controls whether fuel can gt from the tank to the main valve and is only open when the engine is turning fast enough to produce vacuum so that fuel flow will stop if the engine stalls (perceived as a safety feature so less fuel will spill if the bike lands on its side during an accident).

Re draining the tank for storage, I have 3 good reasons for not leaving the tank & carbs full, with or without stabilizer:

1) Have you ever seen what happens to gasoline if it is left in a tank for several years? Even the best fuel stabilizer is only good for a few months before the fuel starts to evaporate. First the fuel turns to jelly, then it hardens. It's not pretty and not easy to clean out.

Can you absolutely guarantee that you will be taking the machine out of storage again in 6 months or less? I have left bikes stored for several years on a few occasions, and it wasn't always planned. My GoldWing's original owner had a workplace injury during the winter that ended his use of motorcycles and the bike ended up "stored" for 10 years (6 of them outside) before I got it and I stored it in my garage for 2 more before I put it on the road. Before I filled it I looked inside the tank & it was as clean as when it came off the line in Marysville in '83. It has been drained every winter since then and it was still clean & shiny inside the last time I looked.
My GoldWing parts bike was stored with the tank full (+ stabilizer) for 2 or 3 years; The stuff that came out of it smelled rank and the tank would need a lot of effort before it was usable.

2) During normal use a certain amount of moisture finds it's way into a fuel tank from filling up in the rain, condensation from moist air entering the tank due to driving on a rainy/humid day, &c. Water is heavier than gasoline. If you leave the tank full the water can never evaporate. If it can't evaporate it will eventually find another way out (this is why tanks always rust out at the lowest point).

3) I don't need to tell you how dangerous the fumes from a vented fuel tank can be if your garage is also your shop. Not to mention the spill if it gets knocked over or the tank rusts out & starts to leak.

I usually drain the tank as much as possible and then connect it back to the carbs, start the engine and let it run until it dies to extract every drop possible from the tank and open the carbs' drain screws 1/2 turn for a few seconds to let the last few drops out of them. After that I leave the cap ajar for a few days to let any fuel left in the tank evaporate, followed by the water.

BTW: If the original plating inside the tank is intact fogging it should not be necessary.
 

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1) This evaporation and varnish formation is accelerated by ethanol (no matter how much you argue that corn-beer is trouble free, Bob. 😇) Seafoam, used as a solvent rather than an additive, dissolves the varnish better than anything I've found.
2) This is why I suggest the dry gas rinse. It will bind with water in the seams and carry it away when it evaporates.
3) I will usually leave the tank open to breathe until I refill it. There are times of high humidity in the garage during the spring melt, so I like the extra protection of fogging.
 

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Even ethanol free gasoline will evaporate if left in a vented tank for a few years.

You know that most of the stuff people blame on alcohol in the gas is caused by either age, neglect or manufacturers who don't pay attention to what is in the fuel that is available.
Personally, I feel that adding alcohol to gasoline is a waste of time & effort done solely to make people feel that they are helping to solve a problem. The only real benefit of alcohol in motor fuel is that gas line anti freeze is no longer needed.
 

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Discussion Starter · #13 ·
Thanks everybody. As always, I appreciate getting to hear different perspectives from so many knowledgeable folks.

The vacuum petcock will not flow fuel, even when turned to the open or reserve position, until a vacuum is applied to the vacuum port of the petcock. The vacuum operates on a rubber diaphragm, pulling it away, against spring tension, opening a port which allows fuel to flow.
As soon as I read that, something just clicked for me and it all made sense. I ended up getting the tank drained just fine by disconnecting the fuel line and attaching a new one from the petcock into a gas can. Then created some pressure on the vent line through a combo of kitchen syringe, duct tape, and half broken tire pump. I had read someplace that the vacuum can actually be kinda fragile so I was a little slower pumping than I otherwise might have, but it worked out great.

Regarding storage, I think that I'm going to opt for storing the bike with a full tank with fuel stabilizer in it. Part of the decision is just a matter of not having the time to do everything I'd like to. But I also know for a fact that the bike will be coming out of storage in less than 9 months because our neighbor can only store it through Spring. At that point, I can either get the bike running again or drain the tank and pull it if it seems like the next storage will be more long term. Pulling the tank feels less intimidating now that I've gotten so much info on how to clean and protect it when that day comes. Until now, I hadn't really known what happens when gas "goes bad," I just knew it wasn't good.

I'm hoping that one of these days I'll rent a place with a garage/shop where I can pull things apart and give the bike the work that it really needs (stator). But until then, it's gonna be bouncing between storage spaces each winter.
 

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If you are going to keep a bike that is 4 decades old in running condition you pretty much need to have somewhere to work on it or take your chances finding a mechanic who is able to do the work (which will require deep pockets).
 

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At least you have a sheltered place to put it up for winter.
 

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Everything I have read here is good but I think there is an easier way, they sell a siphon at Home Depot that you can suck the gas out with. You can get 98% of the gas out with little problem, then run the rest out if the bike runs so as to get the gas out of the carb. No gas in the gas tank no gas in the carb and get rid of the old gas so no one uses it by mistake. Even if you are planning to leave the tank full turn of the fuel and run the carbs dry, it saves a lot of problems down the road. Also if you can find ethanol free fuel you can skip the stable and the gas will be good for two years as a rule. I have started cars that have been sitting for five years back before the screwed up the gas.
 

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I drain my fuel into the gas can and run the snowblower on it. Without the added corn-beer, it doesn't go bad The remainder goes back into the bike, come spring.
 

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Ethanol has little effect on fuel life. Read this. All the way through.
Over half of small engine repairs are thanks to bad gas. The manufactures of small gas powered lawn equipment has been pushing the use of non ethanol fuel for a number of years, even the ones that are not selling the product. I just happen to be in that business. When a lawn mower or any small engine shows up with running problems the first thing they check is the gas and over half the time just replacing it with new gas solves the problem. Some carbs are more likely to be effected then others but on the whole small engines have a real problem with old gas. The big problem is water, the ethanol will pull it out of the air and it will start being a problem as early as thirty days out. Even without ethanol modern gas will go bad pretty fast. Does gasoline go bad? | Live Science. The real question is why take the risk of having problems? If the majority of the experts say keep your gas fresh why would you want to keep old gas around?

Edited by Sidecar Bob: Quote fixed
 

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But as Mike says in his article the problem isn't caused by the ethanol being added to the fuel but by lack of the volatile solvents that are no longer being added to it
Have you ever heard of gas line anti freeze? It is an alcohol that you add to gasoline so that it will absorb any water in the tank and carry it through the system so that it doesn't freeze and block the fuel line or harm the fuel pump.

I'd bet that a lot of the water found in the fuel tanks of small motors has more to do with storing them outside where they are rained on than with ethanol. Some years ago a co-worker asked me to see why their mower wouldn't start and when I looked to see if it had gas I saw a big bubble of water at the bottom of the tank. As you described, it ran fine once I replaced that with fresh. I asked where they kept it and was told that it sat under the back steps when not in use so I told them if they couldn't store it under a roof they should at least put something over it to keep rain from getting into the vented gas cap and that solved the problem.

I haven't seen fuel without ethanol for sale in at least 30 years and I've never had problems with my mowers or snow blower that were caused by water in the fuel. But mine are all kept in the shed or garage when not in use.
 
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