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Big Dumb Viking
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597 Posts
Discussion Starter #1
I am having an issue with POOGS and finding Gas Tank Vent Tube Entrance.

I was following this thread:

http://www.vn750.com/forum/showthread.php?t=17572

...but for the life of me, I cannot locate the Gas Tank Vent Tube Entrance, which is supposedly here:

Locate the gas tank vent tube entrance; a small hole located on the gas tank directly in front of the opened gas cap hinge.
Here are some images of my gas cap, both on and off:










Help please?
 

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Premium Member
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4,778 Posts
Yours is missing! Is there a vent hose coming off the bottom of the tank?
 

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Big Dumb Viking
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Discussion Starter #3

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Near your meat and 2 veg when sitting on the bike :). Like when you take off the seat to look at your battery. Should be the only hose visible down there. At least that is what I always thought that hose is.
 

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Linkmeister Supreme
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7,960 Posts
It is a short (perhaps 3/4" long), small diameter steel pipe sticking out the back of the tank just above the rear mounting bracket. You can see it in the first picture on this ebay auction.
http://cgi.ebay.com/ebaymotors/Kawasaki-1986-VN750-Vulcan-VN-750-Gas-Fuel-Tank-/360313303201?pt=Motorcycles_Parts_Accessories&hash=item53e458b0a1

I believe tanks with two vent hoses are California models.

Some of the earliest models may not have any vent hoses.
They just vent through the cap somehow. Not 100 % sure how this works. :confused:
 

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Super Moderator
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11,934 Posts
Looks like it is missing to me too...unless someone filled it in and painted over it.

It should be right where the hole is on the hinge right between the mounting screws to the tank It looks like you have the correct gas cap for one.... but the hole is missing.

Is it possible someone replaaced the gas cap with a newer one at some point?

KM
 

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Big Dumb Viking
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597 Posts
Discussion Starter #7
It is entirely possible someone did replace the gas cap in the past... I've no idea. I've not changed it since I got it.

Maybe the earlier models didn't have the vent tube?

Guess I'll be cleaning out the gas cap thingy listed in the original POOGS thread. See if that helps.
 

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Super Moderator
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If you look at your last photo...you can see a small nipple thingy on the hinge that sits between the two philips screws on the cap...this fits down in the hole I mentioned before.

I believe early caps did not have this and it is possible your cap is trying to vent to the non exsistant hole. I don't know if that nipple thing is removable.

Will look at my VN tank and see if there is another solution.

KM
 

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Heading to the DARKSIDE!
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177 Posts
My original '86 tank was just like that. YES.....The early tanks did not have the internal vent tube!!! That is why I went with a newer model tank with the tube. When I filled up the tank on hot days under the awning at the gas station.....everything was fine. As soon as I would pull out from under the awning in the sun the sun's heat on my black gas tank would make the gas expand and go through the cap drain to the non existent tube and pour all over the top a side if the tank pouring on the hot engine. Your bet solution is to take the gas cap apart and clean all of your air passages really well with carb cleaner and a tooth brush. My bike eventually did what yours is doing and when you would park it, you would hear a faint whistling/squeeling sound coming from the gas cap. It was the pressure difference.....very slowly equalizing.
 

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Super Moderator
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First off....all tanks were prone to "whistling"... the issue was not a clogged or missing vent ..but just too tiny of a hole for expanding gasses to go through.


I looked at my VN750 tank and the nipple thing is not removable.. I am only guessing here that the early tanks without the vent did not have this, would need someone with an older non vented tank to take a photo....but...

I'd still take apart the cap and clean it. Perhaps you can grind the nipple off so the cap just vents to back of the hinge under the cap.........

KM
 

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If this is an 85-87 model, then it does not have a vent tube by design. Therefore, the instructions I posted will not work. I'm not sure how those models are vented, and no one has offered to tell us. Tag, you're it!
 

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Big Dumb Viking
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597 Posts
Discussion Starter #12
Mine is a 1989 model.

I've *no* idea if this is the original gas tank / cap or not.

I'm going out on a limb, but I'm guessing it was made from the factory with an older style tank (like they still had some lying around from earlier production), but with the newer style cap. I could be wrong though...

I'll go over the gas cap and try cleaning it...will give me something to do tonight. Planning a good ride tomorrow...so we'll see.
 

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Heading to the DARKSIDE!
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My original '86 gas tank had the "nipple thing" on the gas cap to go into the pipe for the vent pipe/hose....yet the tank did not have the internal pipe? I don't know if the gas cap on my old tank was a replacement one or not. All I know is the tanks without the internal vent pipe were a horrible design. When the gas expands.....it has no where to go but spill out the gas cap vent to the non existent pipe that should be there and spill all over the tank. At least with the pipe design ...when the gas expands, the excess will just flow down the hose and drip on the ground.
 

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Big Dumb Viking
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597 Posts
Discussion Starter #14
Well, I took the gas cap apart and cleaned it like in the original POOGS thread.

Hope this will help.

Definitely don't have a gas tank vent tube though. :(

Odie well.
 

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I believe that the gas cap vent exit mystery for 85-87 models can be found in one of asprand's pictures. Click on the image below to enlarge and look for a red arrow. Note there appears to be an impress of a vent port leading to the rear of the gas cap.

Thank you asprand for the great high quality picture!

85thru87gascap.jpg
 

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Patriot Guard Rider
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825 Posts
POOG's has struck my bike. My temporary fix is to leave the gas cap ajar until I fill up again. :doh:
 

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Big Dumb Viking
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597 Posts
Discussion Starter #17
Well, today I put over 100 miles on the bike, riding with a friend. Never encountered the POOGS issue. Perhaps my cleaning of the cap last night fixed it?
 

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Patriot Guard Rider
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825 Posts
I updated the POOGS sticky post to include the '85-'87 model venting updates. 15 minutes is all it takes to fix POOGS. Safer than leaving the gas cap open.
Thanks, but I unfortunately have an '86 California bike. :doh:
 

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Thanks, but I unfortunately have an '86 California bike. :doh:
Cleaning the gas cap vent of a CA model should be similar to that of a non-CA model. The tiny vent hole leading to the fuel separator/check valve is really small and easily plugged. So, I would suggest following the gas cap vent cleaning instructions for the non-CA model and flushing the gas tank vent tube from it's exit point to the CA emissions stuff. Just disconnect the gas tank vent tube from the exit point of the CA emission stuff and spray cleaner down it until you see drips on the floor. That my solve your POOGS problem. If not, then you have at least isolated the issue to the CA specific items (i.e., charcoal canister, purge valves, etc.). If that's the case and you figure out how to clean the CA emission stuff, then shoot me a PM and I'll add it to the POOGS sticky.
 
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