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Gas cap question
Can someone answer this question please.

my name is tim and i am an 18 year old with a 1984 aspencade. i
was wondering it these bikes had vented gas caps. i was reading in one of
the threads that someone drilled a small hole in theirs so it would vent.
when i open my gas cap air rushes into the tank. i was wondering if i
needed a new gas cap
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#1 02-07-2009, 04:06 PM,
I believe that the cap on our Wings is set up to contain the escape of gas fumes for emissions control but to allow the inlet of air to displace the gasoline that is consumed. Drilling a hole in it allows vapors to escape into the atmospere.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#2 02-07-2009, 04:13 PM,
?????????? Has someone Hacked Vic's ID/password?????????? Confusedhock: Confusedhock:
1985 Limited Edition
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#3 02-07-2009, 04:15 PM,
Is'nt the gas cap on a spring loaded ingress port... I thought this was required so that gas would not leak out if the bike when laided down... A simple pressure/vacuum test of the cap would verify the vent to be OK or not... I too get a air sound when I open the cap, but it seems to be a pressure related air difference rather than a vacuum related one... Every once in a while I give mine a hosing with WD40 though... Seems to keep the corrosion on it to a minimum and makes it easier to twist on and off too...
Ed Zogg
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#4 02-08-2009, 09:48 AM,
Hi Folks. I have an '83 1100 and I have been wondering the same thing lately. Mine runs o.k. for the first while and then loses top end performance. I noticed my fuel filter is only getting a trickle of fuel and is virtually empty when running. When i first open my petcock it will quite often fill the filter but other times not. I think the pump is o.k. but not 100% sure.I'll check it soon but the last time it ran out of power on the highway I opened the gas cap as I was riding and it did seem to help!! It's a mechanical pump on mine. Seems like there isn't a lot of others who have experienced this problem. Any opinions are welcome and appreciated. Happy Trails.
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#5 08-06-2009, 06:37 PM,
bob NE In. Wrote:
roscoepc Wrote:?????????? Has someone Hacked Vic's ID/password?????????? Confusedhock: Confusedhock:

I think Vic pasted the question from elsewhere. Notice the word "Can" is capitalized,but there is no other significant punctuation in the actual question. Vic was raised in a long forgotten era when people started a sentence with a capitol letter and ended a sentence with a period.

Thanks for noticing Bob.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#6 08-06-2009, 10:41 PM,
admin Wrote:I believe that the cap on our Wings is set up to contain the escape of gas fumes for emissions control but to allow the inlet of air to displace the gasoline that is consumed. Drilling a hole in it allows vapors to escape into the atmospere.

Sorry Vic, I must disagree.

I guess Tim's original cap had a check (one way) valve letting air in but blocking back, vapor flow. However, if the materials of which the check valve is made gets degraded over time, or dirt completely blocks the valve then either he needs a NEW cap -- has to drill a small hole for equalizing the inside and outside pressure of the gas tank.
[Image: Akriti2450x338.jpg]

" ... If you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas." ~ George Bernard Shaw (1856-1950)
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#7 08-07-2009, 12:29 PM,
I've had a long hard day and I'm exhausted so not I'm going to go into great detail at this on the importance of keeping the fuel system sealed on a GL1200. What I will say is that liquid gasoline as it turns to vapor expands many, many times after being pulled up out of the ground from the filling stations cold underground tank and it becomes heated by the engine in the bike as well as by ambient air temperature. If you filled the gas tank to the very top of the neck the liquid gasoline itself would expand and squirt out after being heated and then gasses would escape until the tank was empty. Exactly how much vapor would escape, I don't know for certain, but place a teapot of a hot burner and check and see how long it takes for the water in the pot to evaporate and you'll get an idea. Do a search online and you will find the stats on gasoline properties and then you can work out yourself how much gasoline vapor would escape through a certain size hole if heated to a certain temperature. Lastly, picture your bike flipping over with you trapped under it and a steady trickle of gasoline is covering your body while your hot bike with live battery is preparing itself to become an inferno. Do you still recommend drilling a hole in the gas cap?

Actually this post was made by Vic so I don't know why it shows skabeeb as the author unless I was signed in as skabeeb when I was fixing a problem he was having.
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#8 08-07-2009, 02:38 PM,
I'm kind of puzzled. I've read this post three times and am wondering..................who recommended drilling a hole in the gas cap?
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#9 08-07-2009, 02:46 PM,
glhonda Wrote:I'm kind of puzzled. I've read this post three times and am wondering..................who recommended drilling a hole in the gas cap?
Actually no one did.
The young fellow Vic quoted in the origanal post asked if he should and the response was a resounding NO.

Then someone posted about a fuel starvation problem because of a malfunctioning cap.
In that case I think it would be OK as a very short term emergency measure only until your new cap arrived.

Ken
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#10 08-07-2009, 03:16 PM,
I agree with Ken and to make it easier than drilling a hole in the cap one could just leave the cap on loose in an emergency situation.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#11 08-07-2009, 05:05 PM,
K Bergen Wrote:Actually no one did.

My point exactly. All this clammer about drilling a hole in the gas cap. From what I read, it looked like everyone agreed it was a bad idea for a fix.
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#12 08-07-2009, 05:23 PM,
Granpah:" I guess Tim's original cap had a check (one way) valve letting air in but blocking back, vapor flow. However, if the materials of which the check valve is made gets degraded over time, or dirt completely blocks the valve then either he needs a NEW cap -- has to drill a small hole for equalizing the inside and outside pressure of the gas tank. "

Granpah was the only one that suggested drilling a hole in the cap but I'm glad we all agree that it's a bad idea.
Ed (Vic) Belanger - 1954-2015
Founder of gl1200goldwings.com

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#13 08-07-2009, 05:36 PM,
Granpah:" I guess Tim's original cap had a check (one way) valve letting air in but blocking back, vapor flow. "


And that's how it works, fuel vapours are directed through the evaporative emission control system and that feeds back into the intake.
Most cars built since the seventies use that system and when you remove the fuel cap you'll hear a slight release of pressure, it's normal.
When you don't hear it that's the time to worry.

Ken

Oops: I screwed up but you know what I mean. :ymblushing:
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#14 08-07-2009, 07:14 PM,
K Bergen Wrote:And that's how it works, fuel vapours are directed through the evaporative emission control system and that feeds back into the intake.
Except our bikes don't have evaporative systems. Only on the California model gl1200. It requires a special gas cap and a recovery chamber. Believe me, you don't want to have to buy one of those suckers.
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#15 08-07-2009, 07:40 PM,


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