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Author Topic: Gas leaking from under the cap  (Read 2370 times)

hillntx

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Gas leaking from under the cap
« on: April 19, 2012, 12:32:55 PM »
I did a search on the forum but didn't find anything.  After riding my C-5, I'll find small lines of gas running down the tank from under the gas cap.  I'm guessing the cap vent is clogged.  Any clues on this one?  I want to get this fixed before it ruins the paint on the tank.  Thanks.

GA-DK

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Re: Gas leaking from under the cap
« Reply #1 on: April 19, 2012, 12:56:58 PM »
I had same concern with my G5.  Pressing on cap showed gasket was not tight.  I put a fairly thick O-ring under the gasket on cap.  This pressed the center of the gasket away from cap forming a bit of a cone shape that sealed better.  GA-DK

Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #2 on: April 19, 2012, 01:17:18 PM »
I cut a small ring from thin cork gasket material and laid it right on top of the original gasket.  No problems since.

Scott

WillW

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Re: Gas leaking from under the cap
« Reply #3 on: April 19, 2012, 02:24:52 PM »
+ 1 for cork.
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Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #4 on: April 19, 2012, 04:58:53 PM »
I think I stole the idea from Will.  ;D

Pauly

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Re: Gas leaking from under the cap
« Reply #5 on: April 19, 2012, 05:16:08 PM »
I had this happen as well last week with my G5. i rode around on some errands, got home and filled the tank from a  can in the shed, the gas i put in was cold, it was a cold morning, by the time i left for work it was running down the side of the tank. i figured it was just the fuel expanding as it heated up, am i correct here or is there another cause?

also brings up another question, and sorry if i'm hijacking the post, I like to figure my fuel economy, how do i fill a motorcycle tank to the same level everytime?
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Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #6 on: April 19, 2012, 05:20:05 PM »
It was more likely just the usual sloshing around of fuel in the tank coupled with a less than perfect seal.  No expansion required to explain this.

Scott

WillW

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Re: Gas leaking from under the cap
« Reply #7 on: April 19, 2012, 05:52:31 PM »
"how do i fill a motorcycle tank to the same level everytime?"

 Here's a tip which always works for me -
 Put the nozzle in the tank and squeeze the trigger  -  
 When the tank is full, stop squeezing.  
 Repeat next time....  ;)
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singhg5

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Re: Gas leaking from under the cap
« Reply #8 on: April 19, 2012, 05:54:14 PM »
I did a search on the forum but didn't find anything.  After riding my C-5, I'll find small lines of gas running down the tank from under the gas cap.  I'm guessing the cap vent is clogged.  Any clues on this one?  I want to get this fixed before it ruins the paint on the tank.  Thanks.

I had used O-rings underneath rubber seal of gas tank cap and no leaks since then.  Pictures and details under thread "New G5 Owner Minor Problems Fixed" that was started by GA-DK.

http://www.enfieldmotorcycles.com/forum/index.php/topic,9250.0/all.html

« Last Edit: April 19, 2012, 05:58:31 PM by singhg5 »
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Desi Bike

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Re: Gas leaking from under the cap
« Reply #9 on: April 19, 2012, 08:00:07 PM »
When you press down on the cap when done filling, it should click twice to seal. Took me a few times to get that sorted out, if only one click it would leak. I'm guessing I was only engaging one side of the latch mechanism.
میں نہیں چاہتا کہ ایک اچار
میں صرف اپنی موٹر سائیکل پر سوار کرنا چاہتے ہیں

barenekd

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Re: Gas leaking from under the cap
« Reply #10 on: April 19, 2012, 10:54:54 PM »
Quote
also brings up another question, and sorry if i'm hijacking the post, I like to figure my fuel economy, how do i fill a motorcycle tank to the same level every time?

Put it on the center stand. Stick the nozzle in about a 1/4" and fill it until it shuts off. The gas should be veerry (sic) close to the filler hole. Try to avoid running it over, I usually have very little overrun, if any. then you  get to see what the little tube is for. It's a drain tube for that section where the cap goes. Try to park you bike on the center stand until you've burn at a little gas out. I have, on a rare occasion, had some gas come out of that drain tube.

Speaking of gas, I did a 100 miler today out to the RE shop, and when I got back home I filled it with 204 miles on this tank. It worked out to 71 mph. My average for the  last 1900 miles has been 69 mpg. 

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singhg5

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Re: Gas leaking from under the cap
« Reply #11 on: April 20, 2012, 04:06:19 AM »
I like to figure my fuel economy, how do i fill a motorcycle tank to the same level everytime?

When you open the tank gas cap and look straight down through it, there is a longitudinally running mid rib (frame bar).  If gas level covers the midrib completely, it is too much and gas will come out when bike leans, or rides over bumps on the road.

While filling gas, I keep looking into the hole and as the level just touches the midrib close to me (rider), I stop so that there is a enough air space above the gas.  The front portion of midrib is above gas level.

PS - It is easy to scratch the paint off the midrib by hitting gas pump nozzle (as I have done clearly seen in picture below), so keep the nozzle at an angle so that it passes on the side of mid rib.
« Last Edit: April 20, 2012, 04:12:57 AM by singhg5 »
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GlennF

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Re: Gas leaking from under the cap
« Reply #12 on: April 20, 2012, 04:09:49 AM »
Well with my B5 on its side, leaning on the front crash bar,  gas absolutely pours out the gas tap.

Ice

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Re: Gas leaking from under the cap
« Reply #13 on: April 20, 2012, 04:54:06 AM »
I lay my Bullet on the side too.
 
 Its the easiest way for me to get the rear wheel out for flat repair due to the panniers on my military.

 Draining the fuel tank into a gas can saves the paint and fuel. If a body does not like packing rigid fuel cans, there is the folding itza can. They take up very little space when stowed.

http://www.itzagascan.com/
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WillW

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Re: Gas leaking from under the cap
« Reply #14 on: April 20, 2012, 07:02:56 AM »
With the cork gasket in place, mine now never leaks a drop, even brim full and hammering round the twisties.  
2mm cork ring, about half inch width, greased initially, just laid over the hole rim. It soon takes on the shape and has stayed in place ever since. You can feel the cap is closing tighter with it in place.
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Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #15 on: April 20, 2012, 07:05:43 AM »
+1, not a drop.

hillntx

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Re: Gas leaking from under the cap
« Reply #16 on: April 20, 2012, 09:55:34 AM »
Where do you find the cork gaskets?

WillW

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Re: Gas leaking from under the cap
« Reply #17 on: April 20, 2012, 12:31:19 PM »
You have to make your own. 2mm cork sheet from a craft supplier.
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Lwt Big Cheese

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Re: Gas leaking from under the cap
« Reply #18 on: April 20, 2012, 12:52:48 PM »
A petrol cap gasket is another item I don't have!

And yes it does leak.

And an MOT failure. Or so I'm told by the tester when he handed me a pass certificate for 20.

 ;).
No warranty implied or given.
Packed in a protective atmosphere.
May contain nuts.

barenekd

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Re: Gas leaking from under the cap
« Reply #19 on: April 20, 2012, 03:58:00 PM »
The screw on gas caps (actually Triumph caps) the California bikes have seal quite tightly. Usually they don't leak in any position.
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idk

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Re: Gas leaking from under the cap
« Reply #20 on: April 21, 2012, 05:21:28 PM »
The cork gasket looks like a good idea. Do you need to soak them?  ::)
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Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #21 on: April 21, 2012, 05:31:17 PM »
The local auto shop should have sheets if fuel resistant cork gasket sheet for a modest price.  Cut to size, no presoak required.

Scott

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Re: Gas leaking from under the cap
« Reply #22 on: April 21, 2012, 06:09:43 PM »
All petrol caps EXCEPT the CA screw on caps are vented at the cap to allow fuel flow.
This may or may not be part of what some of you are seeing. The CA caps are sealed to prevent HC from escaping from the tanks. CA is the only place in the world with this requirement and I am surprised. These tanks are vented into a canister with activated charcoal in them. The charcoal absorbs the vapors. When the bike runs it draws a small amount of air through the canister which purges it. There are no negative performance problems with it. They look unsightly but  that can be improved upon. For my money it is a good device.

singhg5

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Re: Gas leaking from under the cap
« Reply #23 on: April 21, 2012, 06:56:35 PM »
Some riders had mentioned that their Cork Gaskets swell up or became mushy.  Just beware to find the right material.

 ---------------------------------------------------------------------------
This is from an old Post "Do it yourself Gas Cap Gasket"
bullethead63
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Re: Do it yourself Gas Cap Gasket (or Petrol Cap, if you wanna be fancy)
Reply #10 on: November 04, 2010, 10:18:11 AM
--------------------------------------------------------------------------------
After about a week,my new gasket has gotten a little mushy,and swollen...if you're going to use one of these for a petrol tank cap,keep a spare in your tool box,and switch them out with every fill up...that's what I had to do this morning...

walken4life
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Re: Do it yourself Gas Cap Gasket (or Petrol Cap, if you wanna be fancy)
Reply #11 on: November 05, 2010, 08:40:25 AM
--------------------------------------------------------------------------------
That's sad.  Mine seemed ok last fillup but I will check it again when I do the final fill up before winter storage in the next few days.  Thanks for the update.
Last Edit: November 14, 2010, 08:02:45 AM by walken4life

Updates:
My home-made gasket from above swelled a bit .

Decided to try making another gasket with a new material.
« Last Edit: April 21, 2012, 07:04:18 PM by singhg5 »
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Ducati Scotty

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Re: Gas leaking from under the cap
« Reply #24 on: April 21, 2012, 07:29:47 PM »
+1.  That's why you should look for fuel resistant cork gasket material at an auto shop, not craft supply stuff.  A whole roll cost me about $6 I think.  Same goes for the o-ring solution, fuel resistant or it will turn to mush.

Scott

singhg5

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Re: Gas leaking from under the cap
« Reply #25 on: April 21, 2012, 08:39:50 PM »
Same goes for the o-ring solution, fuel resistant or it will turn to mush.

The stability of o-rings against water, salt, gasoline, oils and temperature depends on the material used to make them as shown in the chart below.
« Last Edit: April 21, 2012, 08:44:23 PM by singhg5 »
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WillW

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Re: Gas leaking from under the cap
« Reply #26 on: April 21, 2012, 08:51:24 PM »
I use plain old 2mm cork sheet which I buy in bulk (for my business) from the sawmill. It works fine. I did grease it at first, but only the once, and it's still good after a year or so. Perhaps it just happens to be gasket grade - it's fairly dense. I have seen some poorer quality stuff around, so I guess that'll be the craft shop stuff.
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Arizoni

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Re: Gas leaking from under the cap
« Reply #27 on: April 21, 2012, 09:48:05 PM »
Singhg5
The chart in your post is excellent!

A few words about some of the elastomers mentioned in it if I may.

Although some of the colors of these materials are the same, the colors can indicate if you've got the right material for others.
There are no hard and fast rules about these colors so use them as a general guide.

For instance, Silicone, which is very poor with gasoline is usually orange.
Fluoro-silicone, which is excellent with gasoline is usually blue
European Viton is usually green but American Viton is usually brown.
Buna-N (Nitrile) is often gray
Neoprene is usually black
Color Kalrez (Perfluoroelastomer) EXPENSIVE.  It is so expensive that we used it in jet engines only when nothing else would do.
« Last Edit: April 21, 2012, 09:50:09 PM by Arizoni »
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Rich Mintz

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Re: Gas leaking from under the cap
« Reply #28 on: February 08, 2013, 09:22:21 PM »
On my 2010 Bullet C5 (with under 1000 miles), I smell gas fumes more often than I anticipated.

And I had this happen: I filled the tank at night in cold winter weather, then parked the bike on the side stand in a warm garage. Overnight, due to expansion, gas dribbled over the side onto the floor.

I did the math http://richmintz.com/2013/01/in-which-i-almost-blow-up-a-square-block-of-lower-manhattan/ and it looks like 3 gallons of gas can expand on the order of 30 cubic inches with that kind of temperature rise -- that seems implausible but even if that's 3X the real answer, it still explains where the gas came from. Even with a tight seal, I would have had leakage, and I know empirically that I don't have a tight seal.
 
Since then, in the warm garage I always park on the center stand. And I ordered a roll of "cork gasket material" from an Amazon vendor, which came last night -- when the snow clears, I'll cut a ring of it out and try it in the tank.

singhg5

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Re: Gas leaking from under the cap
« Reply #29 on: February 08, 2013, 10:15:41 PM »
Made cork gasket and it helped a lot -

http://www.youtube.com/watch?v=4qtAOoKsvq8
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Ragmas

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Re: Gas leaking from under the cap
« Reply #30 on: February 09, 2013, 02:43:12 AM »
I took a bit of fuel line and cut it unto a strip about a 1/4" by 1/4" and stuffed it beneath the gas cap rubber much like the rubber o ring.  Not a drip since.

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Royalista

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Re: Gas leaking from under the cap
« Reply #31 on: February 09, 2013, 05:53:12 PM »
And as stated before never fill the tank or store the bike on the sidestand. Every drop spilled is money not ridden and vicious looks from greenlings.

I find it inconvenient and a bit absurd not to fill the tank to the brim. What is that place otherwise for but to fuel more miles? Filling the tank when on the side stand will take 100 kms from your range, that hurts.

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Gypsyjon

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Re: Gas leaking from under the cap
« Reply #32 on: February 10, 2013, 12:30:33 AM »
Mr. Singh, you are amazing!!! 


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