Author Topic: is this right?  (Read 8575 times)

Offline kidsmoke

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is this right?
« on: May 06, 2015, 11:21:38 AM »
rode 120 miles, topped off the tank and almost immediately, parked the bike.
This was followed almost immediately by the strong smell of gas, and then the hiss of fuel as it sputtered on the piping hot headers.

A frantic search led me to find this nipple pissing gas.




i tried removing the cap and standing the bike up, thinking some sort of air/vaccuum thing was happening. stopped. I fired up the motor, and It was then pissing while running. Thinking that wasn't good I turned the bike off. It stopped after what seemed a long time but was probably just a couple of minutes. I let the bike cool in the shade of the garage and it hasn't repeated. I ran it around a bit last weekend and haven't had any issues, nor have I refueled. Was it heat expansion? Just too full? Should neither of the nipples in that photo have a hose of some sort?
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Offline Abbienormal

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Re: is this right?
« Reply #1 on: May 06, 2015, 11:24:26 AM »
I probably can't answer this but I may if I knew what model and year the bike was.
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Offline kidsmoke

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Re: is this right?
« Reply #2 on: May 06, 2015, 11:26:57 AM »
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Offline rocker59

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Re: is this right?
« Reply #3 on: May 06, 2015, 11:38:38 AM »
I'm pretty sure that's the gas tank vent and should have a rubber hose going to the ground.

FWIW, if you top off the fuel tank on a hot motorcycle and immediately put it up, overflow is not uncommon.

If you absolutely want to gas up your bike at the end of a ride, leave some air space in the tank.

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Re: is this right?
« Reply #3 on: May 06, 2015, 11:38:38 AM »

Offline Kev m

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Re: is this right?
« Reply #4 on: May 06, 2015, 11:41:21 AM »
You're talking the red nipple, the one on the tank, not the silver one which provides the atmospheric input to the pressure regulator right?

Yes it's sorta normal. I mean, it's the tank VENT.

It is SUPPOSED to be hooked up to a vent line that ran down to the dual EVAP canisters, through a check valve and/or tip over valve if memory serves.

The trick is that if you remove the canisters (and I DID on my Jackal, even though I've left them in place on everything else) is to leave the valves or AT LEAST the tubing in place, and run the tubing down near the swingarm.

You'll still get some overflow if you fill it up on a hot day (with colder/denser fuel from the underground storage tanks) but at least it will be directed at the ground instead of at the pipes.
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Offline kidsmoke

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Re: is this right?
« Reply #5 on: May 06, 2015, 11:46:50 AM »
yes...red nipple was the culprit, and I understand its one of two vents on the underside of the tank, neither with tubing....but my thought was A) why SO much gas (i didn't fill it more than previous top off's, and B) where's the damn hose?? Haven't lost anything that I'm aware of.

Just confirming normal behavior, hence the title of the thread

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Offline rocker59

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Re: is this right?
« Reply #6 on: May 06, 2015, 11:59:00 AM »
Like Kev said, cool gasoline filling a fuel tank will have some overflow on a warm motorcycle, if left to sit.

Have you never seen puddles under motorcycles at gas stations?  Guys roll in, fill up, then decide to take a break.  The gas expands and runs out the overflow, leaving a puddle under the bike. 
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Offline kidsmoke

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Re: is this right?
« Reply #7 on: May 06, 2015, 12:08:15 PM »
cool. so the answer is a qualified yes.

seen this nipple sans hose before??
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Offline rocker59

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Re: is this right?
« Reply #8 on: May 06, 2015, 12:14:14 PM »
My guess is someone, at some point, had the fuel tank off and neglected to hook the hose back up.

That, or someone completely removed it when ditching the Evap Canister setup.

If it was me, next time the tank was off, I'd run a hose down the backbone of the frame and down to towards the ground at the back of the transmission.
Michael T.
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Offline sib

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Re: is this right?
« Reply #9 on: May 06, 2015, 12:26:55 PM »
Before people start "improving" the fuel systems on their bikes, they function well, as they're designed to.  There is one hose that goes from the tank to the bottom of the bike.  This one is NOT to vent the tank, but rather to get rid of any fluid that gets into the gutter space around the filler opening.  This includes rain water, but also excess fuel when you overfill the tank or if you splash some fuel into the gutter while filling the tank.  If the hose is missing, the fuel instead dribbles onto the bike.  There's a second hose that runs to a special valve, and then another hose from the valve to the evaporation control carbon canister.  The valve has two important functions: 1) it prevents water vapor in the air from freely diffusing into the fuel tank, which is especially important with hygroscopic ethanol-containing fuel and humid climates; 2) it prevents fuel from gushing out onto the hot engine and exhaust pipes if the bike goes down or if the fuel in a full tank expends on heating.  People who ignorantly "improve" their bikes by removing these hoses should only blame themselves when fuel is expelled unexpectedly.
« Last Edit: May 06, 2015, 12:27:21 PM by sib »
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Offline Kiwi_Roy

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Re: is this right?
« Reply #10 on: May 06, 2015, 01:16:03 PM »
Sib is partly right, the fuel gutter opening is further back though, directly under the rear of the filler cap.
The one in the picture is the one that has the breather conservation valve attached. I think I have a spare valve if you need it.

The fuel gutter drain can be a problem if it blocks with rust (both mine were blocked) the gutter fills up with water waiting there until next time you open the cap, the water runs into the tank un-noticed causing it to rust badly.
EVs and Jackals share this problem, when you get a chance dribble a little light oil into the gutter and make sure it disappears down the hole.
« Last Edit: May 06, 2015, 01:43:29 PM by Kiwi_Roy »
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Offline Kiwi_Roy

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Re: is this right?
« Reply #11 on: May 06, 2015, 01:41:30 PM »
I had a related problem with my California II tank, I'm sure the same style is used on many bikes of the era.
If I filled it too full the air pressure would force fuel up the filler spout and it would run all over the tank.
I can't think why they make this spout so long.

I fixed it by drilling a tiny hole in the side of the filler spout, this lets it breath without gushing fuel.
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Offline mtiberio

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Re: is this right?
« Reply #12 on: May 06, 2015, 02:16:02 PM »
A hole like that also allows you to over fill the tank, leaving a greatly reduced air space.
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Offline rodekyll

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Re: is this right?
« Reply #13 on: May 06, 2015, 02:25:15 PM »
The potseed tank has a vented lid.  The tube is there to keep fuel from splashing into the vent while sloshing through the twisties.  I'm not sure about the need for any particular length.  I recently cut up a couple of loop tanks.  The tubes were about 10mm different in length.  One had that hole drilled in it.

I drill that hole in all my potseed tanks -- on the high (right) side of the tube.  I fill faster, cleaner, and more completely than without it.  If I fill on the centerstand (or dead-upright) I MUST run the first quart or so out before parking on the sidestand.  If I fill and then park on the sidestand away from the pumps I'll burp all over my paint.  So I do my potty, coffee, BS'ing, and then fill and go.

I used to preach against removing the evap system for this (among other) reasons.  I don't anymore.  If a guy burns down his bike because the rebel in him made him remove the evap, he had it coming.  Really -- you can more colorfully show your disdain for the gubbmt by wearing your pants around your knees.

Offline 1Sourdough

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Re: is this right?
« Reply #14 on: May 06, 2015, 03:45:52 PM »
A hole like that also allows you to over fill the tank, leaving a greatly reduced air space.

OK; there is a point I have pondered... Many years ago I took a hammer and nail, and put a hole in that spacer inside the filler on my Convert.  It was recommended by someone or other as a way to get an additional 25 or so miles per tank of gas.  I used the nail because he said the arcing of a drill motor could very well start something ablaze. 

So, before taking the action I considered that bit about the "greatly reduced air space", and decided that since fuel expansion had already been shown on that machine to quickly fill the spacer tube and overflow, it wasn't a serious concern since it was going to overflow either way:

Leave the 'air gap' tube as original and expanding fuel quickly fills it and gushes out the vented gascap, or defeat it by putting a hole in it and the fuel gushes out when it expands... Any thoughts about that?
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Offline Kiwi_Roy

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Re: is this right?
« Reply #15 on: May 06, 2015, 03:46:36 PM »
A hole like that also allows you to over fill the tank, leaving a greatly reduced air space.
You could overfill but it would take time as the air has to vent at the same time. Its so easy to fill the tank to a point where the tube just dips into fuel, if you leave it in the sun or even a cool garage it forces up the tube spilling over the tank.
I used the smallest drill I could find. The hard part is to get the drill started on an angle a good deep center-punch mark required.
BTW I used a hand drill rather than a sparking electric to drill the hole.

1Sourdough - the fuel doesn't expand it's the gas trapped above the fuel that goes up in pressure to blow the fuel up the spout.
« Last Edit: May 06, 2015, 03:49:41 PM by Kiwi_Roy »
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Offline kidsmoke

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Re: is this right?
« Reply #16 on: May 06, 2015, 03:52:50 PM »
Its so easy to fill the tank to a point where the tube just dips into fuel, if you leave it in the sun or even a cool garage it forces up the tube spilling over the tank.

I suspect this is my case. I can also see the rear vent, What you're calling the gutter vent, and it does not have hose on it either. I did have some 12v work done on this bike recently and I'm thinking now they may not have replaced hoses for these vents. This was the first top off since getting it back and the first time I've experienced this overflow....althoug h....almost all of my riding on this bike previously was in much cooler conditions, also.

Thanks for the tank/fuel/physics lessons. All good info.

particularly that note about the non sparking drill. Who knew??
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Offline lorazepam

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Re: is this right?
« Reply #17 on: May 06, 2015, 03:54:31 PM »
Taking the evap crap off make the tank just like many many bikes I have had over the years. When the check valve, or the carbon canister plugs up, the bike will be dead in the water.  I have never had a bike burn because of fuel leaking out of a vent tube.

Offline Kev m

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Re: Re: is this right?
« Reply #18 on: May 06, 2015, 06:28:12 PM »
I said it was sorta normal because it depends on how full the tank is, and how much of a temperature difference there is, and how soon you park it.... Not to mention whether or not there is a hose there.

I'd add a hose a route it to the ground.

.
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Offline Kev m

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Re: is this right?
« Reply #19 on: May 06, 2015, 06:42:39 PM »
On reading the rest of the thread I feel I should comment.

The Jackal was the only bike I every bothered to remove the EVAP system from, partially because the hoses were already cracking, but largely because it utilized not one, but TWO large (a couple of pounds each) metal charcoal canisters and like 8 feet of tubing. It was ugly and ridiculous.

I left the vent hose with the two check valves, but found that it still seemed to stink up the garage sometimes, and occasionally pissed fuel on the ground after a full up/park situation.

Fwiw, all the bikes I've owned WITHOUT EVAP systems never did that (pissed or stunk), presumably because the used a check valve or partially pressurized vent system, not a wide open one which can occur if the just remove the EVAP system and valves.

Although I left the valves in place, they were notorious for failing which I presume had happened to mine.

With regards to leaving the systems alone. They've been on cars for decades now and I can't recall EVER hearing of even a single case where a plugged EVAP  canister ever caused a no start or even a stall. Much ado about nothing... Both our V7 and Duc have the systems intact. The V7 EVAP canister is even happy.. SEE

 
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Offline sib

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Re: is this right?
« Reply #20 on: May 07, 2015, 07:20:06 AM »
Taking the evap crap off make the tank just like many many bikes I have had over the years. When the check valve, or the carbon canister plugs up, the bike will be dead in the water.  I have never had a bike burn because of fuel leaking out of a vent tube.

To each his/her own.  I've never had a bike become dead in the water because of a plug in the check valve or canister.

I don't know where the air you breath comes from, but I get mine from the atmosphere the rest of us share with our machines.  When I use a swimming pool, I try not to piss in the water.  Others may enjoy needlessly polluting shared resources.
« Last Edit: May 07, 2015, 07:25:29 AM by sib »
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Offline Wayne Orwig

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Re: is this right?
« Reply #21 on: May 07, 2015, 07:31:29 AM »
I had a related problem with my California II tank, I'm sure the same style is used on many bikes of the era.
If I filled it too full the air pressure would force fuel up the filler spout and it would run all over the tank.
I can't think why they make this spout so long.

I fixed it by drilling a tiny hole in the side of the filler spout, this lets it breath without gushing fuel.

I did the exact same thing to my 1994. If you filled it to the neck, it could expand and gush out the gas cap.
I did NOT, and WOULD NOT do the same to my 2004 EV.

The difference is that the 1994 had the vent IN THE GAS CAP. When it expanded, it had to go up the neck and out the cap. So the little pin hole that I drilled in there helped to balance things out and help to use that wasted air space.
On the 2004, the gas cap is sealed. The vent is in the air space in the top of the tank. So when it expands, it expands into the wasted air space outside the neck. And the tank vent line vents the fumes, or the gasoline if you overfill it.
« Last Edit: May 07, 2015, 10:05:44 AM by Wayne Orwig »
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Offline Kiwi_Roy

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Re: is this right?
« Reply #22 on: May 07, 2015, 09:21:52 AM »
The fuel doesn't expand, not very much at least, it's the trapped vapour that causes the problem.


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Offline Kev m

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Re: is this right?
« Reply #23 on: May 07, 2015, 09:50:33 AM »
The fuel doesn't expand, not very much at least, it's the trapped vapour that causes the problem.

Does that explain the expansion chambers found in modern automotive fuel tanks?

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Offline Steve Scott

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Re: is this right?
« Reply #24 on: May 07, 2015, 12:47:30 PM »
I'm actually surprised to hear that there are any Cali's of that vintage with the evap system still intact. Mine was pissing fuel out of the charcoal canister drains within a few weeks of purchase, and the subsequently fuel-contaminated and sticky check valve stuck closed soon after causing the dreaded "tank-suck". There were a lot of leaky fuel tanks out there with stress-cracks underneath if that situation wasn't corrected in time.

My evap-system, removed when the bike was only a couple months old and like new except for the spots where the bottoms of the canisters hit the swingarm  >:( is still in a box in the shed. My plan is to wait until the odometer rolls over a second time and then put that stuff back on and try to sell the bike as an unmolested, low-mileage "survivor". ;D

Be thankful that your poorly designed evap system was "molested" before the tank cracked, and next time the tank is off run a line down by the swingarm pivot. I put a fine sintered-brass filter at the end of that hose to keep air / fuel-vapor transfer to a minimum, and also to keep the critters out. Yellow Sac spiders love fuel vapors and will plug open lines with their webs.
« Last Edit: May 07, 2015, 12:48:57 PM by Steve Scott »
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