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Yesterday I needed to fuel my bike, something I have done numerous times over the last 6000 miles of riding. Now, I do live in the Phoenix, Arizona area, and it was probably around 103 F when this took place. So I put gas in the tank, I only filled to the bottom of the filler neck insert inside the tank. When I left the station all was fine for about an eighth of a mile, and then fuel started pouring from the fuel cap, due I would guess to heat expansion. I slowed down a little and it seemed to subside somewhat. I made a stop, and when I started moving again, the gas started coming out. It seemed like it was worse at low speeds, so I got moving again and it subsided.
The whole point of this isn't so much that it was leaking, but why it was leaking. I had replaced the stock gas cap with a unit from Lowbrow Customs. It is a vented cap, and obviously gas can and does leak out of it. So the question I have, is the stock cap vented or non-vented. I don't seem to be able to find that info in the places I have looked.
I have ordered a Hogworkz flush mount cap, that is suppose to be vented. If you have used this cap, any feedback you have would be helpful. If the system needs a non-vented cap, then I will send this item back as it will probably leak also.
I just recently had same. Flush mount cap... Stop to get gas, pick bike up to leave, gas pours out, not splash... Flows. I kept trying to make sure cap it tight... But I'm guessing the bike is hot, creates fumes/pressure, flows out when it gets to neck.
I have been filling to less than neck, and leaving cap loose. When I leave I will tighten and no more problem. But I did assume it was venting problem and didn't know if it was cap vent or tank vent not doing it's job.
My cap is vented which you can see. I'll have to check if it's plugged.
I just recently had same. Flush mount cap... Stop to get gas, pick bike up to leave, gas pours out, not splash... Flows. I kept trying to make sure cap it tight... But I'm guessing the bike is hot, creates fumes/pressure, flows out when it gets to neck.
I have been filling to less than neck, and leaving cap loose. When I leave I will tighten and no more problem. But I did assume it was venting problem and didn't know if it was cap vent or tank vent not doing it's job.
My cap is vented which you can see. I'll have to check if it's plugged.
What brand of flush cap do you have?
Yes, it flowed out on me also. It seemed to me that when the bike was running it was more pronounced. If the stock caps are non-vented, then I assume running a vented cap is going to be a problem.
so it didn't leak with the original cap? maybe take the old one with you and see if it happens again, I have the HD flush mount and have never had a problem, I fill the tank up too, New Zealand's not as hot as Phoenix though
The tank itself should be vented since at least the Rushmore bikes. Hence the line coming off the tank going to the ground on the right side frame down tube,
The tank itself should be vented since at least the Rushmore bikes. Hence the line coming off the tank going to the ground on the right side frame down tube,
I found this also-
For Harley-Davidson Low Rider S/ST models, the fuel system is equipped with an internal tank vent tube system. Because the motorcycle vents the tank via this dedicated hose, the stock gas cap itself is non-vented
What brand of flush cap do you have?
Yes, it flowed out on me also. It seemed to me that when the bike was running it was more pronounced. If the stock caps are non-vented, then I assume running a vented cap is going to be a problem.
Just some cap off Amazon. Nothing name brand. I didn't HAVE to have a flush mount, I just couldn't stand the rattling/buzzing of the stock one.
The tank itself should be vented since at least the Rushmore bikes. Hence the line coming off the tank going to the ground on the right side frame down tube,
Yes, and you have to disconnect when taking tank off... Which is why I don't get it. So it seems, if I fill the tank up to filler thingy, and put the bike upright, then it's full to neck, and pressure forces fuel out.
Now at first I thought cap was loose, and I was just splashing fuel out ... But I finally saw it and it was no splash... It flowed. A LOT!
And sure I thought something wrong with cap, but the tank is vented, so how the hell is it pressurized? And I never have anything out of tank vent.
I also thought I was filling too full, and backed off a bit. But I've been filling it like that as long as I've had it. Something changed recently.
So back off on fill a bit, and leave gas cap loose to allow venting, no more problem. Tighten down after leaving. Yet the tank is vented, and who cares about this, and it shouldn't happen unless tank vent is cut off somewhere.
The cap should be one way vented in. Most but not all Harleys have a vent hose on the tank that runs down and ends with verticle restricted piece on end. It only allows pressure rise in tank sitting to vent only air.
It resist liquid surge running and coming to a stop.
On California and maybe a few other States, the vent line goes into a carbon canister that has a vacuum line that when the bike runs, purges the canister into the intake .
You have a serious and very dangerous issue with your cap or the vent hose has somehow became mashed closed.
Your cap your ordered may be OK if it says it's OK for your bike. To some, vented and vented in only is the same.
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Vented; Non-vented. Does Anybody Know for Sure?
