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Thread: still unsure after reading auxiliary fuel tank threads

  1. #1
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    still unsure after reading auxiliary fuel tank threads

    I've read all the threads I can find and none of them clarified to my understanding what works and what doesn't. So let me ask my question this way. If I place a vented container of fuel on the passenger seat and stick a hose down to the bottom of that container, and run that hose to the fitting by the oem fuel cap will that work? Can anyone describe or post clear pictures of the most simplified setup proven to work? I thank you.

  2. #2
    Senior Member HarveyM's Avatar
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    No. My gas tank has an overflow/vent tube, so the gas tank doesn't develop vacuum to suck fuel out of an Aux tank. Even if you sealed the tank, what happens if you drop the bike? Will your setup leak fuel over the hot parts?

  3. #3
    Senior Member still unsure after reading auxiliary fuel tank threads ld_rider's Avatar
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    Quote Originally Posted by kalifornia View Post
    So let me ask my question this way. If I place a vented container of fuel on the passenger seat and stick a hose down to the bottom of that container, and run that hose to the fitting by the oem fuel cap will that work?
    No.


    My system has been proven to work for about 200,000 miles on two different motorcycles. It has also pass technical inspection at various long distance riding events and survived a high-speed, end over end interstate crash that obliterated the motorcycle but with no damage to the fuel tank, plumbing, or valve.

    Correction: This isn't by any means "my system" but is the system that was recommended to me. I'm not nearly smart enough to figure all this out myself ;-)

    Why it works: No modification to the factory fuel lines or emissions/venting system. Relatively inexpensive (sorta). Easy to source parts. Aux fuel container is protected in event of a crash. Is completely separate from stock fueling system and can be removed in minutes, even if the aux tank is full of fuel. Uses gravity to work, which is pretty reliable ;-)

    Your factory fuel tank is vented and needs to remain vented. Same with any aux fuel container. As fuel heats, it will expand in volume. Sometimes remarkably so. It isn't uncommon to wander around a parking lot under a mid afternoon sun and see fuel dribbling out of the overflow vents on the aux fuel tanks that are full. Your stock fuel tank will do the same if it is full enough and the temps are high enough.

    How it works: When my low fuel light starts flashing while riding, I can reach behind me and turn a valve that allows fuel from the aux tank to gravity feed into the main tank. Since the aux tank has a smaller capacity than the main tank AND the fuel flow rate (due to small diameter of the fuel hose) is slow, I have no worries about "overfilling" the main tank. It takes about 15 or 20 minutes to drain the 3+ gallons from the aux to the main tank.

    Once all the fuel is transferred, it is time to reach back and shut the valve off. The bike now has a full tank of gas without even stopping. Nice!

    Here are a few pics to give you an idea what I'm talking about.

    I removed the passenger seat and replaced it with this platform. This is where the aux tank will be mounted.



    The tank is an off the shelf 3.5 gallon diamond plate aluminum with a bottom, center outlet and a vent outlet on the filler neck. The tank included mounting straps which are bolted to the aluminum platform and hold the tank securely in place. It is important if you are using a platform like this (mounts exactly like the passenger seat did) that you carefully measure and make sure you aren't drilling topside holes in the platform that will end up interfering with the stock passenger seat mounts (since those mounts are needed to bolt the platform to the bike).

    In this picture you can also see the 1/4 turn Motion Pro fuel valve that I drilled and mounted on the stock factory fuel cap. This is the valve that I reach behind me to turn on when the low fuel light starts flashing. The clear, fuel rated hose you see has enough extra length so that I can remove the cap to refill the stock tank. I cannot simply leave the valve open and fill the stock tank by fueling the aux tank. Remember, it would take about 15 or 20 minutes for the fuel to transfer.



    I've also run the tank with a quick disconnect valve (white, plastic thing) that you can see here. This particular valve will stop the flow of fuel even if the aux tank is full. That allows me to remove the tank without worrying what to do with the 3 gallons of gasoline inside. If I push down the silver tab on the female end, it will release from the male end and keep all the fuel from running out the hose. It makes unscrewing the stock cap easier without a hose to contend with.



    One thing that concerned me was what if there was a leak in the hose "before" the fuel got to this shutoff valve on the fuel cap? There would be no way to stop it and 3 gallons of fuel would pour out. I have since added a shut off valve directly on the bottom of the tank. Think of it as an emergency shutoff valve. You absolutely need a method to stop fuel flow if there is a hose leak.



    This photo shows the aux fuel tank venting hose. Again, both tanks need ventilation since they are essentially two separate tanks. The black hose connected to the filler neck runs down the side of the bike behind my panniers. If I typically filled the aux tank to capacity (3.5 gallons) I would use a catch can at the bottom of the hose (a budwiser can works fine) so the expanding fuel doesn't run all over the ground. I never fill it that much since the stock 3.7 and my typical fill of 3 gal on the aux gives me outstanding range with the NC's miserly fuel consumption.



    You can see the venting hose in this photo. Make sure ALL hoses are fuel rated otherwise they will crumble in no time. The GPS that controls my onboard automatic chain oiler had departed the motorcycle and I ended up having to do an emergency duct tape repair. That is the mess you see on the topside of the aux tank.



    Crash protection. I have no desire to turn into a huge orange fireball simply because I low sided or otherwise dropped the bike and generated a spark. If you look closely, you can tell that the fuel tank is fully inside the envelope of the motorcycle. In other words, if I lay this bike down the tank will (likely) not be able to contact the ground. You can see how narrow the tank is in these two pics and the protection around it, making it almost impossible to contact the roadway.




    I every so often go on really long rides and have my motorcycle outfitted for that purpose. But, I use it mostly to commute and just run around town. I've set it up so that I can transform from a full-on long distance motorcycle to an around town commuter in less than 10 minutes.

    Full up long distance touring mode.


    Ten or so minutes later, nice around town commuter.



    Things I would change: I purchased another stock, factory fuel tank. I plan on having a fuel bung welded to it and then connect the aux tank to that fuel bung rather than the stock fuel cap for a cleaner install. The Motion Pro fuel valves are junk. JUNK! I've gone through at least two of them and after a year they leaked. Should use something like an Earl's ($50) rather than the cheap Motion Pro. The quick disconnects are plastic. Not lovin' them. No issues but rather use aluminum for peace of mind. You can't see any of this plumbing while riding and would hate to find out the hard way I had a 3 gallons of fuel leaking all over the electronics under the seat :-(

    EDIT: This is a great writeup of how to do an aux fuel tank Extreme Farkling Deux : Auxiliary Fuel Tank
    Last edited by ld_rider; 24th August 2019 at 11:35.
    Rob in New England
    IBA# 540

  4. #4
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    That's a cool setup ^^^

    Sent from my SM-G930V using Tapatalk

  5. #5
    Senior Member still unsure after reading auxiliary fuel tank threads
    still unsure after reading auxiliary fuel tank threads
    Red Rider's Avatar
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    Very slick indeed and well thought out.

    One question - not related to the tank: does that Dale’s Rack operate just like the stock pillion seat; raise up, utilize the release lever, etc? Or is it bolted down and locked in place?


    Iím supposed to respect my elders, but itís getting harder and harder for me to find one now ..

  6. #6
    Senior Member still unsure after reading auxiliary fuel tank threads ld_rider's Avatar
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    Quote Originally Posted by Red Rider View Post
    One question - not related to the tank: does that Dale’s Rack operate just like the stock pillion seat; raise up, utilize the release lever, etc? Or is it bolted down and locked in place?
    It operates exactly like the stock pillion seat, utilizing the stock mounting screws and release lever. It can raise up just like the stock pillion. I like that feature since under the seat I have some electronics wired up.

    Some tech inspectors will grab the tank and try to rock the bike back and forth. It the tank won't move, but the plate it is mounted to will sometime show some "give". Depending on the inspector, I will add a couple of large stainless hose clamps through the slots on the side of the rack and clamp it to the passenger hand holds.
    Rob in New England
    IBA# 540

  7. #7
    Senior Member still unsure after reading auxiliary fuel tank threads GregC's Avatar
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    Daleís rack release and raises using the stock mechanism. If you get the one with the fuel hole you donít really need to raise it, however.


    Sent from my iPhone using Tapatalk

  8. #8
    Senior Member still unsure after reading auxiliary fuel tank threads dduelin's Avatar
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    I've used this simple low budget system to add 1.6 gallons of fuel. The tank is made by Acerbis for dirt bikes and has a fuel cutoff valve on a bottom corner. The aux tank is vented to the atmosphere with the purple hose which is led down to near the license plate. Like Rob posted above, when the fuel gauge drops to 2 bars or less I reach around to the left rear corner of the Acerbis and open the petcock. The gas drains through a Honda gas cap from a Honda scooter directly into the OEM tank. This style cap has a flat top that is easy to drill the hole to receive the 90 degree hose barb fitting. The hose from aux tank to the fuel cap is long enough to easily remove the fuel cap and refill the main tank. I would like the petcock on a front corner but I needed the Acerbis fuel fill on the right side so I could completely fill it when the bike is on the side stand. The base is cut from plywood and replaces the pillion seat using the same three bolts as OEM. This was the last of several versions I tested in preparation for a Bun Burner Gold (1500 miles in 24 hours). I felt I needed enough fuel to make comfortable 250 mile legs between gas stops. I did not complete 1500 and settled for a Saddle Sore 1000 (a multi-vehicle accident on I-75 brought me to a halt at 870 miles in. I still want to complete a BBG on the NC and will try again one day.

    Aside from the three fixing bolts for the pillion seat and removing the OEM gas cap the bike remains stock.

    50 MPG at 80 MPH Bun Burner Gold | Long Distance Riders | ST-Owners.com

    still unsure after reading auxiliary fuel tank threads-img_3140-jpgstill unsure after reading auxiliary fuel tank threads-img_3141-jpg
    Dave

    GL1800
    NC700XD




  9. #9
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    ld_rider did you ever see the tank thread where the guy was using ammo cans as fuel cells? I ask because it seems he was having success filling the oem tank via the vent line by the oem filler. The pictures were unclear to me however. and thanks Dave, do you agree that filling the tank through the vent line does not work?
    Last edited by kalifornia; 24th August 2019 at 14:35.

  10. #10
    Senior Member melensdad's Avatar
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    I was thinking of mounting one of these, painted black, to a "Dale's Rack" as an aux fuel tank. Amazon link => https://www.amazon.com/Woniu-Assembl...RWG1ABRQ7&th=1

    I don't like the look of a big round cylinder mounted in the back. Cylinder fuel tanks are functional for fuel but I'd think something with a bit less capacity that has a nearly flat top, would allow me to more easily strap a duffle bag on top for travel. I looked at 1.5 to 2.5 rectangular tanks.

    I don't see the need for an Aux fuel during normal riding around home as gas stations are plentiful.

    On our trip into Canada along the north shore of Lake Superior and Lake Huron took along 2 6-liter Desert Fox fuel bladders but didn't ever fill either of them. Every time I refueled I simply asked locals how far it was to the next place to buy fuel. I don't think I ever got below 1/3rd of a tank while on the trip.

    Anyone want to buy a Desert Fox 6 liter fuel bladder?
    Last edited by melensdad; 24th August 2019 at 15:24.

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