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still unsure after reading auxiliary fuel tank threads

kalifornia

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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.
 
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?
 
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.

IMG_5755.jpg


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.

IMG_2534-XL.jpg


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.

IMG_2533-XL.jpg


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.

IMG_6329-XL.jpg


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.

IMG_6324-XL.jpg


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.

IMG_6331-XL.jpg


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.

IMG_2534-XL.jpg

IMG_2526-XL.jpg


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.
IMG_2517-XL.jpg


Ten or so minutes later, nice around town commuter.

IMG_2770-XL.jpg


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
 
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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?
 
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.
 
Dale’s rack release and raises using the stock mechanism. If you get the one with the fuel hole you don’t really need to raise it, however.


Sent from my iPhone using Tapatalk
 
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

IMG_3140.jpgIMG_3141.jpg
 
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?
 
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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-Assemb...i=B07BMVRC25&refRID=04Z6W8RYHMVRWG1ABRQ7&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?
 
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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.

I don't recall the thread but I wouldn't plug the stock tank's vent line under any circumstances. Any fuel remaining in the transfer hose can potentially act exactly like the P trap under your sink. Only instead of preventing sewer gases from wafting into your house, a plugged vent would prevent the build up of explosive gasoline fumes from escaping to either the charcoal canister or atmosphere, depending on the emissions of your bike.

It is also against federal regulations to tamper with the stock fuel emissions control system and if equipped, the evaporative emissions control system.

Grab a flat topped fuel cap like Dave mentioned and just drill a hole in it. I used the stock cap w/large ridge running across it..... What a pain it was to drill!

BTW, I used 4AN sized fittings/hoses and my aux tank drains s-l-o-w. That itty-bitty vent pipe going into the filler neck of the stock tank would probably take even longer to drain. Might not be an issue but something to think about.
 
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OK I understand what you're saying. Correct me if Im wrong, that vent opening can and does do two things. It allow vapors out of the tank should it get hot/while the tank is being filled and it allows air into the tank to replace the fuel being consumed?
 
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Correct me if Im wrong, that vent opening can and does do two things. It allow vapors out of the tank should it get hot/while the tank is being filled and it allows air into the tank to replace the fuel being consumed?
Sounds right...But.....I'm clueless on the engineering behind the design so there might ancillary benefits to other systems on the motorcycle that I'm not aware of (ex: mileage, drivability, durability). Or, it can just simply be a hose that dangles under the motorcycle ;-)

Note that some NCs (depending on where they were sold) also are required to have that vent hose lead to a solenoid that controls an evaporative control valve. The valve injects the fuel vapors back into the intake manifold to be combusted. These motorcycle also have an evaporative canister that is connected to the vent hose to collect and clean the fumes when the motorcycle is just sitting.
 
In the United States, the fuel tank vent line is connected to a charcoal canister that is supposed to prevent gasoline fumes from being released into the environment by capturing them in the charcoal. I believe there is also a line from the charcoal canister to the airbox to help burn the fumes by sucking them into the engine.

That is why they say not to overfill the gas tanks on motorcycles and cars. You run the risk of flooding the charcoal canister through the vent line and there is a possibility of damage to the emissions protections on the vehicle.
I’m not sure it will actually be permanently damaged, but a flooded charcoal canister will absolutely not function correctly to capture fumes until it dries out.

JT
 
Hey Kali, i did read and am familiar with that thread and that guy was successful in using a military type ammo can for his additional fuel capacity. He did tap into the factory tanks fuel "breather/vent" line and used a new breather/vent line out of his ammo can... thus/effectively increasing his fuel capacity and effectively venting the entire system through the new vent in his ammo can. Done properly, as he did, it will work.

As stated before by our esteemed/knowledgeable colleagues, be very careful before modifying your fuel system. Map it out on paper before making any modifications. Use quality/professional fittings & lines etc. I too have been kicking around the idea of adding an additional tank for increased mileage to increase my range for a future attempt at an IBR/SS run.

Later this year when the snow starts flying in my area i will put my NC on a stand/bench and many of its parts are coming off. I really want to get at the factory fuel tank and see if it is possible to hold more fuel. If so, and i deem it cost effective, then i'll have a tank fabricated to fit/maximize the area available and install it. :{)
 
hey rapturee hope you're well. I still havent gotten an nc yet. but my bike is selling this weekend and Ill have room for an nc. Ill have something on my bike, probably a plastic fuel can. Ill send you my # because I'de be up for some crazy distance attempt. But if it turns dark, im following you.
 
roger that, you are welcome anytime! 'Duelin just about has me talked into a newer DCT, ok, not that it would take too much arm twisting haha! The NC is just an amazing machine IMHO, i am so very pleased with mine. If i were to part with it, it would only be fore getting the NC750 in DCT! A guy might as well have a few more CC's and no more clutch to pull for my arthritic left hand(there are days i dream up plans to relocate that stupid clutch handle to the right side). Then i have several good days and reconsider haha. :{)
 
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Thanks for the post Dave, that is a neat system and i like it! I see that it served you well and i've considered a similar setup for my attempt. 170 mile range at that speed just isn't enough for me either and prompted me to consider an alternative source. Yours is simple, easy to use and effective. You posted a great RR documenting that attempt, thank you for sharing it with the rest of us. I'm still trying to fit my first attempt in this season/year. I have a couple of routes planned out, we'll see. :{)
 
Thanks for the post Dave, that is a neat system and i like it! I see that it served you well and i've considered a similar setup for my attempt. 170 mile range at that speed just isn't enough for me either and prompted me to consider an alternative source. Yours is simple, easy to use and effective. You posted a great RR documenting that attempt, thank you for sharing it with the rest of us. I'm still trying to fit my first attempt in this season/year. I have a couple of routes planned out, we'll see. :{)
If your only getting 170 miles out of a tank I'm curious if you've thought of changing sprockets to get better mileage?

Changing just the front sprocket to a 17 tooth my Speedo is off by around 5mph (according to multiple GPS units I've tried) so when my Speedo says I'm going 75mph in actually going 80mph, with that slight change I've been getting 230-240 miles per tank and have never run out (I think I could get 250) that's averaging 75mph-80mph mostly flat freeway elevation 100-400 ft above sea level with various wind conditions, OEM side cases and a 200 pound plus rider

I'm also planning on buying this

LC 2.5 GAL Utility Container https://www.amazon.com/dp/B07NQ2PC1P/ref=cm_sw_r_cp_apa_i_1pozDbDYN5850

And just strapping it to the rear rack for now so I can explore the Sierra mountains east of me without stressing about gas so much
 
Thanks for the post Dave, that is a neat system and i like it! I see that it served you well and i've considered a similar setup for my attempt. 170 mile range at that speed just isn't enough for me either and prompted me to consider an alternative source. Yours is simple, easy to use and effective. You posted a great RR documenting that attempt, thank you for sharing it with the rest of us. I'm still trying to fit my first attempt in this season/year. I have a couple of routes planned out, we'll see. :{)

I've done several SS1000s on NCs using the stock fuel system though extra fuel is always welcome. There is plenty of time in a Saddlesore to make the necessary fuel stops as long as available stops are close enough together and the route is not two lane roads that slow down average speeds. Good luck, we will cheer for you.
 
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