Tour Tank Setup

[davesax36]

There's no canister on my bike. I'm pretty sure that's only on the California bikes. The tip-over is a one-way plastic valve that will let fuel pass under normal conditions, but stops when tipped past a certain angle. This is to keep the whole tank from draining out in the event of a crash.

This is where I still have questions about the seal strength of the stock cap, but let's not open that can of worms until an actual expert shows up here. I'm just going to try not to crash, so I don't have to test any of that stuff.

 

[Falaholic]

I cut 14 to insert my T-fitting because it's where the fuel comes out of the tank and does a U-turn towards the filter.

By feeding at 14, you are fueling the main tank, and fueling the engine?
If you have the main tank's vent tube blocked off, to prevent over fueling/spilling. How is the main tank venting when it is being fed by the AUX tank?

 

[Falaholic]

There's no canister on my bike. I'm pretty sure that's only on the California bikes. The tip-over is a one-way plastic valve that will let fuel pass under normal conditions, but stops when tipped past a certain angle. This is to keep the whole tank from draining out in the event of a crash.

Ah, so no canister, then there should be only one line...leading to the atmosphere.

Curious though, the canister has two lines, I can only assume that one line leads to the atmosphere, but where would the second line lead to?

 

[davesax36]

One is for some emissions filter. My bike has one line leading to atmosphere that's secured to the front of the battery box. That's where the tip-over valve is held vertically.

 

[Falaholic]

Ok, I think we got alot of the confusion out of the way.
My plan to do an AUX tank was to block off the vent, and drill right into my filler cap. Barb fitting, and open line straight to the AUX tank.
Fill up main tank as usual, place cap back on, proceed to fill up AUX tank. By the time the AUX tank is full the residual space in the filler neck and AUX fuel line to the main tank will have filled.
Am I correct in planning my AUX tank this way?

 

[davesax36]

Maybe. You'd have to see if the stock cap will remain sealed with the pressure of the fuel from a gravity-fed aux tank pushing on the fuel.

Somebody will know about that, but I'm not going to destroy a stock gas cap to find out.

You would need a vented aux tank if you block off the stock vent.

 

[Miles Long]

Please more info on this.
My original thought was to drill into the main cap and run a line from the AUX tank to the main cap.

Gentlemen -
I've posted some pics of the smaller aux. tank setup in my "personal file", or whatever it's called. Just click on my name to access.
As for the vent arrangement for this setup, you can see a small rubber hose going along the length of the tank. This is connected to the original vent/tipover valve tubing, by way of a hollow connector. The main tank vent has been plugged off, because it is lower than the potential height of gasoline with the aux. tank in place.
The other end (not shown)goes into a bung that was welded on the top of the tank. The cap and filler pipe, made from 1 1/4" brass sink fittings, is not vented.
As for the larger tank (pics below), it is vented in a similar fashion. The filler pipe is incorporated in the side of the trunk. I fashioned an end for it out of a PVC fitting that duplicates the shape and dimensions of the OEM filler neck, so that I can use the original locking cap. The small pipe coming out the side is the outlet for the fill indicator (I used a clear gas filter for this, with the paper element removed). The indicator is visible just below the red marker light. A ball floats to the top when the aux.tank is filled completely.
Both tanks use a 45 degree 1 1/2" PVC elbow to line up with the main tank filler neck, and are joined by using rubber plumbing couplings and hose clamps.
Cheers!

 

[BLKMAX]

I made a spur of the moment run to San Diego a couple of months ago. Wanted to get there as fast as I could. Spent way too much time stopping for gas (7 times 820 mi.) then I wanted. This is what I need for sure. Thanks for the IDEA!

 

[Falaholic]

As for the vent arrangement for this setup, you can see a small rubber hose going along the length of the tank. This is connected to the original vent/tipover valve tubing, by way of a hollow connector. The main tank vent has been plugged off, because it is lower than the potential height of gasoline with the aux. tank in place.

This is where I got lost.
My understanding is that the entire system is venting off of the AUX tank. What I don't understand is why the main tank's vent tube was extended further up the track, but then plugged. Why not just plug it without extending it?

 

[davesax36]

I think you're right...

It is venting off the aux tank, BUT the vent line (from the aux tank) is extended to connect to the original tipover valve. It does not connect to the original vent pipe, just to the valve.

 

[Miles Long]

This is where I got lost.
My understanding is that the entire system is venting off of the AUX tank. What I don't understand is why the main tank's vent tube was extended further up the track, but then plugged. Why not just plug it without extending it?

I'm guilty for passing on misinformation. It's been years since I added the aux tanks, I had forgotten the specifics. So here is some new pics (and removing the tank cover and driver's seat gives me an opportunity to changeout the garage door opener battery, which I have been puttin' off)
Yes, the original vent is still in use(minus the brass orifice), but as you can see it does not go down to the battery box location. It goes up and eventually connects to the seat pan, by way of the brass connector just visible. Incorporated within the seatpan, not visible, is the original tip-over valve.
So air is able to enter/exit the main tank, but the height of the vent line prevents leakage when the aux. tank is full.
And no, this smaller tank does not have a separate vent bung on top, as the larger tank does. The cap itself is vented, by means of a loosely-fitted gasket.
The bottom line is that neither tank arrangement has had any venting issues .
One problem that did occur happened before I began using the underseat tank......
my first mod was a straight filler pipe, from the main tank elbow to the "V max" logo plate (this used to be hinged). This allowed me to fillup without popping the seat, BUT the pipe was too low, just barely above the level of the main tank. Filling was a slow process, because the gas would back up and spill out.
Needless to say, that mod had a very short lifespan.
Cheers!

 

[Falaholic]

Perfect, got it. It all now makes sense.

 

[frank5079]

Just a thought here...how about using the auxiliary tank as the main tank, then as it is nears empty, and the engine starts to starve for gas, switch to the bike's main tank and go on.

 

[Miles Long]

Just a thought here...how about using the auxiliary tank as the main tank, then as it is nears empty, and the engine starts to starve for gas, switch to the bike's main tank and go on.

Could be done this way, but WHY?? You would have two switches/ valves to work - the aux/main, and the OEM reserve.
There's a lot to be said for the K.I.S.S. rule. That's why it has survived throughout the ages.
The Aux. should dump into the main, regardless of the setup. Essentially one tank, one fillup, one reserve switch. And a longer range between fillups.
Cheers!

 

[D-Max2012]

One guy posted that he has the main tank filler hose leading to the bottom of the aux tank. I guess K.I S.S would apply here.. (Step 1) Run a BIG tube from the Main tank filler hole, to the bottom of the aux tank. This way, filling both tanks at the gas station would be simple and quick. (Step 2), run a long 5/8 tube from the breather fitting, up and out next to the filler of the Aux tank. (make it long enough to go slightly higher than the neck filler cap). That way, both tanks will have 1 atmosphere of pressure while riding.

My analytic brain has me wondering about 1 thing.. When bike is at rest. How good of a seal on the pumps diaphragms? Can it halt the positive pressure of a filled aux tank that is sitting higher than the pump itself?.

I mean,,,, Can it fully stop gas from leaking past the pump, into the carbs, cylinders, or up the vent pipes of the carbs, if there is a little gap on any of your float needles?

Could it cause the bike to run rich, till the Aux tank is depleted?

Since the bike was designed to draw fuel up hill, via a pump, how would the system react to being fed from a down hill position?

Inquiring minds wants to know :biglaugh:

 

[Miles Long]

One guy posted that he has the main tank filler hose leading to the bottom of the aux tank. I guess K.I S.S would apply here.. (Step 1) Run a BIG tube from the Main tank filler hole, to the bottom of the aux tank. This way, filling both tanks at the gas station would be simple and quick. (Step 2), run a long 5/8 tube from the breather fitting, up and out next to the filler of the Aux tank. (make it long enough to go slightly higher than the neck filler cap). That way, both tanks will have 1 atmosphere of pressure while riding.

My analytic brain has me wondering about 1 thing.. When bike is at rest. How good of a seal on the pumps diaphragms? Can it halt the positive pressure of a filled aux tank that is sitting higher than the pump itself?.

I mean,,,, Can it fully stop gas from leaking past the pump, into the carbs, cylinders, or up the vent pipes of the carbs, if there is a little gap on any of your float needles?

Could it cause the bike to run rich, till the Aux tank is depleted?

Since the bike was designed to draw fuel up hill, via a pump, how would the system react to being fed from a down hill position?

Inquiring minds wants to know :biglaugh:

Cool questions, I've never considered the height thing at all.
Yes, my aux tank position would be maybe 6 inches? higher than the fuel pump, but apparently the weight of the extra gallon or so of fuel does not exert undo pressure on the pump diaphragms - because if they were leaking by and filling the pump and carbs, I wouldn't be getting the pump filling noise when switching on the ignition, after the bike has sat idle for awhile.
As for the venting arrangement, I use the original vent tube, minus the orifice, with the 5/16" hose terminating just a tad higher than the aux. filler cap. Just as you describe. Everything works just dandy.
Cheers!

 

[thor_eyerdhal]

No one provide an aftermarket tank to replace the stock one in US?

Here we can find a 20 liters one.

 

[D-Max2012]

Well, If you're getting the pumps' primer noise at key-on, then the bowls are not self filling.
That's good to know.

I may have to look into getting an aux tank setup..
Tanks,,, I mean Thanks :eusa_dance:

No one provide an aftermarket tank to replace the stock one in US?

I think someone on this forum, custom makes a larger tank, but it requires a bit of modding the battery compartment and some other modifications.

 

[davesax36]

Sean makes a tank that adds a gallon, but it only works with a 3"+ extended swingarm.

Sent from my SM-N900V using Tapatalk

 

[Miles Long]

Well, If you're getting the pumps' primer noise at key-on, then the bowls are not self filling.
That's good to know.

I may have to look into getting an aux tank setup..
Tanks,,, I mean Thanks

Looks like we've gone full circle on this one, D-Max!
Check out Dave 36's first post on this thread.
These "Tour-Tank" products seem to be unbeatable, when it comes to options and prices. Others on this forum have used them as well.
One of the options is extra bungs. I'm sure if you wanted a tank that dumped into the main, they could accommodate you. Of course you would have to supply some pics, calculate the bung diameter and angle, etc.
Your rear seat would have to be re-worked for the filler pipe, OR maybe the tank could be positioned to replace the rear seat, with a cover over it. I believe another member modified a rack tailbag just for this purpose, hiding the aux. tank completely.
You are only limited by your imagination, and how much time and effort you want to put into it. I guess this would apply to any modification.
Cheers!