Aux Fuel Tank

[pmc847]

Here is the first look of the Aux tank with 1/4" hose and QDs.

Also, the vent situation. If you don't want to install a vent into the BMW tank then I think routing the vent hose up the left side, loop around the front rebound knob (higher than the fuel level in the main tank) and then down and T into the vent coming out of the tank access panel then I think that will work just fine. But I still like the vent into the main tank for a cleaner and somewhat safer setup.

I still need to weld on the computer bracket and the mounting brackets. Pics to follow soon.


Your thoughts please.

Philip

[steve abella]

Looks neat
what is the volume ? will it fit ABS models?

[pmc847]

More pics.

[pmc847]

This one is about 1.2 gallons. I'm also going to make a 1.4 gallon tank for those who have the short battery. These will not work with ABS.

Philip

[VetteRacer]

Philip. Thats an awesome looking item. Not knowing the bike too well, I am guessing that would be always full? Whats the plumbing system look like for it?
Matt

[motoyoyo]

Phillip, the tank looks really nice. You should also make sure there is adequate clearance between the main tank and the aux tank. If there is any metal to metal contact it could either be noisey or cause a premature leak. I like the separate vent line for those of us that want a bolt on solution. There are some nice tank vent check valves available too that could be used inline at the high spot in the vent line, for extra safety:

[Mikeypro]

Very slick. Let me know when you have it tested and ready for public consumption: I'm riding out to Las Vegas and back in April and sure could use the extra 1.4g!

[ejfbmw]

Would be interested to see how it is connected into the fuel system.

Good work.

E

[pmc847]

Matt,

I figure that by the time you stop for gas, like on a normal Sunday ride, the aux tank will probably still be half full. Currently my main tank holds just shy of 5 gallons, with the addition of the 1.2 gallons from the aux tank I fell my total range would be 240+ miles (@40mpg).

E,

The plumbing is very simple. Just disconnect the main tank balance hose (bottom of tank left and right side) and just connect the hoses provided with the aux tank (quick disconnects included). As you can see from the pics the aux tank sits in front of the battery and the computer will be attached to the front of the aux tank. The vent can be routed to atmosphere or to a new vent in the main tank (no welding required). If going to atmoshere a tank vent check valves would be highly recommended.

Scott,

Great idea about the tank vent check valves. Where did you find them? Please send a link.
The clearance looks adequate, about 1/4" at the closes points.

Philip

03 R1100S BCR #44
Staintune
InDuct
SJ PowerFilter
FIM Chip
Ohlins
Throttle bodies matched to rubber mounts matched to heads
Exhaust pipe welds ground down

[motoyoyo]

Phillip, here is a link for a new style tank vent valve they are using on dirt bikes: http://www.motoworldracing.com/motocrossplus_04_ventcap.html It might do the job and it certainly is compact. I haven't seen one to tell if they are adequate or not for this application, but nice looking and simple.


Also, here is a link to the other style vent valves I posted earlier: http://www.newton-equipment.com/ I just found them thru an internet search, but should provide some good info. You can also find fuel tank vents for autos that should do the job too: http://www.drivewire.com/OEMResult/CTDFuel_Delivery~CTC32~SCDFuel_Tank_Vent_Valve~SCC 2061.html

BTW, I was wondering what the two fittings were for at the bottom of your aux tank. After looking at your layout, you probably don't need both lines attatched to the aux tank for fuel delivery. One fitting with QD's tee'd into the balance line should be all that is needed. As long as the vent line is functioning, the tank should fill just fine with one line. Are you planning to weld on mounting points for the computer at the front of the aux tank and maybe hold down mounts for the tank itself? This is looking very interesting indeed. Nice work.

[Firebolter]

Very slick, nice use of "wasted" space. More details please after you have run it for awhile...

[roger albert]

Really nice work. Do you have even a wild assed guess on price yet?
It looks more and more like something I want.

One caveat, I'd like to ditto the concern about adequate clearance between main and aux tanks. Motion between supposedly fixed parts can be pretty great when looking at combinations of vibrations and jolts.

Good luck.
Roger

[ejfbmw]

Will the aux tank drain/empty into the main.

In the sketch, it looks like it is mounted lower than the main tank.

[Flatbutt1]

Almost makes me sorry I have the ABS. This is nice work that I'd like to take advantage of.

[pmc847]

Scott,

Thanks for the info on the vents, I'll check it out.

Yes you can get away with just one input/output for the aux tank, should work just fine but it would be very slow filling up. If someone only wants one source in and out I will be glad to provide a tank set up that way.

The tank is going back to my friend to have the computer mounts and the tank hold downs welded on. As soon as I get it back I'll attach pics.

Roger,

Clearance is currently about 1/4" at the closes points which is the top left and right edges. Tank will be secured at three points, front, left and right.

E,

The aux tank is at the same lever as the left side of the main tank and slightly higher than the right side of the main tank. Flow should be no problem.

Philip

[The Sea Dog]

You could always mount some rubber stripping along the edges of the aux if you're concerned about touching. It's looking good, any idea of an approximate cost yet ?

Cheers
PAul

[pmc847]

Paul,

At this point I have no real good idea what it is going to cost. I know the price of all the fitting but no idea of what the tank itself will cost. If my friend Larry, sheet metal worker, wants to do them in his spare time then the price will be a little less than if I have to find a fabricator to do the job. What do you think would be reasonable?

Philip

[pmc847]

Roger,

Did you get my PM last night? What do you think about it?

Philip

[roger albert]

yes, and sent one back, actually two, since the browser crashed on the first one.

if it's not working, try me at ralbert@austin.rr.com too.

Seems like a good idea.

roger

[pmc847]

Here is the completed prototype. I just did a pressure test and found 4 pin hole leaks. Will have to wait till next week to have then repaired.

I'm going to send this unit to Roger for shake down testing because if I do it myself it will be another 2 months before the weather is good enough to get my bike out.

I'm ready to start the prototype for the slightly bigger tank and have come up with a different/better way to do the fuel lines into the tank. Currently the battery/tank holder needs to be cut/notched to accept the right side fuel line. The new way will eliminate any modifications to the bike. Just remove the main tank fuel balance tube and attach the fuel lines from the aux tank. The aux tank vent will need to be routed up, over and around the front shock rebound knob. The vent hose needs to be routed higher than the main tank fuel level. I still plan on venting mine into the main tank as I've shown before. An inline vent one-way valve can, and probably should, be installed to help prevent overflow. Also, I will use nut inserts on the hold down bracket to eliminate fumbling with and droppings nuts, especially on the front mount. By the way, the tank is secured at three points, front, left and right.

As you can see by the pics the prototype looks a little crude. This will be addressed if there is enough interest to justify production.