Mount Aux Tank on FJR- Help

[Jeff C]

Hey all,
I want to mount a 4.5 gal Sandstorm tank over the passenger seat of my 2020 FJR as to not interfere (or integrate) with Givi Top case mount SR357 ...and can find no solutions out there. Seems like all vendor activity in this area has died off in the past year or so; Garauld retired, Maple Farkle shut down, etc...
Garauld's rack was the ideal solution but he's on the beach (God bless him).
I think I can handle the plumbing (thanks to so much good info on the forums) but....I shamelessly admit, I don't have the skill set to fabricate a rack from scratch in my garage.
Any solution needs to pass IBR reqs.
Does anyone know of a vendor who are actively providing mounting/rack solutions.

Appreciate the help

 

[Marc11]

With the images available I bet a local welder could build something for you pretty quickly.

 

[EricV]

Something like THIS or THIS might get you started, but would have to be secured with more than the seat latch. I've seen aux tanks go flying off the bike during a crash with only the seat latch securing them. It needs to be bolted down.

Honestly, you can fab your own. Find a water jet company near you, cut out a piece of cardboard the shape you want, take it to the water jet company and have a piece of aluminum plate cut to that shape. Now you just need some spacers and tabs and a welder to weld them to the plate. There are two bolts strait down and two that angle back at 90º that can be used for mounting the plate in place of the seat.

 

[kerrizor]

> I've seen aux tanks go flying off the bike during a crash...

I got told that having an aux tank was going to result in my having a broken back, so this seems like a feature?

(J/K, secure the tank properly, folks!)

 

[EricV]

Well, it did hit the rider in the back of the head...

 

[keithu]

I built a really solid rack using T-slot aluminum tubing from 8020.net. Here's my write-up:

https://forum.ironbutt.org/index.php?threads/fuel-cell-rack-using-80-20-tubing.3837/

This stuff is like an erector set for grown-ups. If you can use a hacksaw and a 4mm Allen wrench, you can build a strong rack.

 

[danklyrides]

I want to mount a 4.5 gal Sandstorm tank over the passenger seat of my 2020 FJR as to not interfere (or integrate) with Givi Top case mount SR357

Jeff,
I had the exact idea, but I replaced the pillion seat with my tank. 4.5 gallon SandStorm with 3/8" NPT out and 1/4" shootout vent that needed to be mounted so as not to interfere with my Givi SR357.

I couldn't find a great place to mount a bulkhead fitting on the bottom of my tank so I had a fabricator weld a stainless steel -6 AN bung on for me. The only part of the tank that has much clearance underneath is forward so I had them weld it left of center near the front. This allows me to route the hose across to the right side and down the right side. I have a -6 AN cap that I can put on the bung when I remove the aux tank.


1/2" aluminum plate that I designed on CAD and had www.sendcutsend.com cut it for me. 1" X 2" X 6" aluminum riser blocks on either side. -6 AN aluminum fittings for fuel hose routing. NAPA universal 5/16" in/out fuel filter (not the one shown). Powder coated steel tank brackets that came with the tank.


The notch in the plate is to clear the seat latch bolts and the area around them that isn't flat. The risers and brackets are secured with nylock nuts.



I mounted the plate on 6 points as shown here. I built spacers for the front 4 mount points out of washers that I stuck together with RTV. The spacers allowed for the plate to be level from front to back so there wasn't any gapping. The front bolts are M10 and inserted from above through holes I drilled with nylock nuts underneath. The middle bolts are M8 X 1.5 that go through the SR357 and thread into the factory rack mounting points. I drilled holes for the rear M8 bolts that were inserted from below with nylock nuts on top








I dilled a hole below the tail light, ran the hose under the license plate, and zip tied it to the rear fender. The vent works well and stays clear of the rear tire.


For some reason, I don't currently have a wide shot of the finished product. This is the mockup I did in the early phases and it looks very similar to what I ended up with.


I have a total of 11.1 gallons now, which gives me a range well beyond the 350 limit for normal IBA rides. The tank drains completely via gravity. I just wait till I had about a 1/4 tank, open the valve, and leave it open until I fuel up.I rode from Boise, ID to Salt Lake City and back last week. It is 355 miles each way and I made it with 1.6 gallons to spare. As an added bonus, I can bundle up a hoodie and bungee-net it to the front of the tank for a nice backrest.

 

[EricV]

@danklyrides - I have a small problem with your math. You say you have 11.1 gallons and used 9.5 gallons to travel 710 miles? That would be nearly 75 mpg and the FJR is more like 42-45 mpg loaded up at highway speeds. The aux tank either holds more fuel than you believe or something is up with the numbers. Even w/o bags and with a tail wind, I don't see you getting that mpg.

Excellent write up and fabrication. I'm a fan of overkill.

 

[Shawn K]

I'm guessing he meant 9.5 gallons each direction, but I thought the same thing that you did.

 

[EricV]

I'm guessing he meant 9.5 gallons each direction, but I thought the same thing that you did.

9.5 gallons each way would be horrible mpg on a FJR. I'd be looking for a new engine if I was getting 37 mpg! I averaged 42 mpg in rally mode over a 5000 mile rally when I was running at FJR nominal much of the time.

 

[danklyrides]

Yes, it was 9.5 gallons each way. Sorry for the confusion. I measured 38 mpg for the trip down with the cruise set most of the time at 88.

 

[EricV]

You must have a barn door for a windscreen.

 

[Auburn]

Yes, it was 9.5 gallons each way. Sorry for the confusion. I measured 38 mpg for the trip down with the cruise set most of the time at 88.

You might explore getting the ECU flashed by Ivan's Performance. The ones that I know about are averaging much higher mpg and getting much better performance from the bikes. Mine got over 42 towing, two up after the flash. I know of some that are in the 50+ range.

 

[c10]

I was always averaging mid 40's , and occasionally low 50's if I was keeping out of throttle in Ozarks . I ran PC V with auto tune , but had removed 50 ish pounds from my FJR . I had extremely modified the air box for dual inlet on each side with a K&N filter. It was nice the distance it covered quickly . Your rig looks well put together .

 

[Jeff C]

Jeff,
I had the exact idea, but I replaced the pillion seat with my tank. 4.5 gallon SandStorm with 3/8" NPT out and 1/4" shootout vent that needed to be mounted so as not to interfere with my Givi SR357.

Thanks Alex- That’s a nice looking build.
Very clean.
I appreciate the effort to get it on the forum to help others. You’ve given me some good ideas.
Enjoy it.

 

[Jeff C]

Alright - I'll complete this thread by posting my finished project for those who are looking to undertake a similar project in the future - Here's one solution.
Gravity fed and tank drill.
I got help from a buddy who is a professional welder (everyone should have a welder friend in their friend-portfolio) to create a simple but solid rack to hold a cylinder gas tank onto my FJR...and drill & weld a fitting into my stock tank.

Here are the pics and hardware list.
I used 4-AN / 1/4 in fuel line - at first I thought it was gonna be too small until I fed it through the bike and thought to myself "I'm glad its not any bigger". Transfer rate of ~10 minutes per gallon should be more than adequate.
I plumbed it with two disconnection points; close to stock tank and right at the aux tank, a valve shut-off valve and an in-line filter.
I can have it taken off the FJR within 25 minutes or so.
I have tested the plumbing line for leaks (success) and fuel transfer on the complete system (success- about 50 minutes for 4.5 gallons). Gonna take it out for a short 1,800 mile ride next week.
Thanks everyone who posted on this topic over the years here and the FJR forums as well as those who provided input directly.

 

[Jeff C]

Here are the pics and hardware list.

Allstar Performance Weld-On Bung AN-4 – Welded to Stock Tank

SYKRSS 4AN 90 Degree Bulkhead Fitting Adapter AN-4 – Connected to Weld-On Bund

EVIL ENERGY 4AN Fuel Line Hose Fitting Kit Braided Nylon CPE – Fuel Line 4AN / ¼ in.

Jiffy-tite 2000 Series Quick-Connect Hose Ends 21604

Jiffy-tite 2000 Series Quick-Connect Hose Ends 22604

K&N 81-0221 Fuel Filter In-Line Gas Fltr 1/4 Singlepac

Oregon 07-403 Inline Fuel Shut Off 1/4" Ball Valve

10x14 Center Fill - 4.5 Gallon w/ Baffle shootout vent 1/4 NPT

1/4" Line Quick Disconnect - Outlet Fuel Line – Connect to Aux Tank

 

[EricV]

Thanks for sharing what you've done. You're in TX.... Nothing is ever too big. Check out the instant MPG when you're going 85+ next time.

And please explain why you felt anything could be too big on a gravity feed system on the FJR.

On your next one, and for anyone else reading this thread in the future, please present your plan before you get started or order any parts. A helpful discussion and suggestions, with real world experience will result and you may find reasons to change your plan.

 

[Shawn K]

I was kind of surprised at the use of 1/4" tubing on a gravity feed FJR. I would've thought that 3/8" was a better choice, but that's just pure speculation on my part.

 

[EricV]

In rare situations I have over ridden the gravity feed of 5/16". The only real issue with larger tubing is fitting it from the aux tank to the main w/o a kink or loop/hoop over something that might cause an air bubble to form in the line at the top of the loop or hoop. There isn't all that much room under the seat of a FJR. I cut the plastic tray away in a couple of spots to get as strait a path as possible from the aux tank valve to the main tank bulkhead fitting.

I hope what Jeff has done works great for him. My opinion is -4 and 1/4" ID hose is too small for good feed. The whole point of a gravity feed system is to balance itself out so the main and aux tank drain together equally. You really don't want the main dropping faster than the aux, which leaves you not really knowing how much fuel you have on hand. The aux can't drop faster than the main in a gravity feed, (unless you've inadvertently pressurized the main and it's blowing the aux fuel out the aux tank's vent line behind you).