Motor's Auxiliary Fuel Tank

This is one very well done project that Motor designed for his Concours14. I asked him to share this with y'all. He very graciously obliged. So without further ado. Motor's Greatest Farkle (His auxiliary fuel tank)

Thanks for doing this Motor!


Edit to add actual fuel capacity:

I was looking to add an aditional 4 gal initially, but with internal baffles and proper dimentions gave me 3.6. I can now travel 315-345 miles on a combined tank of gas. I ride it as fast as I can get away with so a more reasonable 70-75 should yield much better results. I just can't bring myself to ride slower!! :). I currently have it set up with a fuel pump and wired to my dash. I just flip a switch on the road and fill up the main tank. Last year I road from Mpls,MN to Memphis,TN and only stopped for gas twice. Got off the bike for a total of 1 hour during that trip.



Well during the winter of '09 I got this brain storm of an idea that I wanted to build an aux fuel cell to lengthen my time in the saddle while on road trips with my buddies. I searched all over the web but was unable to find anything that I liked or thought looked good enough. About the closest thing was AussieDave's set up (RIP :(). It wasn't bad but it lacked the custom look I was looking for. I started out by using that 'great stuff' foam. I bulit it up and then started to cut it to shape. Well it didn't work so well becuase it was pourous and a bit fragil.

 So I decide to try a different tact. First I cut out a template of the shape I wanted. I wanted it to fit between the stock grab handles on the bike. I knew I would not have a passenger along on my distance trips so I decided that I would place it in the pillion seat area. I next started by stacking up 3 pieces of 2" thick foam insulation and then  shaped it to my liking.

After I got the shape right I took it to my local fab shop and talked them into building me a one-off. The shop is called "Oakdale Precision machine" located in Oakdale, MN. They did an exceptional job turning my design into reality. All in all the tank consists of only three '3' pieces, the top, bottom, and front plate. I was amazed that they could get their machine to cut, bend, and shape like it did. I originally asked them for an aluminum tank but they advised me that it would be harder to create. So I excepted their opinion and went with stainless steel.

Before they closed up the tank, they added internal baffels. They next added the bottom supports, and the fuel filler neck. I purchased a flush mounted gas cap (aluminum) from ebay with a steel colar. The fab shop followed my design and cut it so when the bike was up-right on the center stand it would be level with the ground.

After they got it all stitched up they welded on my mounting tabs where I needed them, closed up the sides fo the supports, and welded on my bungs for my vent hose and filler hose. The next thing I did was to purchase a fuel pump, fuel filter, approx 10 ft of braided hose line with an ID of 3/16", and all my necessary fittings. Before I could put them all together, I needed to get a quick coat of paint on it. I just used some grill paint so I could use it a bit before I sent it off to the painter.

Now that my tank was completed, I next had to tap into the main tank so I could transfer all that extra fuel!! This was the part that caused me the most anxiety. You only get one shot to get it right or else it's a new tank. First things first, getting the tank out. loosen and remove all the bolts and disconnect the hoses and connectors. I slid a piece of wood underneaith the tank to help since it was just me in my garage.

Now that the tank was removed, my next step was to remove the fuel pump, open the gas cap, and then set the tank outside in the sun to evaporate any remaining fuel that I was not able to siphon out. After the tank was dry, it was time to drill!!  I had determined before removal that the lower right corner would seem to work best. It appeared to have the most room when mounted to the bike.  I used a stepped drill bit. This was useful as it only made small holes until I got to the required size. I did read that you didn't want to use a bit that was the correct size as it can cause the tank to 'tear' :-\.  As I was drilling out the hole, I placed some cotton into the inside of the tank to catch the bits of metal. I also flused the tank to clean out the remaining bits not caught the first time.

Now that the tank was tapped it was time to put in my fittings. I originally attached the hose directly to my tank fitting but thru trial and error found out that the hose was getting pinched and my fuel transfer was sloooooow. So I took the whole thing back apart( yup, major pain in the butt!!) and attached a 90degree fitting. Problem solved!

I wanted to be able to take the tank on and off so i installed a fuel line quick disconnect. I placed this far enough towards the aux tank so I could leave my main seat on. There were two types of quick disconnects available, metal and plastic. The metal was quite a bit more expensive. I chose this because I didn't want the plastic one to break on me thru some weird cosmic event. Oh ya, I almost forgot, don't forget the backflow valve! Also here are a few pics of how I attached the tank to the bike. I have a rack from premier cycle accessories, the tank attaches by three screws to the rack and is held up front by the two prongs that fit underneith my Corbin saddle.

To protect the fuses and other stuff directly underneith the pilion saddle, I got some rubber floor mat and cut it to size so if any rain got underneith it would not affect anyting. Works like a charm!! I got it all hooked up and connected to power, I placed the fuel transfer switch on the dash. When my low fuel light come on I reach up, flip this switch and in less that 10 min my tank is full again..

Now that everyting was assembled, attached, and working properly. I sent the tank off to my painter. I used a guy in Rochester,MN  "Greg Austin". He paints bikes and has his own shop. I was extremely satisfied with his color match and execution. The last thing I needed to do was get a back pad made so I could lean up against the tank on those long rides. My machine shop made me an extra back plate the exact same size and curvature as the tank. I took this piece to a  guy I know who does upholstery for hot rods. He created a back rest out of leather that comlements my Cobrin saddle.

Please login or register.

Login with username, password and session length