RS Aux. Gas Tank question:

[Konrad]

I love my Roadsmith 5 gal. auxiliary gas tank! Having said that, I have a question for others with a similar setup: Is it safe to fill the tank with the full five gallons in hot weather or is it likely to expand to the point of overflow through the filler cap?
I've been wary of that and only fill to 4.5 gallons. I'll be interested in your responses, technical and otherwise.

 

[bikerbillone]

Ive filled my RS aux tank to the full five with no escape I can see, ran it right up in the neck. Not sure that's a good idea, but it just happened. I ran the main tank down some, then transferred some of the aux tank fuel to get it down in the aux tank to a safe level. I think you're safe with five gallons 'cause you'll have air space in the neck, just got to proceed with caution when filling or it will blow back.

 

[lgjhn]

I recently triked mine with a RoadSmith conversion.
IF I were on a trip where I knew I was going to use/need that fuel that day, I'd fill her to the brim. IF I'm just going to park it in the garage or shop for a few dys, especially in warm weather, I'd probably move a half gallon or so to the main tank. The conversion company told me that a full tank can expand enough to drip slightly in a hot garage although I've not had it happen...nor do I want it to so I play it safe and move some out of the aux. tank.

 

[vo2max]

No problems with overflow in the Texas heat.

 

[kb9osl]

Hi Konrad, I fill mine to as much as I can put in. I've not had any overflow problems period. I have let it sit in the sunlight all day and never even smelled gas. I try to keep the reserve filled at all times , I run out my regular tank then fill it back with the 5 from the reserve, when I check my trip odometer and its above 350 or so miles I'll top the regular tank off and fill the reserve tank. This way I always have fresh gas in both tanks, its really nice now that my reserve pump works after they installed a new float . pepper . Still trying to get back down to Madison and go to the Lighthouse with ya!

 

[Konrad]

No problems with overflow in the Texas heat.

THAT has to be the definitive test!! I was headed west through Poth, TX (I like to believe they named the place after me) last year towards the Pacific ocean when it got so hot and muggy I abruptly turned north so I could continue to breathe. If the tank didn't overflow then, I can't imagine it ever happening. (Incidentally, the Water Tower in Poth was featured in the movie "The Great Waldo Pepper" with Robert Redford, 1966, I believe. It still stands.)

 

[Bikerbozo]

Since I am looking at auxiliary tanks right now. Quick question for all of you. Are your tanks getting mounted in such a way as to use gravity to sent it to regular tank? Or are some using electric pumps? Having a 4 gallon tank and getting 20 mpg on the VW are not too good.

 

[David George]

I have a Roadsmith with the axillary rear tank. What I do is put the gas nozzle into the tank as far as it goes, this leaves enough space for expansion. The main tank has a neck on it, for the same reason I believe.

 

[07BlueCSC]

Since I am looking at auxiliary tanks right now. Quick question for all of you. Are your tanks getting mounted in such a way as to use gravity to sent it to regular tank? Or are some using electric pumps? Having a 4 gallon tank and getting 20 mpg on the VW are not too good.

The RoadSmith uses a transfer pump. CSC auxiliary tank is filled through the main tank filler.

 

[Calgary]

I selected the CSC kit for that very reason - RS & Hannigan use a pump - potentially one more thing to go wrong. The CSC auxillary tank on a Gl1800 gives you a total of 10 US gallons; filling through the main tank. It does take a few more minutes to top up the tank as fuel flows throughout the system. The fuel gauge functions normally.

 

[2Trikez]

My homebuilt GL1200A with MotorTrike body has a 2 gal. tank at present. Tank had filler neck in middle of tank which I moved to the one side and re-welded. Then I cut a 5" hole in the top of the fender and than could fill aux. and then main next. I transfer fuel after main tank goes down 1 bar on digital gas guage. Takes about 2 and 1/2 minutes to empty via electric mini-fuel pump (fused of course) to filler neck of main tank.

Have not had any issues since install...in 2007.

2TZ

 

[SMSgt]

My 2012 RoadSmith has an aux tank. They advertise 5 gal but on my first fill it would only take 4.5 gal. Now I know the tank was empty because I put the tank in, the original tank leaked so I had to replace it.
I keep mine full all the time and have not had any problems since I installed the new one. I made a mod on the tank vent and am going to mod the GL fuel vent as well but that is another story.
I routinely transfer fuel while I'm driving just to keep the main tank at or near full.

 

[Konrad]

My 2012 RoadSmith has an aux tank. They advertise 5 gal but on my first fill it would only take 4.5 gal. Now I know the tank was empty because I put the tank in, the original tank leaked so I had to replace it.
I keep mine full all the time and have not had any problems since I installed the new one. I made a mod on the tank vent and am going to mod the GL fuel vent as well but that is another story.
I routinely transfer fuel while I'm driving just to keep the main tank at or near full.

Assume your main tank is half full and you begin the transfer from the reserve while riding and encounter some heavy traffic which requires all your attention and forget to turn the transfer off. I did that. The engine quit - choked out and I had a rather large puddle of gas under the bike on the side of the road. I got off and walked away while I waited for the excess to drain. About 20 minutes before the bike would start again and run normally. Not the safest situation! Lesson learned. I now go by the book and wait for the low-fuel light to come on and then transfer the entire reserve. When fillup time comes I know the reserve is empty and I fill it until the pump says 4.5 gal. Then I switch the nozzle to the main tank and top it off - and make certain the transfer pump is NOT running.

 

[bikerbillone]

Good post, Konrad. I have had the same misfortune, but was able to catch it at the first sputter, putt on until it had cleared.

One danger is waiting until you're down to the near 'E', is if you have some kind failure with the pump or electrical connection, you have a problem unless there fuel within the range of the fuel in the main tank. That happened to me, it was a simple connection in the off/on switch and I was able to make the next fuel station. I start my transfer pump at about two bars from E, or sometimes one bar but never less than one. That should work even if ya forget, since it will only transfer about 4.5 gallons.

 

[cirbtap]

I have a question about the aux. tank. Once you have your bike triked, can you have a CSC tank installed ???

 

[SMSgt]

Konrad, that is what I was talking about for a mod this winter. I'm going to vent the main tank into the aux tank which vent I have already modified, that way if you were to leave your transfer switch on and overflow the main tank it would overflow back to the aux tank and thereby be just a return line for fuel. It would never overflow the aux tank vent because there isn't enough fuel on board to overflow the aux tank vent.
And by the way I'm going to put the Honda charcoal canister on the aux tank vent. Simple fix.

 

[SMSgt]

bikerbillone, That is the exact reason I transfer on the fly. If something isn't working I want to know before I'm stranded. I plan on putting another fuel pump on mine for a backup. It will also make transferring twice as fast, if I want.

 

[07BlueCSC]

I have a question about the aux. tank. Once you have your bike triked, can you have a CSC tank installed ???

To install any aux.tank, you would have to remove the trike body.

The CSC tank might fit other trikes but then again it might not.

 

[Konrad]

Konrad, that is what I was talking about for a mod this winter. I'm going to vent the main tank into the aux tank which vent I have already modified, that way if you were to leave your transfer switch on and overflow the main tank it would overflow back to the aux tank and thereby be just a return line for fuel. It would never overflow the aux tank vent because there isn't enough fuel on board to overflow the aux tank vent.
And by the way I'm going to put the Honda charcoal canister on the aux tank vent. Simple fix.

Sounds like a plan! But you are way beyond me technologically.

 

[SMSgt]

I recently triked mine with a RoadSmith conversion.
IF I were on a trip where I knew I was going to use/need that fuel that day, I'd fill her to the brim. IF I'm just going to park it in the garage or shop for a few dys, especially in warm weather, I'd probably move a half gallon or so to the main tank. The conversion company told me that a full tank can expand enough to drip slightly in a hot garage although I've not had it happen...nor do I want it to so I play it safe and move some out of the aux. tank.

When I first got my RS with the aux tank it leaked a steady stream, when in the heat. They sent me new tank but would not honor their own statement from the owners manual and reimburse me for replacing the tank. Their tank vent system is a bad design and they know it, that is the reason for the leak in the first place.
I modified the tank vent to prevent the same problem in the future.
I put a T in the vent line that goes from the top of the tank to the fill hose so I could vent to outside air then I put a filter on the new vent line.