Extra Fuel Storage

[HarpHD]

I have built my own fuel cell to fit in the bottom of the rear hard case. It only uses up about 3 inches of space, has built in baffles, has a flat top so the rest of the case is usable, it is vented back under the bike to prevent fumes and last but not least I've reiforced the mounting rack. My question is what is the best way to tie into the existing tank. I have read a post in bad weather bikers where a guy tied into the drain plug on the fuel pump, I plan to use a low pressure pump to transfer fuel. Anybody have a better idea or plan?

[Buellysses]

Hmm...
The drain plug seems like a reasonable place to go.

You seem like you have thought this through pretty well, but I just want to make sure I point something out... If the vent on the external tank is lower then the fuel level in your primary tank you are going to have problems.

How I would personally go about it would be to drill and tap a couple of barbed fittings onto the existing tank. One near the top and one near the bottom. Run hoses to the new tank, top and bottom. Make sure the lower fuel level of the new tank is above the lower level of the existing, and the upper level of the new is below the upper level of the existing.

I hope this would go with without saying... but drilling and tapping on an fuel tank isn't the brightest idea, but it could be done safely.

[xtremelow]

I would say use the drain plug but as stated you need to watch your fuel levels, one way around this would be to run a long breather type line. You could even run the second breather line into the stock one with a T-fitting and put a check valve that way each tank would primaraly over flow into each other but in extreme cases the check valve will allow for dumpage.

Again make sure the check valve is the highest point otherwise it will be the failure point.

[dave_xb12r]

If you were to run one line from the bottom of your reserve to the top of your tank, air pressure would pull gas into the main tank. Just make sure you vent the top of your reserve. When the reserve empties, it become the main tank vent. You shouldn't have to drill anything that way, but you may have to modify your vent on your tank.

[xtremelow]

Would it pull the gas into the other tank or just to the same heighth as the main tank within the line?

I know the fuel will pull up the line and into the other tank but the gas would have to be at some point higher than the vent to begin the suction process which could only happen if the bike was leaning forward drastically.

Am I wrong?

[dave_xb12r]

Xtreme, you're talking about a siphon, where one hose goes into both bodys of liquid, and both have to stay at an equal elevation(the poor mans level)

I'm talking about when the gas leaving the main tank causes low air pressure above it in that empty area. Because the reserve tank would be tied to that empty area, gas would be pulled into it.

[xtremelow]

Got ya, in that case would the gas cap provide a good enough seal to hold the proper pressure to pull the fuel?

[dave_xb12r]

I don't see why not.

But one thing I didn't consider is fill up

[HarpHD]

My fuel vent extends about 4 inches above the tank and has a 180 degree bend at the top that sends the vent hose back under the bike where I did T into the existing vent hose. I have considered useing a siphon setup to transfer the fuel but the problem is that the bottom of my external fuel cell is higher than the factory tank, which I think would cause it to over fill and dump through the vent in the factory tank. If I'm wrong please tell me otherwise the onle way I know to do it is either use gravity or a low pressure pump to transfer the fuel through the drain plug after I have ran the bike low on gas. This way it wouldn't over flow do to the fact the external tank only holds about 2.5 gallons. I hope to find a way to continuosly feed the factory tank without having to pull over so if I'm wrong please set me straight.