Another Fuel Cell Thread

[madmike2]

The Gravity vs. Fuel Pump debate:

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EDIT: Warchild posted while I was typing. See how "high" his tank is because the mounts hold the tank above the location of the missing pillion seat? Therefore gravity works for the benefit in this mounting design.

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If you'll notice, those that are gravity feed to the main tank are mounted higher. Usually the bottom of the auxiliary tank well above the center line or top of the main fuel tank. That way, once the main tank is 1/2 empty the rider can open auxiliary tank valve and let the gasoline transfer (after 1/2 tank so that the aux. tank doesn't overflow the main tank.

From what I recal, talking with those who have the Tanji cell, it will transfer to the main tank without a fuel pump, but they open it (as was mentioned by vectervp1) early in the main tank usage (like 100 miles) because it is so low, comparatively, it doesn't transfer quickly.

I assume that's why those who have made (or bought) auxiliary fuel tanks that are mounded low in the pillion position use fuel pumps to transfer from the auxiliary. If your tail bag tank is mounted below the pillion seat top then the aux. tank will be below the level of the gas tank unless the main tank is almost empty, thereby resisting the easy flow from the auxiliary tank.

 

[taterides]

If a tank could lock in like a gen 2 seat, would that be secure enough for a rally? Or is it required to be bolted? Been thinking about this a good bit. and want to do something soon. Spoke to a custom tank builder in Fort Lauderdale and that seems to be the direction I may go with him. Any thoughts good or bad? Idea is base locks in with a fuel pump under. Front of tank will have a radius to act as a back support. So everyone fire away!!!

 

[RoadGlide]

What am I missing here? I am still waiting for my FJR (5/30) but I guess I never realized how many SERIOUS lD riders there were on them. . .
I consider myself an LD rider tho I never entered any rallys - my longest day is just under 1200 miles. On my Wing 6-700 miles/day were typical when beating feet out west. I never though I needed an aux tank. Do you really plan on 400 mile legs during the day?

Uh, yes! Don't most FJR riders.

 

[RoadGlide]

Ok, I'll bite. I've been thinking about adding a fuel cell also. I saw one at the Cape Fear Rally that "Chuck" had on his LT1200. It was custom built. It was plumbed to the vent tube from the main tank. When the main tank used fuel it created a vacumm void in the main that sucked fuel from the cell that was vented. No other plumbing needed and it seemed so simple. So, just what the hell am I missing with this set up?

 

[Ignacio]

What am I missing here? I am still waiting for my FJR (5/30) but I guess I never realized how many SERIOUS lD riders there were on them. . .
Do you really plan on 400 mile legs during the day?

Cells are probably less about outright fuel "range" and more about adding fueling "options". During a rally it's gives one more choices about when to stop and less to worry about finding gas in a remote area. It's more like having a 250 mile reserve tank.

And the FJR as a serious LD bike? Well, in the '07 IBR there were 15 or more of them...and it was the ONLY model represented by Yamaha. 4 of the top 10 finishers were on FJRs.

So, just what the hell am I missing with this set up?

I'm guessing it wasn't quite that straight-forward. Are you sure he didn't tie it in with a fuel pump line, was carbureted or maybe it was just a gravity feed tee'd between a petcock and something?

The FJR and a fuel cell are a bit tricky because you either have to drill a hole in the tank and add a fitting for a gravity feed or auxiliary fuel pump assit...or if you were to comtemplate tying into the existing fuel lines you'd have to compete with a high-pressure pump that runs the injection system.

 

[RoadGlide]

****! I was looking for something simple and easy.

 

[ctfjr]

What am I missing here? I am still waiting for my FJR (5/30) but I guess I never realized how many SERIOUS lD riders there were on them. . .
Do you really plan on 400 mile legs during the day?

Cells are probably less about outright fuel "range" and more about adding fueling "options". During a rally it's gives one more choices about when to stop and less to worry about finding gas in a remote area. It's more like having a 250 mile reserve tank.

And the FJR as a serious LD bike? Well, in the '07 IBR there were 15 or more of them...and it was the ONLY model represented by Yamaha. 4 of the top 10 finishers were on FJRs.

lol - well although I don't follow the IBA or their rallies I had no illusions about the capabilities of the bike. I sure wouldn't have one on order if I didn't think I could comfortably do 700 mile days or ride straight through to Atlanta from home (1000 miles) if I felt so urged.

I guess in my mind I just separate rallying from LD riding. In looking at the custom tank that Warchild posted you have to admire the ingenuity & quality of the install. With all that available space under it why not extend it down into that space & either pick up more capacity or lower the overall height (same capacity)? It would certainly lower the center of gravity.

 

[SkooterG]

With all that available space under it why not extend it down into that space & either pick up more capacity or lower the overall height (same capacity)? It would certainly lower the center of gravity.

No doubt, WC's fuel cell give's him the IBA standard MAX combined capacity of 11.5 gallons or very near to it. And lowering the cell could very well interfere with sidebag removal. You need to take that into consideration.

IMHO, the changes to COG of moving the fuel cell up or down a few inches is totally insignificant. It really doesn't matter that much as it's centered over the centerline of the bike. Having a far greater impact would be moving it backwards.

And as far as I am concerned, you can't have TOO much storage space in a location like that. The fuel cell I use is a different design and has less room that the one Warchild shows. I wish it had a little bit more, even at the expense of raising the weight an inch or so.

 

[Ignacio]

With all that available space under it why not extend it down into that space & either pick up more capacity or lower the overall height (same capacity)? It would certainly lower the center of gravity.

The height is on purpose. If he lowered it....his fool-proof fuel pump (aka gravity) wouldn't work so well. The lack of pressure gradient would inhibit the last bit of fuel from the cell to the tank. You can be sure the height chosen is optimized to probably within a half inch or so.

In this case...gravity doesn't suck....it pushes.

He could try and use the Force or an electric fuel pump, but I think he's a tad skeptical of their reliability.

 

[ctfjr]

Makes sense Skooter & Ignacio - thanks

 

[odot]

In that case.......I'd put it up about three feet above the main tank. That's just me, though.

 

[Warchild]

No doubt, WC's fuel cell give's him the IBA standard MAX combined capacity of 11.5 gallons or very near to it.

Exactly correct. I originally designed this aux cell for the FJR, so using Yamaha's stated 6.6 gallons, plus 4.85 gallons I was right at 11.45 gallons. B)

Now, I recently installed that FJR cell on the new K8 Busa, and as you can see, the bottom of the cell sits well above the bottom of the stock tank:

This bad-*** set-up transfers 4.5 gallons of fuel in 11 minutes, which is damn lickety-split for a gravity system using a 5/16" I.D. fuel line.

 

[Feejer/Weejer man]

I have one of the first three Tanji cells he designed for his initial FJR IBR. They were gravity fed. It has been flawless except when I added a Wilber shock and the ride height lowered so it wouldn't drain the whole aux. cell. But I realized what had happened and fixed it. Even though I have never entered a rally I wouldn't be without it. As I travel the option for stopping when and where becomes greater and less bothersome. But I ride solo so its good for me.