2003 Tank Retrofit

[mik]

Al, I have to agree with you, the 03 tank does look appreciably better. What I'm really waiting for is your results on the fuel available for engine consumption. I have to thank you for your tenacity in persuing this project ...it seems that MG has forgotten to answer my inquiry, although they did attempt to reach me by phone.

I envy your youth and the stamina it affords...sigh, it all seems so long ago.

[al_roethlisberger]

OK, here are the results comparing tank capacity.

 

 

2002 - 5.69 US Gallon Total Capacity

 

110 ounces of which is normally "trapped" on the right side of the tank, which is not an effective reserve(see Wasted Fuel Thread)

 

 

2003 - 5.75 US Gallon Total Capacity, 135 ounces of which is "sorta reserve" (details below)

 

 

The 2003 tank has a similar total capacity, within a few ounces, of the 2002 tank.

 

Once filled, the 2003 tank will "run dry" at 4.70 Gallons(601 ounces), leaving approximately 135 ounces "trapped" on the left side of the tank, similarly to the "trapped" fuel on the right side of 2002 and earlier tanks with the external fuel pump.

 

The difference here is that since the 2003+ tanks have the internal pump/pressure-regulator loaded internally on the right side, and hence the fuel draw and return are on the same side(unlike earlier tanks), one can effectively "slosh" the fuel over to the pump side of the tank(right), and get to a significant portion. This represents the "reserve" of the 2003+ tanks. It isn't automatic, and is rather physically manual, but is doable by violently jerking the bike sideways to the right, or stopping the bike and leaning it to the right.

 

Now, here's the clarification on the 2003 reserve. Unless one is just lucky with a "hearty" slosh, or is able to reeeaaaaaaaaaally lean the bike way over to the right, my testing shows that only 59 ounces of the 135 ounces in reserve will slosh over to the right, and be available as an effective "reserve" once you run the tank dry.

 

That leaves 76 ounces still "stuck" over on the left side of the tank.

 

My testing showed that I had to turn the tank nearly a full 90 degrees to get this last 76 ounces to flow over to the right side of the tank, and I think this is unlikely to be replicated in the real world with the tank mounted on a motorcycle. So effectively, this fuel is just as "trapped" and "wasted" as the 110 ounces that are trapped on the right side of the earlier tanks.

 

Unlike discussions of tubes inside the tanks bridging the hump, etc. for the earlier tanks, the only solution for this half gallon is a balance tube. However, this would require some tank surgery, and for at best about 15-20 miles, I'm not sure it's worth it. After all, if you are that desperate, I bet you'll find a way to get that tank rotated nearly 90 degrees

 

Anyway, I'll think on it....

 

 

All in all, the new tank should get you a little better range more easily in practice(less continuous sloshing), but not much. It seems the primary advantage will remain a cleaner EFI fuel supply setup, and less susceptibility to vapor lock.

 

 

Bottom line, 2003 tank:

 

- Total Capacity 5.75 US Gallons

- Runs Dry(pumps air) at 4.70 US Gallons

- Reserve(fuel "trapped" on left side of tank) 135 ounces(1.05 US Gallons)

- "Sloshable" amount of reserve 59 ounces

- Leaves 76 ounces "trapped" on left side

 

 

Also, good to know... I measured 45 psi(3.1bar) on the new internal pump EFI loop which is the same spec as the older external pump, so that's good, although the flow of the internal pump seems a bit less vigorous than the unimpeded external pump

 

I've double-checked, and this is same pressure as delivered by the external pump on the 2002 EFI circuit. So no new fuel mapping should be required by switching from a 2002 to 2003 tank.

 

al

[mik]

Al, thank you for confirming what I had expected. There is at least a gallon of gasoline for reserve when the low fuel light appears. Enough, I expect, for another 30 or 35 miles before it has to be pushed. I think I'll get myself a siphon and carry it in the saddlebag.

[al_roethlisberger]

So, I took the tank down to my local plastics shop(TAP) and asked them about what might stick/bond to tank material itself if I wanted to build-out the bottom of the tank for additional capacity, and to "balance" both sides of the tank.

 

Well, after some investigation, the poly material that our tanks are made out of(and apparently quite commonly used for other similar applications, like those plastic cutting boards one can get) is specifically designed to be inert to most solvents(duh! ), and hence none of the myriad epoxies, solvents, etc. that the common man has access to... will work, and/or stay durable/flexible enough to be safe for a fuel-tank application.

 

They said that again, this is very common in regard to these tanks, and for example, in many cases if they get punctured, they often have to be replaced versus repaired.

 

The only option they recommended looking into was to have an experienced machine shop that works in plastics "heat weld" to the tank, but that sounds dicey to me.

 

I'll have to think on this some more....

 

al

[jrt]

My machinist had the same evaluation. The plastic tank won't take glue and in order to modify (add on to) the plastic tank, it needs to welded. BTW, he's an old (literally) fiberglass and plastics mold worker.

J

[al_roethlisberger]

Does he think it could be done "reliably" given the tank material? That's my concern.

 

I'm taking my tank down to a reputable plastics fabrication shop in a few minutes to have them give me their opinion. I've already had one shop give me their over the phone, and they didn't recommend it, and the shop I'm taking it to isn't too optimistic... as it depends on the tank material.

 

We'll see what these guys say, and I'll post the results.

 

al

 

P.S.

 

Have many of you ever wondered how heavy a full tank of gas is? Well, after all this "capacity testing" and lugging around full tanks of gas... I didn't weigh it, but lemme tell ya... I can't believe how heavy a full ~6 gallon tank of gas is

 

With this in mind, since most new bikes are fuel injected and or have fuel pumps not requiring a gravity feed, it's interesting that more new bikes don't have specially engineered/hidden tanks as low in the frame as possible to lower the CoG. This weight "up high" really makes a difference in handling when full.

 

Buell has the right idea

[al_roethlisberger]

OK, so I just got back from the plastic fabricators.... and it's a mixed bag.

 

They say they can weld material to the bottom of the tank to expand capacity, but one concern(also expressed by other shops) is that they cannot get inside the tank to weld both sides of the seam. Also, they have chopped/welded plastic tanks for moto-cross bikes with poor success. He said they usually split over time.

 

Of course, he also pointed out that those tanks were thinner, and actually cut-down, and very abused.... soooooo

 

We discussed reinforcing the welded panes various ways by using blocks/strips at the junction, so we'd have at least 2 welds sealing each seam, and he thought that would be quite strong and durable.

 

So, I'll go out tonight and measure just how much volume I can actually get out from under the tank with this modification.... see if it's worth doing(about $100), and think on it some more.

 

al

[dlaing]

What is the chance that a traditional tonti framed bike's tank would fit our frame?

 

This would be an awesome tank (28liters):

http://www.wbo-racing.de/produkte/moto-guz...tour/index.html

[gthyni]

Just be careful Al,

petrol and hot engines are not too play with:

 

more pix:

at Colin Edwards site

[jrt]

Damn- time to park that one!

[al_roethlisberger]

Damn- time to park that one!

 

Heh, you should see the next few minutes of the video and what happens next

 

 

But yep, you are correct in regards to the risk of messing with any tank, especially these new poly units, and hence my trepidation with this project.

 

But I think I've made my decision, and it's not to modify the bottom of the tank.

 

After doing some measuring and calculating using the old airbox lid as a guide, the best possible gain by "welding" on a bottom is about half a gallon(US). Just looking at the cavity under the tank, it looks like one could add a lot more, but by putting the old airbox up under there and measuring clearances, there really isn't a lot of room above the spine, that also provides a good "purchase" on the tank for this modification to weld to.

 

While half a gallon is significant, even with welding a box under the tank and tapping through the sides of the hump up under the tank, the saddlebag shape of tank would still put most of the "trapped" fuel below this modification... still "trapping" fuel.... although it admittedly would now be a bit easier to "slosh" over

 

 

Anyway, I don't think the benefit outweighs the risk at this time, and this is after talking to several plastic guys that basically said: "...uhhh, well yeah, I'm pretty sure we could weld it, but it'll probably separate again." I don't want that eating in the back of my mind over a long ride.

 

 

So if I pursue this further, I may just look for a small self contained tank that will fit where the filter and pump had been above the spine, and plumb it into the tank somehow. Who knows, but for now I think that unless one has a metal tank fabricated, or as JRT suggested have a whole new plastic tank made from scratch, this modification may offer too much risk for a minor gain... too bad

 

I may also still put a tap into the tank for a balance tube, but that's pretty easy.

 

 

But on a positive note, the 2003 tank as stock fits fine!

 

al

[al_roethlisberger]

Well, I picked up the repainted 2003 tank today and it looks great They did an excellent job preserving the 2003 decal, and matching the "Champagne" color.

 

 

Just need to rip-out all the "old" 2002 plumbing, and put on the emblems, and all done

[al_roethlisberger]

Another angle, still need to actually install the filler cap... it's just sitting in the hole in the photo

[Paul Minnaert]

Al,

can you see if fuel presure level is adjusable? from outside or inside?

[al_roethlisberger]

Al,

can you see if fuel presure level is adjusable? from outside or inside?

 

No, it is not... it is a fixed rate cartridge regulator much like the 2002 and earlier version.

 

The new regulator is a smaller cartridge, that appears could be changed if one wanted to, and I assume other pressure ratings are available.... but it is not inherently adjustable, nor would kits like Evoluzione's conversion kit work, as this new cartridge is much much smaller.