The Low Down on Big Jugs

My 4 gallon IMS tank came in and I took the bike into the shop tonight to pop on the new gas tank. I took off the original and sat'em side by each to see the differences. The 4 gal is a bit wider, the saddlebaggy lookin' parts that hang down are a bit fatter, and it's wider on top in front of the gas cap, but overall there's not a great big lot of difference.

I read some reviews where guys complained that the lower hangin' part on the rigt hand side of the big tank was lower than the other side where the petcock is. They said that since it's lower, you have to lay the bike on it's left side to transfer the fuel over. The right saddlebag of the IMS tank I have is no lower than the stocker, it's just thicker. I never really noticed much juice left in the right side of my tank when I run dry. Maybe the tank is designed so that under acceleration or during wheelies the gas sloshes to the back of the tank and is deflected to the petcock side. Anyway, my point is that I can't see how the big jug would be affected by this any worse than the stocker is.

The new jug has all the little brass nuts moulded into it just like the original so you just swap over the mushroom seat post,rubber tank strap screw,petcock, and the left side tank mount only . There's no spot for the right side mount. I can't see that you would get much extra volume by leaving out these 2 nut indents, but having only 1 mount didn't bother me. I cracked both of the tank mounts a few times crashing in the cold and rode for months before I got around to ordering new ones. The new tank fit perfectly and the sat on the bike as nice as the stocker.

I was getting a bit suspicious since it didn't look much bigger and fit perfectly so I compared volumes. I filled the stock tank with water and then dumped it into the new jug. Then I took an empty 1 US gallon antifreeze jug and filled it and topped up the IMS tank. It only held about 3/4 of a gallon more than the stock tank. I was [bleepin] glad I didn't order the 3.3 gallon jug. You'd get more extra volume by putting a couple of loops in your fuel line. Then I measured how much it took to fill and it was maybe a quart under 4 gallons. Oh well, it was a bit bigger and all shiny so I was still happy.

Then I remember reading something about stretching your tank. Since I have the new one I experimented with the old. I filled it completely full of hot water, put on the cap, and stuck an air gun (set to about 6 psi)in the vent hose and pushed the button. The tank swelled up instantly but nothing bad happened so I kept the pressure on and watched for white spots to appear in the blue plastic, but none did. I took the cap off and the water level had gone down so I topped it up and pressurized more, water more, did this a few times. Then I took the full chubby stocker and dumped it into the new jug and it almost filled it. Now I'm feeling like I wasted my money since the stock now holds the same as the new. Then I realize that it'll probably work on the new one too so I pumped that up. I was a bit more careful since I didn't want to split the thing, but got another 3/4 of a gallon into it. Took the wrinkles out of the new stickers too! If you're gonna try this you might want to bolt the tank in place first since the lower parts of the tank spread like a [bleep] in a [bleep bleep] when you pressurize and the tank mounts are nowhere near the frame. The tank shrinks back a bit right away and the fella that wrote the tip said that after a week or 2 it shrinks back almost to normal so you gotta pump it when you need it. After a while I'm sure it'll start to stay stretched, or the plastic will be so fatigued that it'll fall apart and then you have a good excuse to get a new big jug.

I noticed something about the gas caps too while I was blowing things up. The new tank came with a cap but it is a bit smaller and won't fit on the stock tank. The stock cap will fit on the new tank, it feels a bit loose until it is tightened down and then seals fine. When I pressurized the old tank the cap would hold pressure, the new cap doesn't. The new cap has a rubber baffle thing with holes in it to keep gas from splashing out. The stock cap worked like a one way valve so I took it apart to see. There is a big ball bearing that sits in a seat and a small bearing that sits in another pocket that work together to let air in but not let gas out. Take out the 3 little screws under your cap and see what I'm talking about. I don't see the point of getting a bigger tank and then loose fuel out the vent tube so I'm using the stock cap.

I bolted the new jug and rad covers on and they fit - well - just as good as the original stuff bolted to the bent rads. The new tank looks tougher so I like it even though I didn't double my range like I was hoping.

To sum it all up I'd have to say that even though the big jugs aren't all that much more useful than the small ones, they are more fun to look at. :):D :D

These links work for a while and then crap out. I reload the same link and it works again. Anybody know why? :D




Pics no worky :)

Great insight! Thanks for the post and I hope you can add the pictures soon. :)

Pic's work here.

What's the riding like up there?


A helmet cam vid clip is worth a thousand words. Mogul Riding

I recently bought a used 4 gal IMS in pretty good shape on Ebay for my DS. The only problem that I had was that it leaked around the base of the petcock. I cut a gasket out of a sheet of 1/8" N-buna rubber and that seems to have worked out well. I was curious if yours has the petcock on the left side like the stocker? That's the way mine is but the IMS website shows it on the right side. Is this a newer model? My friend has an older IMS 4gal tank on his WR400 and the petcock on his is on the right side. As a result the fuel line routing is kind of goofy. I like mine better. :)

Mine has the petcock in the factory location on the left side, and came with a rubber petcock gasket. I forgot the gasket last night so I installed the petcock with only it's original rubber. It didn't leak even when I pressurized to swell it up but I'm gonna stick the new gasket in as extra precaution.

I guess they must have changed the design from the old one. Since I bought the tank on Ebay I didn't get or know about the gasket. With my original factory o-ring seal it leaked pretty badly. No problem with the gasket. Thanks for the info.

Do you fellas know from where can I get this ems 4gal tank online?

I got mine online from Part# 180898 Price $229.99 US

I thought you were gonna give the low down on these jugs...


It just wouldn't be right to post something without firsthand knowledge of the subject, but I'm always up for a site inspection to get to the bare facts. :)

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