Comparison of the Clarke and IMS oversize tanks for the '06+ YZF

4 replies to this topic
  • grayracer513

Posted July 05, 2008 - 03:30 PM


I've had a Clarke 2.6 gallon tank on both of my '06 YZ450's for some time, now. The tank actually holds 2.8 gallons, and is pretty slim and unobtrusive for as much larger it is than the stock one. But there were things I didn't like about the fit on the bike, and I kind of wanted the extra half gallon the IMS offers. I just didn't want it $300 worth.

But the chance came to pick one up used, so I went for it. This gave me the opportunity to directly compare the two as to fit and ease of installation.

The Clarke is difficult to mount. The problem is that the mounting holes are about 5mm too far apart, and once one bolt is in, the other can be very difficult to get threaded, sometimes requiring the help of an assistant to push the tank into place. The front mount point uses a sleeved grommet in a cast hole at the front of the tank, while the rear uses the same grommet in a slot. The slot is long enough to cover any reasonable production variance, but the farthest forward position of the grommet is still to far back in relation to the front hole on both of my bikes. Add to this that the fit over the frame seems to interfere with trying to reposition thre tank to align the bolt in the front. This is enough of a hassle, particularly with a steering damper mount involved, to cause me to procrastinate or avoid pulling the tank for some services.

The shrouds also don't blend into the tank as they should. This post shows that:

Otherwise, the seat fits on the bike well with the Clarke mounted, and requires only a little extra downward force to engage the center hook.

The Clarke comes with embedded blind nuts for a petcock on both sides, although the holes for the fuel ports are not drilled (they are clearly dimpled, and easily drilled). This gives you the option of having one on either or both sides, which I like. I set mine up with two.

The IMS bolts up as easily as the stock tank. The front of the tank extends forward over the mount hole in the frame, so they provide a neat little bracket that bolts to the frame first, then the tank fits onto that. The rear is anchored by the rear bracket from the stock tank. The tank fits beautifully over the frame, and clears everything without the additional pads the Clarke needs.

The shrouds blend nicely into the tank sides, but they sit too far back to connect to the radiators with the original bolts. Mine came with no longer bolts or spacers, so I rigged some up, bolted the shrouds first to the radiators, then pulled them back into place on the tank without much trouble. I'll be refining the fit at that point some more.

The IMS comes fitted for one petcock only, and no crossover line. The bottom of the tank on the right side isn't flat enough to fit one, so I'll have to do without, but it doesn't look like it will isolate very much fuel on that side, anyway.

The seat was another matter. The tank pin engaged easily enough, as did the center hook, but the seat did not want to slide far enough forward to line the seat bolts up. It took quite a bit of effort striking the back of the seat with the heel of my hand to get it finally line up. The point of interference seems to be that the edge of the seat pan at the lower rear edge of the gas tank comes in contact with the tank, and resists sliding the seat further. Now that it's been on the bike a while, it goes back on somewhat easier, but the angle and shape of the seat mating face of the tank is a little off.

In all, I think the IMS is a better tank than the Clarke. It's bigger, fits better, and looks more finished. It clears the engine, frame, and radiators better, and hides less of the engine. But it's more expensive, too, at a retail of something like $280 vs. $190 for the Clarke, so you could argue that both are an equal value. The Clarke does a good job at a lower price, but the IMS is a bit nicer.

Here's the IMS in black on another YZ:

  • AZ Thumpdaddy

Posted July 06, 2008 - 05:23 AM


Gray - Good write up. I bought an IMS for my 07 after doing research here on TT. I had the same problem with the shrouds and the seat that you have described and had to stretch/push them to fit. I am pretty sure that they will relax into place as time goes by. I went with the petcock from an 05 so that it is facing outwards. What impressed me the most was how narrow it was close to the seat, almost as if the stock tank was on. My son has a YZ250 with the IMS 3.2 and it is wider in the seat area than my 450. I have used Clarke tanks in the past on a CRF450 and an XR650 and they fit and looked well on those bikes with no fit issues. What helped me decide was the pictures on TT showing the differences of how the shrouds fit on each and that the Clarke covers up more of the engine area. I am also using it with a Scotts under bar mount (submount), Applied triple clamps, and WC rad cages with no fit problems.

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  • SXP

Posted July 06, 2008 - 05:10 PM


Gray - Raise the rear post/knob off the tank with a ~ 1/8" spacer (or use a larger nut (than the bolt) as a spacer under the knob) and the seat should slide on just fine. Ran into this same problem 1.5 years ago when I put the IMS on my 07 WR.

  • grayracer513

Posted July 06, 2008 - 05:53 PM


Gray - Raise the rear post/knob off the tank with a ~ 1/8" spacer (or use a larger nut (than the bolt) as a spacer under the knob) and the seat should slide on just fine. Ran into this same problem 1.5 years ago when I put the IMS on my 07 WR.

You mean the seat mounting peg that screws onto the tank? That might work.

  • SXP

Posted July 06, 2008 - 06:32 PM


You mean the seat mounting peg that screws onto the tank? That might work.

That thingamajig!

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