Installing a Larger Tank on the Yamaha WR450F

in howto, test


The WR450 comes stock with a 2.1 gallon fuel tank. This is fine if you're going to be doing hare scrambles or enduros with short stages and happen to have a decent support crew with extra fuel available. For those of you who want to go exploring or attend dual sport or adventure rides on your WR, you are out of luck with the stock tank. I was able to travel 50 miles maximum in the woods with the WR using the stock tank. I even tried commuting to work with it and only got about 65 miles before I had to refuel. You'll get about 1.6 gallons before you have to switch to reserve. It is just begging for a larger fuel tank. Rant mode on. Given the trend of the newer fuel injected off road machines to use a 2 gallon tank, I suspect the aftermarket industry will explode with alternative fuel storage solutions. It's too bad the major manufacturers are ignoring the majority of buyers. They actually think the majority of buyers are buying these bikes to race them, when in reality, the majority of purchasers are people who want to use them for recreation. Yes, marketing a thoroughbred race bike gains bonus points, but does limiting the stock fuel capacity to 2 gallons make any kind of sense at all? Figure your average recreational rider will ride for 3 hours. Then figure how much fuel the bike you are trying to sell them will use. Now, you have a realistic real world solution to your fueling strategy. Modern off road bikes should come with a minimum of a 3 gallon tank. Rant mode off.

Next up? I install a 3.6 gallon Clarke tank to replace the effeminate 2.1 gallon stocker.

The kit arrived in a plain a cardboard box. The only thing in the box besides the tank and fuel cap were two washers and a gasket.


The tank was actually full of saw dust and some kind of blue epoxy looking residue. I rinsed it out with soap and water and tried to pick and prod to release all the loose bits I could before proceeding with the install. The area where the fuel petcock was to be mounted was also rather ragged looking. There were loose bits of plastic hanging free that I decided to remove. I didn't want to risk them coming loose of their own accord and getting stuck in the fuel filter that is attached to the petcock.


Once the tank is clean, you may proceed. Remove the seat. There are two bolts that hold seat on. They are located towards the rear of the seat just above the number plates.


Next, remove 4 bolts from each of the radiator scoops attached to the tank.


This is what you should see now.



Make sure the fuel petcock is in the off position.


Locate the fuel hose that runs from the petcock to the carb. Remove the hose from the carb.


Remove the rear tank bolt.


Remove the front tank bolt.


Here are the two tanks side by side. You can easily see that the 3.6 gallon dwarfs the emasculate 2.1 gallon tank.


If your old tank contain fuel, you have two options. Drain it into an intermediate fuel container or dump the fuel from the old tank directly into the new tank. Being one to never pass up a short cut, I opted to dump the fuel from the old tank directly into the new one. The problem was, I needed to remove the petcock from the old tank and install it on the new one. I found that if you have a decent cap with a vent where the check valve operates properly, you can simply dump it upside down with no leakage. I stacked some tires up and used those to hold the upside down tank while I removed the fuel petcock.


Mount the old petcock onto the new tank facing backwards. Yep, you have three choices. You can mount the petcock facing backwards and use the stock hose to connect it to the carb. Or you can mount it facing the correct way and use an unweildingly long piece of hose the you supply. Or you can opt to buy a petcock from an earlier WR that will face the correct way. Make sure to use the included gasket along with the stock rubber o-ring. If your tank didn't come with a gasket, you need one. You can't use the stock o-ring without the Clarke rubber gasket. If you do, it will leak. If your tank didn't come with a gasket, contact Clarke and make sure they didn't make a mistake by not including it.


Once the petcock is installed, mount the tank on the bike and measure the stock hose. You can trim the stock hose and use it if you've mounted the petcock backwards with the valve facing the engine. Measure it, then snip off the excess bit.


I don't have any pics of this next bit because it was a pain in the ass frankly. I found the rear bolt easy to install on the Clarke tank. The front bolt was not so much fun. The angle of the front mount hole on the Clarke tank is completely wrong. You have to push the top of the front bolt so far forward and put so much pressure on the rubber grommet that Clarke includes with the tank that it is incredibly difficult to even get the bolt started in the threads properly. In fact, I hate to admit it, but I ended up cross threading it twice before I got it right. Next time I take it apart I'm going to chase the threads in the hole or else weld it up and tap it again. Really Clarke, this is shoddy work. You need to get that front angle right. My guess is they've retained the angle from the 2006 and earlier frames and not bothered to modify the mold to fit the later frames. So take care installing the front tank mount bolt. The rear goes on just fine.


Once the tank is mounted, fill it up before you put the shrouds back on and make sure it doesn't leak. Take it for a ride without the shrouds just to make sure. You don't want to stash the bike safely away in your basement garage with a leaky tank do you? Take the time, make sure.


Congratulations, You've just installed a real man sized fuel tank on your WR450. Enjoy!


If this article helped you, feel free to return the favor and use this link if you want to buy a
Clarke Fuel Tank at Motorcycle-Superstore.

Or, use the ad at the top of the page any time you want to purchase from

Update: April 21, 2012

After riding the WR with the new tank I have a few observations to report. First, the tank is a bit wider than stock. Actual measurements make it about 2.5" wider. But, it feels much wider than that. In fact, it's now wider than the tank on an RC51 measured at the front. The tank itself isn't that wide, but with the radiator shrouds bolted to it, it is. This will take some getting used to, but it is only a mild annoyance compared to the effects on handling. Yes, adding an additional 20 pounds of fuel to the front of the bike has thrown the already marginal at best suspension of the stock WR into total mayhem. The WR with stock suspension has always felt like the front was under sprung and the rear was over sprung. With the addition of 20 pounds biased heavily towards the front, things have gone horribly pear shaped. The WR now feels like one of those early 60s delivery vans where the cab is placed in front of the front wheels. It wallows horribly in sweeping turns and unless you wheelie through rock gardens, it plows in and bottoms heavily like a drunken Amish man driving a John Deere tractor through NY city. In other words.. totally out of place. So, I have decided to turn this into a project. I've jumped on the internets and ordered up some stiffer springs and some shims to adjust the valving. I'll report back once the adjustments are complete.

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