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Yamaha’s YFZ450 has been a top-name ATV in the sport category since its introduction. With a 449cc engine, a lightweight steel frame, 46-inch width, and a ton of power on tap, it’s been a building platform for racers, trail riders and duners since day one. With the introduction of the fuel-injected YFZ450R and YFZ450X, the YFZ450 took a back seat. However, for 2012, it was reintroduced as a value model, with a new Mikuni BSR 42mm CV (Constant Velocity) carburetor replacing the old FCR pumper carb. Yamaha also downgraded the braking system, the handlebars and employed cheaper tires to make the cost much lower. At its introduction, it was a scant $6799—almost $2000 less than the 450R.

We have put a ton of time on the newer YFZ450, and even with downgraded components, it’s a steal. The shocks are no longer the dual-speed compression and rebound-adjustable units they once were, but they are well tuned and offer a smooth ride. We set out to put the YFZ to the test with some good aftermarket trail parts while keeping ourselves in a budget that wasn’t overly huge.


Race Tech's G3-S shock package on our YFZ worked wonders for the ride and added some ground clearance. They rode smoothly, soaked up big hits with ease and never seemed to want to bottom out.

We started off with replacing the stock YFZ’s bargain shocks with full-tilt Race Tech shocks. The G3-S shocks we chose are high- and low-speed compression and rebound adjustable. Race Tech anodized the shocks black for our YFZ, which was the all-white model. For the rear shock, they made us a custom remote-mount reservoir that bolts up behind the stock taillight. The shocks use flathead screwdrivers to tune the compression, while the rebound is a knob-style clicker. Race Tech offers many different custom options, with over 50 clicks of rebound adjustment and different needle-taper options that change the rate of adjustment when you turn in the clickers.

The preloaded setup we chose increases ground clearance over the stock suspension and offers a huge increase in bottoming resistance. The Race Tech shocks sit tall, don’t sack out when you sit on the machine, and stay up in the travel well. The feel over small bumps is plush, but when you really push the shocks hard or try to preload the suspension to get some lift over a jump or obstacle, they respond instantly. We found ourselves pumping the suspension down and then lifting to almost make the ATV bunnyhop; the Race Tech shocks are bouncy while being controlled. All in all, it’s the perfect setup for clearing trail obstacles.

The extra ground clearance almost alleviates the problem of the frame dragging on the ground. The stock shocks would let the center of the frame drag over obstacles on the trail like stumps, rocks or roots, while the preloaded RT setup would actually clear most junk on the trail. We could jump the YFZ, barrel it into corners and wheelie it over obstacles with ease.


We also installed a Barnett clutch a couple months back. It has held up to the abuse we have put the YFZ through without a single complaint.

To increase the YFZ’s bark and bite, we installed a Barker’s full-exhaust system and Power Lid to increase airflow. The Power Lid is a bored-out intake airbox lid that features increased airflow and filtering capacity, and their exhaust system is made from a mix of stainless steel and aluminum. The full-exhaust system retails for $589 and is available in a multitude of color options. The system itself installs in minutes, but you must jet the carburetor to make the machine run right. We let the experts at Fuel Customs ([909] 594-6082) handle the jetting.

The Barker's exhaust on our YFZ added a bit of horsepower and sound to the mix while shedding a few pounds of weight as well.

The Barker’s exhaust system sounds healthy and made a big difference in power. We could roll on the throttle from any rpm, and the YFZ would stand up on its rear wheels to clear anything on the trail, and the throttle response and tractability of power were excellent. Over rocks, ledges, stumps and ruts, we were able to make the YFZ leap with the combination of power and suspension mods, making it a breeze to traverse any terrain we came across. We were happy with the YFZ’s performance with just an exhaust system and jetting installed, so we didn’t dive into the motor work at all. The YFZ’s five-valve engine makes great mid- and top-end power, and coupled with the new BSR carburetor and cam tuning, it makes better bottom-end power than the old YFZ as well.


To button up the controls on the YFZ, we added a set of FasstCo’s new carbon fiber Flexx handlebars with a set of Rox Speed FX risers. Rox makes a set of handlebar risers that pivot to any angle, offering a 2-, 3.5- or 5-inch rise and mounting options for a standard 7/8- or 1 1/8-inch bar. The Flexx bars use a 1 1/8-inch mount, so instead of changing out the entire steering stem, we just installed the Rox risers. The Flexx bars are a pivoting handlebar system that alleviates harsh hits and vibrations to the hands. The new carbon fiber bars are 1 pound lighter than the aluminum set, which is quite a bit when it’s mounted at the highest point on the ATV.
The frame of the carbon Flexx bars is still aluminum, but the handles and crossbars are carbon fiber. They are thick, strong and offer far less vibration than their aluminum counterparts. We had identical-bend Flexx bars in carbon and aluminum to compare for this project, and tapping the aluminum bar would result in vibrations that the carbon bar would not transmit. As of now, the carbon bars have yet to be released to the public, but the aluminum Flexx bar kit retails for $349. Expect the carbon bars to come in right around $400.

While this seems like a huge investment for handlebars, the benefits are incredible. Less fatigue, a more comfortable ride and a cooler look all highlight the installation of the Flexx handlebars. The Rox risers are billet aluminum and stronger than they will ever need to be. Check and make sure that your cables have enough slack to install the risers beforehand; you don’t want to turn the bars and stick the throttle wide open!


To wrap up our project YFZ, we installed a Factory Effex Monster graphics kit and a new Pro Armor Bully bumper. The new Bully bumper is Pro Armor’s beefiest offering, with a replaceable bolt-on center panel for good looks and durability. The frame of the bumper is made from lightweight but strong aluminum, offering increased grab points and leverage for moving the YFZ around on the trail.

The Factory Effex graphics kit retails for $69.95. It covers most of the ATV and, coupled with the white plastic, gives the YFZ a mean look. Factory Effex vinyl is top-notch stuff, and we haven’t had any issues with their kits over the years. They fit well, look great and go on easy.


Our project trail YFZ turned out well, offering increased riding prowess on tight trails and technical sections without sacrificing its abilities on the track or in the dunes. The Race Tech shocks we had built for our YFZ are available in many different configurations, from nonadjustable to fully adjustable (as seen here). Call Race Tech at (951) 279-6655 to figure out what they can do for you. If you have rebuildable shocks, they can install Gold Valve kits and re-spring the suspension to get almost identical results that we achieved here for far less dough, which is great for your wallet!


Barker’s Exhaust    (989) 269-6921
Pro Armor    (888) 312-7667
Race Tech    (951) 279-6655
Rox Speed FX    (218) 326-1794

Topic: Machines

  • 2014 POLARIS RZR XP1000

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WARNING: Much of the action de­pict­­ed in this magazine is potentially dan­gerous. Virtually all of the riders seen in our photos are experienced ex­­perts or professionals. Do not at­tempt to duplicate any stunts that are be­­yond your own capabilities. Always wear the appropriate safety gear.
Copyright 2008 Hi-Torque Publications, Inc. All rights reserved.
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