2009 KTM 450 SX ATV Review

KTM makes a wicked ATV motocross machine in the 450 SX, but we tapped Hinson Clutch Components to help us make it even better.

Being the most expensive of anything in the powersports industry is a dubious title. KTM is known for costing a little more off the showroom floor than other ATV and motorcycles. But the distinction of being one of the most expensive mainstream manufacturers doesn’t stem solely from its European roots. The 2009 KTM 450 SX quad is a perfect example of how the Austrian company puts extra features on its machines which justify the cost. However, even the 450 SX isn’t a perfect sport ATV in stock form, and so we enlisted Hinson Clutch Components to guide us through some simple upgrades to make this bike the competitive race winner it wants to be.

Former professional ATV racer and the man behind operations at Hinson Clutch Components, Bryan Hinson knows better than anyone the benefits of his family's products. One of the biggest issues with ATV motocross racing comes in the abusive form of braking bumps. Deceleration chop is bad enough for dirt bikes, but quads have twice as many wheels and the contact patches are much larger. That translates to a big problem when corner entries or steep downhills get hammered out. The solution is Hinson’s BTL (back torque limiting) clutch kit. We all know them as slipper clutches, but while you might assume that only supermoto guys would be interested in this type of product, think again.

The Hinson BTL clutch kit was the
favorite upgrade for our testers.

“The advantages to that,” says Hinson of the BTL, “is that when you’re coming downhill or into corners it allows the rear wheels to freewheel more.” Our testers noted that the difference was huge as they bombed down the notoriously steep hills of Glen Helen Raceway. Not only did the rear end resist kicking around, but riders were able to attack the descents and the following corners with greater speed, not to mention increased confidence and less rider fatigue. The BTL kit is designed to work with stock fiber and steel clutch plates and comes ready to install, but Hinson went ahead and included their own clutch pack for the test.

With strong, tractable power, the 450 SX doesn’t typically require much abuse on the hydraulic Magura clutch. However, a Hinson clutch basket was installed which features several benefits to keep the all-important system working at a premium and add lifespan. Hinson claims that the billet aluminum basket spins truer than stock components which minimizes heat buildup – a clutch’s mortal enemy. In addition to the tighter tolerances, slots in the basket fingers allow increased oil flow which also keeps down heat and maximizes lubrication. Everyone likes to show off their upgrades, but that isn’t possible with internal components, so to do our modded ATV some justice a Hinson clutch cover was bolted on to represent.

With the smooth tracking and extra speed carried into corners, courtesy of the BTL, massive power from the dual four-piston fixed calipers and 180mm wave rotors become more of a necessity. Out back is a 200mm disc pinched by a single-piston binder. “The front brakes on that have the most stopping power of any ATV I’ve ever felt in my life,” says Motorcycle USA ATV test rider and photographer Adam Campbell, including his former race bikes with oversized components. “If you’re not careful it will put you over the bars and I don’t think I’ve ever said that about any other ATV.”

KTM manufactures a mounting position on the 450 SX right from the factory. This means that not putting one on your ATV is simply foolish.

Impressive brakes were a complement to the front end work. With the rear end under control and pushing the sport ATV to new limits, it was important to get the front sorted out as well. The first order of business was a Scotts Steering Damper. KTM obviously knows the advantages of steering dampers and the ATV comes from the factory ready for one to be installed with a pre-made mount. KTM’s extensive PowerParts catalog includes the Scotts Damper which is known in motorcycle and ATV circles as being one of the best aftermarket upgrades possible. MotoUSA testers were able to ride harder, longer and with more precision thanks to the high/low-speed circuits inside the damper. The Scotts unit only applies valving when the bars are moving away from center, which means it doesn’t require a lot of rider input. Though the 450 has a wide, stable stance to begin with, the damper eliminated any headshake as the track roughened up and kept the bars from transferring unexpected impacts.

On the subject of impact absorption, the KTM 450 SX comes with some impressive WP suspension, but we opted to pick up a set of Fox Racing Shox’s top-shelf springs. I take that back, the front shocks don’t actually use springs at all, at least not in the traditional sense. A small internal compression spring controls valve stacks, but the pair of Float X Evol components utilizes two external air chambers to control damping. The standard reservoir at the top of the shock is referred to as the main chamber. This allows adjustment of the preload, or ride height. The shocks are adjustable for high/low-speed compression and rebound. Our testers praised the Fox’s ability to tailor the front end and minimize body roll by keeping things lowered. The EVOL (extra volume) chamber is what manages the shocks when bottoming out. Adding or releasing pressure has the same effect as changing main springs on standard coil-over format. Campbell was especially impressed with a lack of binding and smooth action through the entire stroke devoid of harsh spots. The air technology keeps weight to a minimum which subtracts from the claimed 364 tank-empty pounds.

The FMF Factory 4.1 exhaust muffler gave the 450 SX some extra bark. The other upgrades made it easier to ride so managing the power was much less fatiguing.

A Fox Shox Podium X unit graced the back end. Unlike the radical fronts, this is more traditional with a spring and oil shock using a 47mm steel body and remote reservoir. It too is adjustable for preload and has speed-sensitive rebound and high/low-speed compression. All of our suspension was ordered with an expert/pro-level rider in mind.

The KTM 450 SX is made to go forward, and only forward since the five-speed transmission lacks a reverse. The stock aluminum muffler with spark arrestor was swapped out for an aftermarket slip-on unit. Following the KTM race team’s lead, a FMF Factory 4.1 can was bolted in place and the boost in reactive power was noticeable. “It has so much power (stock) it’s ridiculous,” grins Campbell. “All we did was put a FMF silencer on there and honestly I couldn’t imagine doing any porting or other work to that motor in order to race it. It was already a handful. In some situations it almost felt like it was a little too much, but it was a lot of fun to ride.”

Hinson mirrored the statement, commenting that although it sometimes takes more energy to control the instant surge, it also has exceptional benefits depending on the particular situation. “It was really good,” he says. “It was fun to ride, predictable. It definitely wanted to track harder than some of the other bikes which made it really fun to ride. I was impressed.” Fortunately, the 450 SX comes with Maxxis Razr MX tires, considered some of the best motocross ATV tires on the market, and we found them up to the task of transforming hard-hitting power into forward momentum. He also credited the chromoly chassis and swingarm with excellent balance and power transfer to the ground.

At $11,398 from the showroom, the 450 SX is several thousand dollars more than its competition to begin with. But with stock items like a skidplate, perfect-fitting nerf bars, beefy aluminum steering stem, wired-in tether switch, unbreakable folding levers, steel-braided brake lines, headlight eliminator plastic, adjustable ECU mapping and aluminum beadlock wheels, the KTM 450 SX has a lot to offer. The extra $4100 in aftermarkets to create our test version only adds to the expense list, but this quad is for the serious racer. Though its pricetag is getting close to a full-blown race quad, the Hinson Clutch Components project KTM has the added benefit of reliability that comes with leaving the motor untouched - a very valuable attribute. The symbiotic action between the Scotts damper and Fox Shox up front and the

A few high-dollar upgrades are necessary for any sport ATV to make it truly competitive, but the KTM 450 SX really comes alive. Our testers think this bike could win at almost any level.

BTL clutch and Podium X rear shock make this package extremely well-rounded. Unless you plan to compete at a very high level, the stock KTM or other sport ATV machines might be more appropriate. However, according to our testers, this one was worth every cent.