oFor 2009, KTM is offering two new sport quads designed for motocross. The 450SX and 505SX have a 50-inch wide wheel width, 18-inch tall rear tires, nerf bars and a kill switch, making them MX track ready. Last year’s 450 and 525XC machines were designed with the woods racer in mind. The two XC machines will remain pretty much as is for 2009.
KTM’s SX models are built identical to each other as are the XC models. This year the only differences between the two SX units are the engine displacement figures. The $11,398 450SX machine has a cylinder bore of 97mm and a stroke of 60.8mm for a 449cc reading. The $11,698 505SX has a larger cylinder bore of 100mm and stroke movement of 60.8mm for a 477cc displacement. We still do not know why KTM uses these oddball displacement engines for their open class machines. Furthermore, we don’t know why they don’t call their 477cc machine something like a 475 and their 510cc 525XC ATV a 510 or 500.
MORE ON THE NEW MOTOR
This engine is unlike the single overhead design of the XC models. The SX models use KTM’s latest DOHC, liquid-cooled, four-valve, four stroke motocross engine. It has a five-speed transmission, with no reverse. Starting is electric and a hot start lever is included for a little more help in those heated situations. When used, the hot start lever gives the engine, through the carburetor, an extra bit of air, helping a hot engine start quicker. Both of these motors have a high compression ratio of 12.5:1.
To minimize overall vehicle weight, oil cooling storage is done in the engine without a separate oil reservoir. Furthermore, a lightweight free-flowing aluminum muffler and a stainless steel exhaust system help keep weight readings low and power output high. The exhaust system still meets California sound limits of 96 dB so it is green sticker legal. Claimed dry weight for both SX models is 363 pounds.
The one complaint we had with the XC’s exhaust system is still prevalent on the SX models. You cannot completely remove or replace the stock exhaust system without removing the lower mounting bolt of the rear shock. What an unnessesary hassle!
You’ve read in our past tests of the XC models that those machines featured best-in-class suspension components. The SX models should be no different. Along the lines of Suzuki’s LT-R450 and now the Can Am DS 450X MX, these KTM’s sit low and wide.
Chromoly front A-arms give the SX models a 50-inch measurement with the right tire/wheel choice. Out back an adjustable steel axle riding in a steel swingarm can be set at 47-50 inches. For shocks on these machines, KTM went with WP products instead of the Ohlins shocks found on the XC models.
The WP shocks are high-low speed compression and rebound adjustable. The stackable dual rate spring setup features even more adjustment out of a set of crossover spacers and preload adjuster. Shocks this advanced have only been found on the machines of top racers before. Never have they been seen on production ATV’s.
To the outside of those super suspension components ride low profile, ultra tacky, 18-inch (rear) and 21-inch (front) Maxxis Razr MX tires. Not only are these some of the best performing tires on the track, they are mounted on strong, lightweight aluminum Douglas wheels featuring rolled edges.
Since these machines are designed for the track, KTM made sure you didn’t need to spend any more money on your machine before racing it. Both SX models come with aluminum nerf bars, an ignition tether kill switch and headlight cover. The only thing you will need to scrounge up on the way to the track is a number plate.
Like last year, these machines are on the pricey side. However, from bumper to grab bar, all of the KTM ATV’s have race ready, top notch components that most competitive sport ATV buyers demand and usually pay much more for through the aftermarket.
Even in narrow trim, the KTM 450 XC was at the top of our 450 shootout last year, and from the looks of it this new SX model will surpass that. Stay tuned for our first ride reviews and more shootouts in the not so distant future.
2009 KTM 505SX/450SX SPECS
Engine type Liquid-cooled, 4-valve,DOHC 4-stroke
Bore x stroke 100.0×60.8mm 97.0×60.8mm
Compression ratio 12.5:1/12.5:1
Carburetion 41mm Keihin FCR
Transmission Manual clutch 5-speed no rev
Final drive Chain
Fuel capacity 2.7 gal
Claimed dry weight 363 lb
Front Dual A-arms wprel/comp/
Rear Linkless swingarm w/prel/comp/
Front Four-piston hydraulic discs
Rear Hydraulic disc/right-foot pedal
Manufactured in Austria
Suggested retail price $11,698 (525),