So, with the Honda CRF450R being unleashed on a suspecting world, the KTM 520SX is no longer on the moto-thumper radar screen, right? Wrong! One good twist of the throttle will put that mangy dog to rest. You see, Honda didn?t produce a knob-ripping, arm-stretching fire-breather; it went for a laptime machine with a smooth, mellow powerband. In testing, harder-hitting motors gave better low-end, but wheelspin hurt laptimes and fatigued riders prematurely, or so the R&D guys said.
You can bet KTM did its fair share of testing, too, and that the aftermarket can get more bark out of the 520SX?if you wanted it. Muscle car fans know there?s no replacement for displacement, so why not start with the biggest, baddest motorscooter on the track, maybe the planet? That new-fangled Honda is down a full 70cc, so how can it dig trenches, clear doubles and climb cliffs like the 520SX? How come Ryan Hughes didn?t get more holeshots than John Dowd?or points, for that matter? Muscle! This here is a manly muscle machine, a Nautilus on two wheels.
KTM has come a long way (lightyears, really) in four-stroke engine development in the last 14 years. It has produced an engine that is not only fast but forgiving, not only musclebound but diplomatic. Got a little girly, 125cc-two-stroke kick? The 520SX doesn?t mind. It requires no drill or artistry with the decompression lever or sacrifices to Vishnu. Just throw a leg over the beast and kick. If it hasn?t been started in a while, reach under the tank and pull the choke knob (the hardest part) before kicking. KTM?s auto-decompressor is so effective that it doesn?t have a manual lever or a hot-start system. And still it starts. Just don?t let people twist the throttle in the pits, as the 41mm FCR Keihin has an accelerator pump and will flood at the hands of a dingus.
Once running, the Racing Four-Stroke motor shows its greatest attribute: power that?s friendly to novice and pro alike. Crack the throttle, and the awesome low-end and mid-range power make things happen in a hurry. It doesn?t have the hard hit of the Yamaha 426 or rev as freely as the Honda 450, but that next turn looms up larger and faster than with either Japanese thumper. It?s more forgiving power, too, all the way through the rev range. That quiet muffler probably chokes off some of the potential top-end ponies as well as toning down the bottom-end. Vibration is numbing at peak revs, so most folk simply short-shift the gearbox.
Gear spacing is fine for all but the tightest or loamiest tracks. Some riders prefer to swap the 48-tooth rear sprocket for a 49 or 50 to tighten up the gap between first and second for tighter courses. This was a viable mod in ?00 and ?01, but the ?02 doesn?t need it, in our opinion. Why, we haven?t a clue. Maybe the sealed cam bearing adds low-end. Anyway, GP riders can go up a tooth on the countershaft and drop to a 45 rear to attain a top speed of 90-odd mph. That?s versatile enough for our tastes.
Suspension is KTM?s greatest improvement to the 520SX for ?02. Most of the initial harshness experienced with past WP forks is eliminated with the switch to 48mm legs and the works-style cartridge. Initial action is somewhat more cushy, then the valving firms up to resist bottoming much better than last year. Damping feels light throughout the stroke. Most people will be happy with the 0.44Kg/mm fork springs, too. We also sampled the 250SX suspension this month, and the same fork struck us as harsh, choppy and unforgiving. We surmise it to be a weight and power-pulse thing; the legs are just more happy with the extra heft and fewer power strokes of the RFS. Really fast and/or big riders will probably want a revalve to hold the front end up on jump faces and such, but most of our testers were happy with the stock settings.
Out back, action is also improved over last year?s offering. The linkageless rear suspension kicks in later than before and relies more on the progressive shock spring. We ran the sag at 95-100mm. Initial action is light, allowing the rear wheel to track over the stutters well. Light damping lets the rear react to larger bumps without upsetting the chassis or rider, then the PDS throws major damping in to preventing bottoming. Tracking over ruts is much-improved over the ?01, too. Big?uns will probably want a stiffer spring, but the action is fine for most of us non-pros.
Although it?s actually not improved for this model year, much of the 520SX?s fine handling comes from its light weight (claimed 236, our nuclear-powered scales got 241 pounds with oil but no fuel) and excellent ergonomics and controls. The 520 is thin, light and fitted with Rolls Royce-grade features in a Geo Metro world. Even the brakes are powerful, with light feel at the levers. Last year we proclaimed the 520 the best motocross/off-road cross-over machine. We don?t see any reason that would change, but tune in next month to see how the open-class thumpers perform against one another.
KTM 520SX TECH/CHANGES
? New works-style fork cartridge
? Larger 48mm inverted fork w/adj. preload
? Stiffer fork valving and 0.44Kg/mm spring
? New shock w/forged body and high-low
? Stiffer swingarm with revised axle blocks
? Shock?s PDS engages later in stroke
? New clutch plates have more area
? New countershaft and water pump seals
? Sealed bearings for camshaft
Check Out The December Issue Of Dirt Bike For The Complete Test