Despite being an omnipresent force in the realm of off-road motorcycles, KTM and its 450 SX-F motocross bike have struggled to find the same success on the motocross and Supercross tracks compared to its Japanese counterparts. Having never swung a leg over a KTM 450 SX-F during our 450 Motocross comparisons, we didn’t know exactly what to expect from the Orange machine.
The first difference obvious difference with the SX-F is that it still uses a carburetor. It’s the only 450 in this comparison still making use of the old, but reliable, mechanical fuel/air mixer. The second key difference is that is the only machine not employing a conventional link-type rear suspension, instead having the shock mounted directly to the swingarm. Look beneath the surface, however, and one learns that there are many more subtle differences that make KTM’s motorcycles stand out from the rest.
Race-specific goodies including wave-style braking discs, blacked-out wheels, triple clamps, and frame are abundant. Additional proprietary hardware comes in the form of a quarter-turn fuel cap, sealed steering head and axle nuts, plus a maintenance friendly tool-less airbox. We also appreciated how easily it is to adjust the rear shock preload with the simple aluminum collar and the easy tool-less compression damping adjusters atop of each fork leg.
The SX-F is the only 450 in this test to still use a carburetor. It worked great with spot-on throttle response at Racetown 395.
Hop aboard the KTM and feel how its cockpit is roomy and unencumbered. It offers the same type of free-roaming space as the Kawasaki, and possibly a tad bit more. Similar to the KX-F and CRF, the KTM uses a Renthal handlebar, though the Austrians opt for the crossbar-less Fatbar model. Reversible bar mounts give the rider the opportunity to move the bars forward slightly and short and tall riders alike noted its comfortable layout. None of our testers expressed any concerns with maneuvering their bodies at speed.
Glance down at the handlebar and you’ll see a tiny black electric start button. KTM has done away with a conventional kick start lever, instead opting for the simplicity of e-start – and we love it! Obviously, the KTM is the easiest to light whether the engine is hot or cold, and even after a tip-over or stall. We wish the rest of the 450 motocross bikes could offer the same.
Pin the throttle and the KTM’s engine doles out a ridiculously flat spread of power, and we mean that in the best way. Despite not employing electronic fuel-injection and instead relying on a Keihin FCR 41 carburetor, jetting and throttle response were spot-on in the high desert elevation at Racetown.
Initially, bottom-to-mid power feels the mellowest even compared to the Honda and Yamaha, but as the revs increase the KTM comes alive pumping out the most power for about 1000 revs before the Kawasaki takes over. Keep your wrist locked and where the EFI bikes are stalling out, the KTM just keeps pulling all the way to the rev limiter with class-leading top end.
Look at the results from the holeshot test. Despite finishing behind all but the Kawasaki, the KTM recorded the highest trap speed (nearly 52 mph), signaling how potent the upper reaches of its powerband are. In the third gear roll-on test, despite recording the slowest time, it posted the second-highest trap speed (49.51 mph). It’s this kind of engine versatility that won the hearts of our testers in the motor department.
“The KTM possessed my favorite power delivery by a long shot,” says Milan. “The bike feels like a tractor. It just pulls right from the bottom and smoothly builds to an incredibly powerful mid-range followed by a Top Fuel dragster top end! I could enter corners a gear high or a gear low and still come out strong on the other end. The incredibly powerful, yet friendly nature of this motor was confidence inspiring plus it felt hooked up everywhere.”
“The KTM was the surprise of the day,” adds Sciacqua. “It’s got the easiest power delivery by far and is totally controllable exiting turns. It really did surprise me. The power delivery to the ground is amazing. As your exiting the turn it just hooks up better than any other bike.”
Equally impressive is just how quiet the KTM is even under full throttle, due in part to its innovative Header Pipe Resonator System. The system is comprised of a small metal canister that attaches to the titanium header pipe and reduces exhaust noise without compromising overall engine performance.
For ‘10 KTM engineers added an extra transmission cog and the new five-speed was well-received by our testers. Out on track the KTM never feels like it’s between gears. Overall gear ratios felt similar to the Honda and action through the shift lever was positive. The KTM also has the distinction of being the only bike to offer a hydraulic clutch as opposed to the cable actuated components on the Japanese bikes. This substantially increases the level of feel during race starts or any other situations which warrants fanning the clutch. Another benefit is its resistance to fade during prolonged use.
Despite employing e-start, and all the things that go with it including a battery and an electric starter motor, not to mention carrying the biggest fuel load (2.2 gallons), the KTM weighs less than both the Kawasaki and Yamaha at 249 lbs with a full tank of gas.
As mentioned before, even though the KTM certainly has some size to it, its lively handling manners are one of its strongest attributes. Riders had no issues placing the bike where it needed to be – even super tight inside ruts weren’t a problem for the Orange machine. Furthermore its dexterity doesn’t come at the price of stability. Straight up, you won’t find a more solid mount, even compared to the ultra-stable Kawasaki.
“The KTM felt practically glued to the ground,” says Milan. “I’m sure the engine’s power delivery aided in the predictable feel…The bike tracked straight and would hug the inside line on the tightest of corners,” he continues. “But where the KTM really shined was in the whoops. The only complaint I had regarding the suspension was in the bottoming control. The KTM had the most ‘metal on metal’ feel when bottoming out.”
While Milan’s extra weight taxed the capabilities of the suspension, featherweight McElroy had this to say about the KTM’s WP combination:
“The KTM has the best fork out of any bike I’ve ever ridden. The front end is always stuck to the ground and soaks up all the bumps. The rear end tracks well but it doesn’t have the most plush feel. The shock stroke was a little harsh, but it was one of the better bikes through whoops.”
“The suspension was a little stiff for me,” says Armstrong. “I noticed it mostly in the small chop, braking bumps and acceleration bumps.”
The KTM continued to impress with its braking prowess. Who knew dirt bike brakes could be this good? The Austrians’ use of the Brembo braking system is head and shoulders above the competition. The level of feel at both levers borderlines on insanity – in a good way – allowing you to trail the brakes into corners with the most confidence of any bike.
The 450 SX-F is a serious strike against the best from Japan. The engine is smooth, quiet and powerful, plus starting it is as easy as pushing a button. Its chassis is nimble in the tight stuff and unflappable through fast, rough terrain plus the ergos are a match to almost all riders.