For all of KTM’s success in the enduro world, serious growth in the fickle motocross market remains elusive. After the introduction of the new generation bikes in 2007 the Austrian maker has continued to work on improving the moto lineup and the latest version of the 450 SX-F is a pretty serious contender.
The new KTM 450 SX-F is a blend of technology from the cross country and motocross models.
Things are tough all over. Like everyone else, KTM
has had to take a hard look at its vast model line up and make some tough choices. For 2010 the XC-F line of 4-strokes is gone. The 450 and 505 were popular choices for serious racers, having the weight and power of a moto bike and only the bare minimum of off-road essentials.
The reality was that the XC-F was more or less the SX
-F with a five speed transmission. So instead of continuing with two separate lines, KTM choose to give the SX-F five cogs and consolidate the models. Completely gone this year is the 505 model.
While it may have been cutting back on the lineup, KTM has been hard at work in the R&D department. For a number of years now test riders and engineers here in the states have been hard at work to improve the handling characteristics of the orange bikes. Much of what is new this year was developed right here at our local tracks.
The 450 SX-F is steathly fast. It's going faster than it seems, but competitors will certainly take notice.
The biggest news for ‘10 is the change to the frame. The main body of the Chromoly frame is now welded to the steering head 10mm lower. This lowers the overall height and center of gravity of the 450. This change is mated to all new design triple clamps with a 22mm offset. A lower bend Renthal bar is also included to compensate for the lower seating position.
Internally the motor gets a number of updates. New piston rings are designed to eliminate oil and compression loss due to blow-by. The big end of the connecting rod gets a Diamond-Like Coating (DLC) for reduced wear, especially during cold startup. The piston also gets a thicker crown. Then, of course, the new five-speed close-ratio transmission completes the internal changes.
It looks like KTM will be the only girl at the party this year not sporting fuel injection. The good news is, as delivered, the SX-F runs great. The new addition of a leak jet to the Keihin carburetor gives super-smooth low end response. That magic starter button also helps ease the pain of not having EFI.
Europeans take the noise issue pretty seriously. Once again KTM leads the way with the “Header Pipe Resonator System.” This little closed-end canister mounted on the titanium header is for the sole purpose of reducing sound. While it looks similar to the Akrapovic factory header, it actually serves a different purpose. The muffler core is now similar to what was on the XC-F models, making for a stealthy package.
Topping off the package is a stellar front brake. The SX-F gets the shiny gold Brembo “SXS” machined caliper this year. Even by KTM standards this bike stops wonderfully. The 48mm closed chamber forks get new seals and bushings to reduce friction. The PDS shock has a larger needle and a little more valving to get more damnping early in the stroke. This extra valving means that the relatively light 7.2 n/m spring rate will be suitable for most riders.
Power delivery is smooth and strong, so there is not guess work on when it hits; it's just always there.
I got the opportunity to spin some laps at two different tracks. Glen Helen is open and rough where Pala Raceway has more jumps and tight corners with plenty of lines to choose from. As first impressions go the 2010 KTM 450 SX-F is all about the motor. It is smooth, almost too much, which makes it deceptively fast. The lack of noise contributes to this sensation.
The power delivery is very linear from the bottom all the way to the top. The spot-on carburetion pulls strongly without the clutch. There is no distinct hit anywhere in the power curve, just strong and deliberate delivery. The five-speed transmission gives a little more flexibility in gear selection. I found that often it was faster to not downshift in a corner, just a quick stab to the clutch on exit and let the strong bottom end do the work.
This year’s model comes with the Brembo hydraulic clutch master cylinder. The pull is a little stiff but the lever feel is crisper than that of the Magura model KTM has used off and on the last few years. The cure for the stiff pull is to swap to the smaller-bore KTM 125 SX master cylinder.
The changes to the frame and triple clamps amount to subtle improvements in the overall handling. A little bit of the “feel” has been taken away from the front tire so it does not provide quite as much feedback. Just a little time is needed to gain confidence in the front tire and then things are good.
The cornering is light and precise with a compact feeling. The sliding characteristics are good and predicable. This bike flat-tracks better than any previous KTM, comfortably drifting both wheels through a corner. The package seems as if it is finally able to fully exploit the benefits of the new style chassis.
No small part of that improvement is the continued development of the closed chamber fork. It is plush in just about any condition, be it little square edges or large flat landings. For that matter, the shock does equally as well. About the only place where I could get the chassis upset was in large braking bumps.
It looks like pretty much a done deal that KTM is going to a linked rear suspension in 2011, at least for the moto lineup. After riding the latest PDS settings of this bike and also the Husaberg
FX 450, I am left wondering why? The change will certainly make a huge marketing splash and perhaps that is reason enough. These bikes work really well. The stock spring rates are right in the ballpark. I rode the bike just as it was delivered, never feeling the need to play with any of the clickers.
The new triple clamp is a major change for the 2010 machine.
I have been hesitant to commit to owning a full moto bike, preferring to use an enduro bike even for track riding. However, I’ve had the opportunity to spend time on some current model MXers and I am really impressed with how much they are improving in rideability for the average weekend warrior.
My confidence level was very high riding the SX-F. On one particular jump, this was the first bike that I could clear the jump and still make the very tight inside line through the following 180-degree corner. I could brake and turn just as hard as on a 250F machine that I have been riding recently.
The changes for 2010 have made the SX-F a great motocross bike, but the new KTM 450 SX-F
could also be the ultimate off-road crossover bike. Smooth enough for enduro, just lighter, faster and more nimble. Just look at the starting line at any professional GNCC
race, there won’t be an enduro bike in sight; they are all converted motocrossers. I spent a vast amount of time last season on a 2009 450 XC-F and this bike is significantly more user-friendly.
It will be interesting to see how it stacks up against the other 450 motocross bikes
. One of the pressing questions is whether or not combining the XC-F and SX-F works as well for top-level moto guys, because this is certainly a bike that makes the average rider go faster.
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Single cylinder, liquid cooled, 4-stroke, 4-valve DOHC
Bore x stroke:
97 x 60.8mm
E-Starter/12 V 4 Ah
Keihin FCR MX 41
Wet multi-disc clutch, operated hydraulically
Central double-cradle-type 25CrMo4, aluminum subframe
WP-USD 48mm, 11.8 inches travel
WP PDS shock absorber, 13.2 inches travel
250mm disc, twin-piston Brembo caliper
220mm disc, single-piston Brembo caliper
Tank Empty Weight:
231 pounds (claimed)