REAL TESTS! 2010 MXA RACE TEST OF THE KTM 450SXF:

July 30, 2010
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Q: FIRST AND FOREMOST, IS THE 2010 KTM 450SXF BETTER THAN THE 2009 KTM 450SXF?

A: Yes. For decades KTM suffered from being too “European.” The orange bikes were tall, long and heavy. The suspension was hampered by offbeat WP suspension components and handling that was more push than turn.

No more! Over the last three years KTM has made quantum leaps with the 450SXF. Today, it is a bike with superb handling, a tremendous powerband, downsized ergos and vastly improved suspension. We like to think of it as the “Americanization” of KTM.

Q: WHAT DID KTM CHANGE ON THE 2010 KTM 450SXF ENGINE?

A: When it came to power production, KTM had no need to make any mods to their powerplant. In 2009, it made the most horsepower, revved the farthest, had the broadest powerband and was the easiest to use. This was a very good engine. But, KTM did make several significant changes to the 2010 450SXF powerplant:

(1) The crown of the piston has been reinforced with a 0.5mm-thicker piston crown for more durability.

(2) The Keihin carb finally gets a leak jet (the 450SXF has never had a leak jet).

(3) The inner diameter of the big-end rod bearing received a DLC coating for smoother action and longer wear.

(4) The titanium exhaust pipe gets a one-hole resonance chamber to lower the sound level (it should be noted that the KTM 450SXF is and was the quietest motocross bike made).

(5) The close-ratio, five-speed transmission from the 450XC model replaces last year’s four-speed gearbox.

Q: IS THE 2010 450SXF FASTER THAN THE 2009 450SXF?

A: No. Last year, the KTM 450SXF had the broadest powerband of any engine on the track. It is still as fast as it was, but, for 2010, the Kawasaki KX450F has the best low-to-mid powerband, while the KTM 450SXF has the best mid-and-up powerband.

The KTM 450SXF still holds the peak horsepower title by a slim 0.22 horsepower over the KX450F.

Q: HOW GOOD IS THE 2010 KTM 450SXF’S POWERBAND?

A: The 450SXF has a very nice powerband. It produces power that is not scary to use, but pulls across a long range. It starts out mellow. How mellow? At 6000 rpm, it gives up two horsepower to the 2010 KX450F. The KTM builds power in the middle. How much power does it build? At 7900 rpm, it blows past the KX450F to the tune of two more horsepower. It holds that advantage from 7900 rpm to 8500 rpm and then matches the KX450F pony for pony until 9800 rpm (where the KTM takes off and the KX450F signs off).

This is a deceptive powerband. It feels slow, but goes fast. The mellow low-end makes it easier to use in tight corners and bumps, while the massive gain in the middle gobbles up ground.

Numbers: Although the head angle remains unchanged, the frame, ride height, engine location and swingarm pivot have all been lowered. By welding the frame 10mm lower on the head tube, KTM was able to lower the center of gravity, crankshaft, swingarm pivot and seat height.

Q: HOW DOES THE 2010 KTM 450SXF RUN ON THE DYNO?

A: At 53.92 horsepower and 35.28 foot-pounds of torque, the KTM can claim the most peak horsepower.     

Q: WHY IS THE FIVE-SPEED TRANNY BETTER THAN THE FOUR-SPEED?

A: Choosing the right gearing on the old four-speed gearbox was always a compromise. For tight tracks, the gearing was too tall in first and second gears, but on fast tracks the gearing could be too short in fourth gear. Plus, the four-speed tranny had large gaps between each gear in order to have the same speed profile as a five-speed. All that said, we would always gear it down one tooth on the rear to perk up the transition from low to mid.

Not so with the 2010 five-speed gearbox. The five-speed is a revelation on the 450SXF! There is a gear for every occasion, and the five-speed tranny magnifies the broad KTM powerband by offering the ability to downshift without worrying about the rpm gap.

Q: WHAT CHANGES DID KTM MAKE TO THE ROLLING CHASSIS FOR 2010?

A: KTM’s engineers focused on the perceived flaws of the 2009 model’s chassis and suspension. Here is the list:

Fork offset. In the past, KTM offered all their bikes with adjustable fork offset. The owner could choose between 20mm and 18mm offset by spinning the steering stem. The only problem was that KTM’s race team was running 22mm offset triple clamps. For 2010, the 450SXF will come with a 22mm offset (and it is not reversible).

Triple clamps. Much like the 2010 Kawasaki KX450F engineers, KTM’s designers realized that their triple clamps were too rigid. The stiffness of the clamps didn’t allow the front forks to absorb energy and track across their arc. Thus, both the Kawasaki KX450F and KTM 450SXF have had more flex built into their 2010 triple clamps. KTM’s 2010 triple clamps only use two bolts on the lower clamp (it had three bolts last year). Generous milling was done on the aluminum clamps to ensure that the biting force won’t distort the fork tubes, and the steering stem has been tapered to feed in more flex.     

Forks. The 48mm WP forks get new seals and new bushings. The bushings have a concave shape so that they fit better against the fork tube surface when under a load.

Shock. The big news about the KTM rear shock is that it is 4mm shorter. When all the math is done, the shorter shock lowers the rear of the bike by 10mm (without affecting rear-wheel travel). That 10mm number is significant when mated to a yet-to-be discussed frame change. Additionally, the WP PDS shock gets completely new damping settings. In the past, KTM required the low-speed compression and rebound clickers to be turned out 20 or more clicks. For 2010, KTM has changed the taper profile of the adjuster needles to bring the clicker numbers down to ballpark settings of 12 clicks out. Low-speed damping has been increased, while high-speed damping remains about the same.

Brakes. All 2010 KTM models get new Toyo B153 brake pads. These new pads are designed to be more progressive and less grabby. The 2010 KTM 450SXF does not get the Toyo pads, but don’t worry. It gets last year’s very powerful Brembo pads, and, on the 450SXF only, they will be combined with the SXS front brake caliper from the KTM works bike. The all-new, CNC-machined SXS front brake caliper is a work of art. The rear caliper is not SXS.

Airbox. A new tray-style lip has been molded to the top of the airbox to keep water from running down on the Twin Air filter (the filter itself is smaller and narrower, but last year’s filter still fits).

Frame. The biggest and most noticeable changes to the 2010 KTM 450SXF are in the frame. Although the head angle remains unchanged, the frame, ride height, engine location and swingarm pivot have all been lowered. By leaving the head tube in place in the jig, KTM welded the frame 10mm lower on the head tube. This simple engineering fix resulted in a lower center of gravity, lower crankshaft height, more level swingarm and lower seat height. All good stuff?especially when combined with the shorter WP shock.


Squat: The 4mm shorter shock lowers the seat height 10mm.

Q: IS THE ELECTRIC STARTER WORTH THE EIGHT POUNDS OF EXTRA WEIGHT?

A: You bet. Every MXA test rider loves KTM’s electric starter. On a psychological level, it takes one of the biggest fears of big-bore four-strokes right out of the equation. You never have to worry about whether or not the KTM 450SXF will start. It will!

Q: HOW IS THE JETTING?

A: We didn’t have to change any jets on the 2010 KTM 450SXF. MXA‘s recommended jetting is as follows:
   Main: 185
   Pilot: 42
   Needle: OBDTQ
   Clip position: 6th from top
   Fuel screw: 1-3/4 turns
   Leak jet: 50
   Notes: This is the first 450SXF to get a leak jet. Leak jet and fuel screw adjustments were the only jetting changes we had to make.

Q: WHAT WERE OUR BEST FORK SETTING?

A: For hardcore racing we recommend this fork setup on the 2010 KTM 450SXF:
   Spring rate: 0.50 kg/mm
   Oil height: 365cc stock
   Compression: 8 clicks out (12 out stock)
   Rebound: 12 clicks out
   Fork leg height: 5mm up
   Note: Thanks to new seals and bushings, the amount of stiction has been reduced (previous WP forks had excessive static friction). The forks tend to dive under a load and are very touchy to fork tube height. If you think the forks dive too much, you can raise the fork oil height by 10cc (last year’s KTM had 385cc of oil in each leg) or turn the compression clicker in to eight clicks out (like we did).
 
Q: WHEN WILL KTM GO TO A SHOCK LINKAGE?

A: There is little doubt that KTM’s no-link rear suspension is not accepted by the vast majority of motorcycle consumers. The blame for this falls on KTM’s inability to get their rear suspension to work properly and the ignorance of the consumers. Scientifically, the rising rate of a single-sided, linkless shock can be identical to that of a revolving link system. Science or not, however, the average consumer believes that the lack of linkage means that the KTM doesn’t have a rising-rate leverage curve. Wrong! It has a rising rate that mimics that of a linkage system. KTM has mishandled the selection of damping, spring rates rate changes and shock angles over the last decade. Thankfully, since 2007, KTM has made major improvements to their shock settings. The rear suspension of the KTM is comparable to the rear suspension of most linkage bikes. It should be noted that not every bike with linkage is as good as KTM’s linkless system?which illustrates that it is not the system that you use, but how you set it up.

Q: IS KTM GOING TO SWITCH TO A LINKAGE SYSTEM?

A: Is KTM going to switch to a linkage system? If we were betting men, we’d say yes (and linkage system will definitely appear on the 2011 KTM 350SXF four-stroke). But, that is still just a bet for the other models. Insiders say that KTM is currently running dual test programs, with different engineering staffs (one for no-link and one for linkage). In the end, the results of these engineering exercises will determine whether or not KTM goes to a linkage system.

Q: WHAT WERE OUR BEST SHOCK SETTING?

A: For hardcore racing we recommend this shock setup for the 2010 KTM 450SXF:
   Spring rate: 7.6 kg/mm (7.2 kg/mm stock)
   Race sag: 105mm
   Hi-compression: 1-1/4 turns out
   Lo-compression: 6 clicks out (12 stock)
   Rebound: 10 clicks out (12 stock)
   Notes: Although KTM has often recommended 110mm or more of sag, for 2010 they want their shock set up at 105mm.

Q: HOW DOES THE 2010 450SXF HANDLE?

A: Over the last three years KTM’s engineers committed to a program that included a steeper head angle, different offset, better balance, lower seat height, better ergonomic riding position and a level swingarm. The result is a bike that handles very well.

This bike corners like it’s on rails, is easily adjusted by changing fork height and remains stable in the rough. KTM deserves kudos for lowering the frame. Not only does this make the bike easier to climb aboard, but it has an appreciable impact on making it feel more centered.


Works: KTM equipped the 2010 450SXF with an SXS works caliper.

Q: WHAT DID WE HATE?

A: The hate list:

(1) Lifting. There is no place to grab the KTM 450SXF, save for the hot exhaust or flexy fender.

(2) Hot start lever. The plastic hot start lever is prone to damage.

(3) Pipe guard. The burn guard melted on our bike (which is pretty funny).

(4) Side panels. Maybe it’s just us, but Job One of a side panel is to hold readable numbers. KTM’s side panels are weirdly shaped, make it hard to pick the bike up and don’t like digits.

(5) Weight. It’s heavier than we would like, but that extra tonnage is offset by the fact that it has an electric starter.As amazing as it may seem, the KTM is actually lighter than the YZ450F, RM-Z450 and KX450F. Only the CRF450 is lighter. And none of them have a battery or electric motor.

Q: WHAT DID WE LIKE?

A: The like list:

(1) Consumer complaints. Last year, the MXA wrecking crew hated the cartoon graphics, tall seat height and four-speed gearbox. For 2010, these issues have all been addressed.

(2) Handling. The KTM 450SXF corners better than many Japanese bikes (only the RM-Z450 can turn sharper).

(3) Sound. Last year, the 450SXF made a very quiet 95.4 dB. This year, thanks to the stock resonance chamber, it came in at 93.3 dB. That makes it the quietest 450 motocross bike made.

(4) Compression adjusters. Every bike should have easy-to-turn dials like the KTM. There is no need to fish a screwdriver between the bars and fork caps.

(5) E-start. Once you try it, you’ll never go back.

Q: WHAT DO WE REALLY THINK?

A: It is a fast bike that is easy to ride; a full-blown 450cc race bike that is several decibels quieter than any other bike. A big-bore four-stroke that starts with the touch of a button. It is, in every aspect, a surprisingly competent machine?one with unique twists, very few flaws and close to 54 horsepower.

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