MOTOCROSS ACTION’S 2010 KAWASAKI KX450F VS. KTM 450SXF SHOOTOUT
No offense to Honda, Suzuki, Yamaha and Husqvarna, but in last year’s 2009 450 Shootout, the Kawasaki KX450F and KTM 450SXF finished one-two. And, with a full year of R&D behind them, the MXA wrecking crew wanted to take the latest 2010 versions of the KX450F and 450SXF and shoot them out again.
Don’t confuse MXA‘s KX450F versus KTM 450SXF shootout with the full-blown, 2010 MXA 450 Shootout. This shootout only focuses on two of the highest-profile race bikes sold. We have raced these two bikes head-to-head, week-in and week-out, for months in an attempt to find the answers to the most commonly asked questions. Here is what we have learned about the 2010 KX450F and 2010 KTM 450SXF.
(1) Kawasaki. Make no mistake about it, the 2010 Kawasaki KX450F has not just the best powerband of any engine in 2010, but perhaps in the history of motocross engines. This is not an engine for the milquetoast?it rips off the bottom and keeps right on shredding muscle, sinew and dirt through the midrange. Great. Awesome. Incredible. Luscious.
(2) KTM. Don’t let our admiration for the 2010 KX450F convince you that we don’t like the KTM’s powerband. We do! In truth, the KTM actually makes more peak horsepower than the KX450F. Where the KX450F is brutish, and makes its best power on the bottom half of the curve, the KTM 450SXF is sneaky fast and makes its best power in the class from the middle on up.
HOW DO THEY RUN ON THE DYNO?
(1) KTM. The KTM 450SXF makes its best power from 7500 rpm to 11,000 rpm. The 2010 KTM 450SXF makes 53.92 horsepower at 8500. That is slightly more horsepower than the KX450F, and it occurs about 400 rpm lower in the curve. On the dyno, the KTM starts mellow and builds power as it goes. Below 7500 rpm, the Kawasaki KX450F is much more powerful, but from this point on the KTM just keeps on climbing.
(2) Kawasaki. The 2010 Kawasaki KX450F makes its best power from 5000 rpm to 7500 rpm. It is an awesome low-to-mid engine. The 2010 KX450F makes 53.76 horsepower at 8900 rpm. The KX450F’s peak horsepower is nothing to sniff at (although the KTM does pip it by a quarter horse), but it is below peak that the Kawasaki KX450F does its best work. At 6000 rpm, the KX450F makes two horses more than the KTM. At 7000 rpm, the KX-F is up 1.5 horses. Then, from 7500 rpm on, the dyno begins to favor the KTM. When it comes to over-rev and top-end power, the KTM is the winner.
WHICH ONE HANDLES THE BEST?
(1) KTM. The KTM engineers have been steadily working towards an American-style chassis. For 2010, they lowered the complete chassis, changed the triple clamp offset, shortened the shock, and made the swingarm closer to level. We love the results. This bike turns well, tracks straight and doesn’t feel like the overly tall, ungainly bike that it was last year.
(2) Kawasaki. The strange thing about the 2010 KX450F is that the Kawasaki engineers went all out to remedy the chassis’ tendency to stand up whenever the bike is leaned over on flat terrain. Not surprisingly, they did the exact same thing back in 2009. Whatever they are doing, it isn’t working. The KX450F has a tall, heavy and cranky handling frame. It doesn’t want to turn, but instead tries to stand up in the center of the corner.
WHICH 2010 BIKE HAS THE BEST SUSPENSION?
(1) KTM. KTM has proved that perseverance can win out in the end. Although the MXA test crew has bad-mouthed WP suspension components as far back as when they were named White Power, we think they have finally cracked the code. Thanks to stiff fork springs, Japanese tubes, a shorter shock and refined damping needles, the 2010 KTM 450SXF suspension is decent…better than decent?very good.
(2) Kawasaki. Kawasaki’s engineers went stiffer on both ends and added a Pro Circuit-style shock linkage to make the KX450F stay higher in its stroke and wallow less in the small stuff. It is better than in 2009, but the forks are on the firm side when it comes to damping, and the rear suspension is super-sensitive to the front/rear balance.
WHICH 2010 BIKE HAS THE BEST BRAKES?
(1) KTM. KTM has no competition when it comes to front brakes. Not only does the 2010 KTM 450SXF have very grippy brake pads, but it comes with a CNC-machined SXS brake caliper from the GP works bikes. The rear brake isn’t as grabby as it used to be and is definitely superior to the KX450F’s rear brake.
(2) Kawasaki. We always feel the need to bleed our KX450F brakes. They feel spongy when new and never really get a solid feel. For old school riders who want to run the rear brake pedal low, we have to cut some threads off the rear master cylinder’s threaded rod.
HOW WOULD THE MXA TEST CREW DESCRIBE EACH BIKE?
(1) KTM. With a powerband that never wants to quit, lower ride height, improved handling, good suspension, impressive brakes and downsized ergonomics, the personality of the KTM has changed from weird Uncle Henrik to the sweet girl next door.
(2) Kawasaki. This is a big, heavy, cranky, runaway train of a bike that is totally defined by its locomotive of an engine.
WHICH BIKE WINS THIS SHOOTOUT?
(1) KTM. When you make the most power and spread it across the widest imaginable range, you have the makings of a shootout winner. Add in sharp cornering, world-class brakes and electric start, and you are on to something. In last year’s 450 Shootout, the Kawasaki and KTM finished one-two (with the Kawasaki at the top of the chart). This year, the roles have been reversed.
(2) Kawasaki. If this were a powerband shootout, every MXA test rider would pick the KX450F’s potent low-to-mid engine. The Kawasaki’s power is so well-situated that even the slowest rider can get the most out of it. The 2010 KX450F has a great engine, but the tall gear ratios, hit-and-miss shifting, jumbo size, fragile plastic and irritating push are hard to overlook.
MXA’S RECOMMENDED KX450F SETTINGS
2010 KAWASAKI KX450F JETTING
Throttle body: Keihin 43mm
Injector size: 60 micron (at 45-degree angle)
Fuel pump/pressure: Electric/50 psi
Fuel map: Adjustable (with optional tool)
Idle: 42 clicks out
Notes: The idle clicker is the choke knob. It can be pulled out and clicked out (counter-clockwise) to increase idle speed, but really it is an air/fuel control, not an idle screw.
2010 KAWASAKI KX450F FORK SETTINGS
Spring rate: 0.48 kg/mm
Oil height: 335cc
Compression: 10 clicks out
Rebound: 12 clicks out
Fork leg height: 5mm up
Notes: The chassis is very sensitive to fork height. As a rule, we ran the forks up in the clamps until we got oversteer, then slid them down 2mm. A lighter or slower rider might benefit from lowering the stock oil height by 10mm.
2010 KAWASAKI KX450F SHOCK SETTINGS
Spring rate: 5.5 kg/mm
Race sag: 100mm
Hi-compression: 1-1/2 turns out
Lo-compression: 10 clicks out
Rebound: 10 clicks out
Notes: The 2010 KX450F is very sensitive to balance between the front and rear. Avoid the stinkbug stance.
MXA’S RECOMMENDED KTM 450SXF SETTINGS
2010 KTM 450SXF JETTING
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. Fuel screw adjustments were the only jetting changes we had to make.
2010 KTM 450SXF FORK SETTINGS
Spring rate: 0.50 kg/mm
Oil height: 365cc stock
Compression: 8 clicks out
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 suffered from excessive static friction. 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).
2010 KTM 450SXF SHOCK SETTINGS
Spring rate: 7.6 kg/mm (7.2 kg/mm stock)
Race sag: 105mm
Hi-compression: 1-1/4 turns out
Lo-compression: 12 clicks out
Rebound: 10 clicks out
Notes: Although KTM has often recommended 110mm or more sag, for 2010 they want their shock set up at 105mm. If you are over 175 pounds, switch to the stiffer 7.6 kg/mm spring.