A new era in motocross has just been born with the inception of KTM’s 350 SX-F Motocrosser. Not since Yamaha revolutionized the way we look at motocross bikes back in 1998 with the YZ400F, has a manufacturer made such a bold move to reset the bar when it comes to a race bred and race winning machine.
The new KTM 350 SX-F has been designed and developed from scratch with 10 times world motocross champion Stefan Everts involved from the start, to lend his knowledge and experience to the project. MCNEWS was fortunate enough to receive an invitation to not only test the new 350 but share the track and also a Sydney Harbour cruise with Everts at the recent press launch of the new KTM Motocrossers. The testing took place on the new circuit in the Macarthur Motorcycle Club complex at Appin, just south of Sydney.
The 2011 KTM 350 SX-F has had a remarkable entry into the race world and currently leads the World MX1 Championship with multiple world champ Antonio Cairoli swinging off the bars. It is also currently sitting in second place in the 2010 Rockstar Motocross Nationals series domestically in the hands of Motorex KTM’s Tye Simmonds. It is nothing short of astonishing in anyone’s eyes that this bike is able to win races from the get go against factory machines whilst giving away 100cc in capacity. It is a true testament to just how good this bike really is.
When I sat on the bike for the first time on Thursday morning I was immediately impressed with just how nice this bike felt ergonomically. I was itching to get out on the track and dial the throttle on to feel what the main differences are power-wise compared to the 450 machines it has to compete with. After a short amount of time I was under no illusions as to why this bike is so competitive out of the box. It’s a weapon!
As you would expect there is not much that KTM has used from its 2010 model motocross family with this new bike. The frame is an all-new design and made from Chro-moly, not aluminum like its Japanese rivals. KTM claims that their frame is actually 0.5kg lighter than any of the competitors 450 alloy frame motocrossers and offers more space for the placement of fuel tank and other components. The main difference with the design of the new frame is the different positioning of the top shock mount and the all new linkage set up compared to previous KTM backbones. The top shock mount is further away from the frame to help isolate forces from transferring through the rear shock into frame and onto the front wheel. The PDS system KTM had utilized for so long, on some motocross and supercross tracks has now been dropped for the four-stroke SX-F models. 2011 sees the introduction of a linkage system and an all-new cast aluminum swing arm on the four-stroke motocrossers.
On the track I was pleasantly surprised with the overall handling of the new 350. The bike was set up relatively soft in motocross terms but still absorbed all the punishment that I could dish out. This included a hairy moment over-jumping a tabletop and landing on the inside mound. I had thought I may have been taking a scratched 350 back to the pits but the suspension absorbed my misjudgment no worries!
It is incredibly nimble in handling and turns with ease even on some of the off-camber flat corners that Appin has on offer. One of the most notable differences I felt when comparing the 350 engine to a 450 is on deceleration into corners. Traditionally 450s are harder to pull up on deceleration because of the rotating mass with the bigger piston (and obviously more weight) but the KTM 350 feels almost like a 250 on deceleration. This makes corner entry a whole lot easier. You can brake later and still be more in control going into the corner. This is also partly due to the engine design. In simple terms, the 350 engine is an upsized 250 not a downsized 450. It is a DOHC engine with a short stroke and weighs in at almost the same weight as the 250 engine (approx 27kgs).
KTM have also adopted a Keihin EMS (Engine Management System) with fuel injection and a 42mm throttle body does the trick at getting fire in the hull on the 350. Temperature and sea level compensation, as well as the automated cold start system, are state of the art. An optional map select switch gives the option of selecting three additional different ignition curves changing the engine characteristic. Additionally the user setting tool (available through KTM PowerParts) allows data logging and allows for laptop tuning to change the ignition (2° more advance, 10° less advance) and the EFI mapping with a few mouse clicks.
Injected motocross bikes are a dream to ride and the KTM is no different. You can be in a gear too high coming off a tight rutted corner and the injection provides a sweet smooth throttle response all the way to wide open, allowing the suspension to work more easily along the way. The engine is extremely well balanced with vey little vibration, and the only real difference I could notice to a 450 in HP was maybe a little bit high in the RPM range. The fact the 350 gets off the turns so well means that the 450s have some catch up to play by then anyway. It has great torque and its mid-range power is probably its biggest attribute. The bike pulls so strong in the middle, and in these situations I would be mistaken for thinking it was a 450!
Stopping has never been a problem on any KTM as the Brembo brakes are amazing. The lever pressure is good and the braking feel is awesome. A button start is an absolute pleasure to use, especially as the day wears on and the body gets fatigued. KTM will also release an optional kick start for the 350 as well. This will give a range of combinations to suit individual needs.
The bike also feels great in the air. Although I am no ultra-qualified pilot in the big air jumps department, the 350 felt nimble and easy to manoeuvre, and gave the impression I was riding the bike, not the bike riding me which is sometimes the feeling on the bigger bore motocrossers.
The hydraulic clutch works awesome and while it offers great feel, this doesn’t come at the expense of forearm pump. The action is so light it actually takes a bit of time to get used to just how easy it is to use. Overall you use significantly less energy to ride this 350 at a similar speed to the 450s. It was mentioned at the launch that Antonio Cairoli had the option to race either 350 or 450 for KTM this year. After much testing he decided that it was easier to ride at 100% for a 40 min moto on the 350. Aboard the 450, he had to consciously think about energy conservation to last the moto, hence why he opted for the 350. A decision that so far has paid off!
Suspension is taken care of by WP in the form of closed cartridge 48mm UDS forks with adjustable compression and rebound damping and a completely new rear shock unit with piston and bushings that provide better sealing and friction properties to handle the higher shaft velocities. The shock also has a new spring retention and preload system to allow for preload adjustment without the use of hammer and punch. Rebound, high/low speed compression damping is also standard on the new shock.
KTM have been building motorcycles for more than 55 years and in this time they have accumulated 170 world titles. I have no doubt that the KTM 350SX-F will be adding to this tally in the very near future.
– Pictorial – Images of the KTM 350 SX-F at Appin
– Video – Lapping Appin aboard the KTM 350 SX-F – DOWNLOAD (26MB WMV)