EXCLUSIVE LOOK INSIDE THE KTM 450SXF-FE: THE BIKE THAT ROGER DECOSTER BUILT AND RYAN DUNGEY WON FOUR AMA SUPERCROSSES ON!

June 6, 2012
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There is an inherent “Hope Gene” in every person that believes that things will get better, that tomorrow is a better day, that good things come to those who wait and that this year’s new model is better than last year’s new model. And so it goes with motocross bikes. Even when we have positive proof that a bike hasn’t gotten better?people still run out and buy that bike…because it must be better…it just must be. We demand it!

Which leads the MXA wrecking crew to the 2012 KTM 450SXF “Factory Edition” (FE). With a normal motocross bike, MXA‘s testing takes place over a long period of time (until we are satisfied that we know all there is to know), but with the KTM 450SXF-FE we thought that every KTM fan would like to see an impression of the 2012 KTM “Ryan Dungey Replica.” This is just an impression…and although it has more facts in it than most full-blown magazine tests?don’t think that this is anywhere as detailed as MXA‘s official test, but you aren’t paying for this one. It should be noted that we have also tested Ryan Dungey’s actual Supercross-winning factory bike. That test will be out in the next issue of MXA…so we do have a solid base of KTM 450SXF knowledge.

2012 KTM 450SXF FACTORY EDITION IMPRESSION

First, some disclaimers:

    (1) This isn’t a 2013 KTM 450SXF, but it a fairly accurate look into KTM’s crystal ball. The 2013 model will not have an orange frame, Red Bull graphics or several other special parts that the “Factory Edition” comes with?but it might have better stuff.

    (2) This is a procedural machine. It was designed and built to comply with the AMA homologation rule (under this rule KTM must have 400 of these bikes available by June 1, 2012). If they had failed to meet this number, Ryan Dungey would have been disqualified from every race he was in (including the four he won). Thus, KTM is selling these bikes to make Dungey’s bike legal.

    (3) This is not going to be a big production run. KTM made 400 units?actually closer to 430 units. None went to Europe, Australia and Asia. All of them came to the USA. The extra 30 will be used for testing, press, development and the race team. Why 430? Because until the 400 units are accounted for KTM can only use 8 of the production run for the race team. The 2013 production will be a large production run.

    (4) The 2013 production 450SXF will not have an orange frame (it will be gun metal gray or some other variation?but definitely not orange).

AND NOW FOR WHAT WE THOUGHT

First and foremost in the information train is that the MXA wrecking crew only rode this particular bike for one day. We had Dennis Stapleton, John Minert, Jody Weisel and Scott Williams spin laps?and they could do as many laps as the wanted. But, it started to rain midway through the day?so part of the testing was ruined by very unique weather conditions (although we kept riding). We are currently working on a more comprehensive, long-term, KTM 450SXF-FE test and have al;so ridden the works version…but this has to suffice until we are done with more intesne tetsing.

We brought a box-stock 2012 KTM 450SXF along with us to compare back-to-back with the 450SXF “Factory Edition.” This was a valuable tool in helping us understand the differences between the two bikes.

SO WHAT ARE THE DIFFERENCES?

MXA has covered the inside of Ryan Dungey’s bike very thoroughly in the past couple months, so we will brush over the technical stuff as quickly as possible, but here is a quick rundown of the differences. At the bottom of this scree, you will find detailed photos of the inner workings of the Factory Edition.

    (1) Weight. The die-cast FE engine is 4-1/2 pounds lighter than the old sand-cast engine. But some of that weight savings is lost in the transition from the old 450SXF’s Keihin FCR carb and the new bikes Keihin EFI (including a heavier magneto, throttle body, fuel pump and larger gas tank to house the fuel pump while still keeping the same basic amount of fuel on board). We didn’t weigh this KTM 450SXF Factory Edition, but KTM says that it weighs 238 pounds (which would be about five pounds lighter that the 243 pound 2012 KTM 450SXF carbureted bike).

    (2) Frame. The frame cradle is totally new (because it has to wrap around the smaller die-cast engine). However, the frame geometry is identical to the old 450SXF frame. So, really, the frame is the same in terms of performance to the previous KTM’s. This is a good thing.

    (3) Drive train. Instead of the previous, dual-cam, finger-follower drive train, the “Factory Edition” gets one cam and a pair of forked rocker arms (powering titanium Del West valves). Not only is this system simpler and lighter, but it reduces reciprocating mass.

    (4) Fuel injection.
KTM uses a Keihin 44mm throttle body. The spray nozzle is located on the bottom of the throttle body venturi because KTM feels that the fuel velocity is at its highest in that portion of the intake tract (higher velocity equals better misting). The old choke knob is now a hot start button and there is a new idle adjuster screw on the back of the throttle body.

    (5) Chassis. The 450SXF “Factory Edition” gets a new swingarm. It has a taller profile in the back half of the cast, one-piece, aluminum swingarm. Why? To make room for the new 25mm rear axle and wider axle blocks. The previous axle was 20mm. The triple clamps of the “Factory Edition” have a new lower clamp that is stronger, yet designed to tune in the flex. Additionally, the new I-beam front fender mounts with two bolts in the bottom of the triple clamp and two bolts in the front of the triple clamp. The handlebars are now special Renthal FatBars that use the TwinWall 996 bend, but are called Renthal 827 bars. They are taller than the previous Renthal 672 bars.

    (6) Suspension. Although the forks and shock come with the same spring rates as the older model, the damping has been increased to hold the forks higher in their stroke and lessen the tendency of the forks and shock to move too quickly through the midstroke. The forks on our bike have decals on them that said “Cone Valve” on them, but they aren’t KTM’s special “Cone Valve” works forks. The 400 “Factory Edition” models had the decal removed before they were delivered because KTM felt it was misleading. The “Cone Valve” decals were going to be included because those are the stickers on Ryan Dungey’s bike.

    (7) Gas cap. The squeaky wheel gets the grease and, MXA was the squeaky wheel. KTM will return to a thread-on cap in 2013. As an added plus, the threads are internal on the “Factory Edition” cap?which means that the threads aren’t on the outer edge of the gas cap, but are on the one-way air valve in the center of the gas cap. We don’t know what the advantage is?but we know that a threaded cap is much better than the locking quarter-turn cap they have been using for the last few years.

WHAT’S IT LIKE TO RIDE?


Our best comparison is to tell you how the 450SXF “Factory Edition” differs from the 2012 carbureted 450SXF.

Powerband: There is no comparison between the two engines?and that is not meant as a slam against the carbureted engine. Because of the benefits of fuel injection, higher compression and reduced rotating mass in the top-end, the “Factory Edition” rev quicker, feels lighter and is more responsive off the bottom. We had some gear ratio questions that we will need more time to analyze (and it is possible that the first batch of 540SXF-FE’s from Europe came with the wrong rear sprocket?we would expect a 52-tooth rear, but our test bike had a 50). The carbureted engine is more like a tractor, it churns and pulls and grinds out its wide powerband. It has a very broad feel, but is never snappy or light feeling.

Most MXA test riders liked the lighter feel because it was quicker at jumping on top of a gear and had less decompression braking. The old engine has its charms in that it is remarkably broad and just seems to keep on pulling, while the EFI engine snaps to attention and goes through the power quicker. For faster riders the new engine is better. For slower riders, the old engine is easier to ride because it doesn’t require much in the way of shifting.

Handling: There are only two factors that play into the difference in the handling between the carbed-equipped 450SXF and the EFI-equipped 450SXF?rotating mass and stiff suspension. Both of these factors made the “Factory Edition” feel lighter and more aggressive (even if it wasn’t much lighter and didn’t actually have any frame geometry advantages). Both bikes corner like they are on rails and were stable at speed?but the “Factory Edition” felt about ten pounds lighter.

Brakes. Great brakes…and much better than any Japanese brakes, but the “Factory Edition’s” brakes were no better than the identical 450SXF ?s brakes?because they are the same.

Suspension. Stiffer is better. The previous KTM 450SXF isn’t undersprung, but it is seriously under damped. It lacks enough midstroke compression damping on both the shock and forks?which results in the front end diving under a load and the rear end kaboinging through consecutive bumps. The “Factory Edition” suspension is significantly firmer and this pays big dividends?the front stays higher in its stroke over small and medium size bumps, which leaves more usable travel for any big stuff that follows the little stuff. We hope that KTM is willing to make the same commitment to stiffer suspension when it comes time to spec the 2013 450SXF.

THE BOTTOM LINE

This bike won four Supercross races in its first season…and was developed as a works bike that just by luck had to be produced as a production bike. We are happy about the AMA homologation rule that required this bike to be built in numbers?although the date should be changed to January 1 of the racing season instead of the idiotic March 1/June 1 dates that make no sense.

Why are we so happy about the AMA rule? Because we hate all-new ground-up motorcycle designs. First-year bikes have a track record for being flawed. We find it hard to recommend that people lay their hard-earned cash down on bikes that haven’t been fully developed (and most first-year models have teething problems). Thanks to the homologation rule and the input from Roger DeCoster and Ryan Dungey?the KTM 450SXF Factory Edition gets a leg up on the typical development cycle. We hope, as we said in the very first paragraph, that the 2013 production 450SXF is a better bike?because of the fact that the “Factory Edition” bike has been developed in the crucible of professional racing (in front of the public’s eyes).

Is this a better bike than the model that came before? Yes, not because its fuel-injected, but because it has less reciprocating mass in the engine, stiffer suspension, snappier power and a gas cap that you don’t need to be a safe cracker to break into. All of this could have been achieved with the Keihin FCR carb (and been lighter to boot)?but then you wouldn’t have bought it.


Lots to look at! The 2012 Factory Edition motocross bike features an all-new radiator wing shape, a thread-on gas cap (to replace the previous quarter-turn cap), redesigned airbox cover, orange powder-coated frame and a new gas tank (designed to house the fuel pump).


The single overhead cam valve train comes with lightened rocker arms, four titanium valves and high-performance springs. Also significant, is the simplicity of the design and the ultra-trick rollers on the rocker arms.


The compression ratio is 12.6:1, which comes courtesy of a new bridge-box piston, new ring design and a DLC-coated wrist pin.


The 2012 Factory Edition is not the 2013 model, that will come soon, but is instead a race replica of the bike that Ryan Dungey races. Under AMA rules a manufacturer must make at least 400 production bike before a factory team can race the bike and KTM has met the AMA mandated deadline. It is obvious that this AMA homologation rule is seriously flawed?but what about the AMA isn’t flawed? The rule should be 400 units by January 1 of the race season, not three months into the Supercross series.


Modern metallurgy is a wonderful thing. The 450SXF Factory Edition uses the Pankl rod right out of the works bike with a solid bearing (note the oiling grooves inside the big end for lubrication).


Ryan Dungey’s get to choose between three different sets and sizes of WP works forks. The production-based Factory Edition forks are standard-issue 48mm WP forks. The triple clamps are black anodized.


The one-piece cast swingarm has a 25mm rear axle (previous KTM’s had 20mm rear axles). The rims are black anodized Excel Dirt Stars and the hubs are CNC-machined. The orange anodized rear sprocket is by Supersprox..


Although based on the 450XC enduro engine, the actual design of the fuel injector 450SXF engine is quite a bit different in terms of piston, crank, casting and the five-speed transmission. The case bolts are 8mm hex heads, with Torx indents built in. KTM has gone to great length to protect the electronic on the Factory Edition. The significantly smaller Throttle Position Sensor (TPS) is rubber-coated and tucked in much farther than on the 2012 350SXF. Note that the starter motor now drives off of the right side of the engine. Previous 450SXF had the starter run through a transfer case on the left side. The open port in front of the 14-tooth countershaft sprocket is for the hydraulic clutch slave unit.


The front fender bolts to the leading edge of the new triple clamps.


The 2012 KTM 450SXF Factory Edition comes with Red Bull factory team graphics, orange frame, plastic frame guards, orange fork guards, orange sprocket and a gripper-style seat.


Although this Keihin throttle body may look like all others, it is actually a 44mm taper bore throttle body with a repositioned fuel injector nozzle. KTM will include the programming tool to alter the fuel and ignition maps. The software  can be downloaded from KTM’s website.


The heart of any four-stroke engine is it crankshaft. KTM spared no expense on designing a new lightweight design with careful balancing and an Formula 1-derived  Pankl rod..


The handlebars are taller Renthal 827 Fatbars (all the 2013 KTM’s will get these bars). This is a good move because no MXA test rider ever liked the low height of the previous 672 Fatbar. The red button is actually the diagnostic light for the fuel injection system.


The look of the 2012 KTM Factory Edition includes not only new radiator wings, but also a new front number plate and I-beam front fender. The front fender is flatter across the top, but still has the distinctive KTM droop nose?the deep groove down the center of the front fender is gone. Note how the front number plate plugs into the arc of the front fender.

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