(This MXA race test is from the October 2013 issue of Motocross Action Magazine).
FIRST AND FOREMOST, IS THE 2014 KTM 450SXF BETTER THAN THE 2013 450SXF?
A: Yes, but much of the credit for the improvements goes to homegrown solutions that KTM implemented.
Q: WHAT ARE THE HOMEGROWN SOLUTIONS THAT KTM PUT INTO THE 2014 MODEL?
A: Homegrown solutions are the ideas and concepts developed by local racers, hardcore KTM owners and the race teams. Here is the list.
(1) Gearing. Previous KTM 450SXFs came with 14/52 gearing. Most racers went to 14/53, but early in 2013, in an effort to get more low-to-mid oomph, there was a universal swap to 13/50, which is lower than 14/53. Just before the 2014 models were released, the Ryan Dungey Replica came with 13/50 gearing, signaling that the 2014 model would follow suit—although Ryan Dungey himself tends to favor 13/51.
(2) Clutch spring. MXA has harped on KTM’s engineers since the introduction of the Belleville washer clutch. We wanted more tension, so in 2012, MXA borrowed the stiffer clutch spring out of Ryan Dungey’s race bike. It was an instant improvement to an already good clutch. The latest Ryan Dungey Replica came with the 280 slip torque clutch spring instead of the 250 N/mm slip torque spring on the stock 2013 KTM 450SXFs. For 2014, all the 450SXFs have the stiffer clutch spring.
(3) Muffler. Last year’s KTM mufflers were odd ducks. Each model’s muffler was different. The 250SXF muffler was 40mm shorter and had a wire screen; the 350SXF muffler had an inverted, perforated ice cream cone shaped-restrictor in the muffler; and the 450SXF had two perforated ice cream cones in its muffler. MXA learned early on that using the shorter, less-restrictive 250SXF muffler improved throttle response and bark (without drastically increasing the sound). For 2014, all three KTM four-strokes come with the 250SXF muffler (40mm shorter and with a wire screen only).
Although the 2014 KTM 450SXF looks mildly updated on the spec sheet, KTM’s engineers put a lot of thought into upgrading the 2014 model. Now, if KTM’s suspension designers would work a little harder then everything would be hunky-dory.
Q: WHAT HOMEGROWN SOLUTIONS DID KTM FORGET TO PUT IN THE 2014 MODEL?
A: Local racers learn by experience and trial and error about KTM’s errors. Here are the mods they wish KTM would have borrowed from their modified bikes.
Spokes. In truth, there is nothing wrong with KTM’s spokes; We think that the rims that are suspect. Never go to the starting line without checking the spokes, especially the spoke next to the rear rim lock. Odds are good that it will be loose. If you don’t want to risk wheel failure, you can lace up the existing spokes and hubs to Excel A60 or D.I.D. rims.
Preload ring. It seems as though KTM keeps spec’ing their flawed nylon shock preload ring in spite of the fact that it was a bad idea that hasn’t gotten any better with time. When you crank the preload down on the shock spring, the nylon threads deform and seize the ring in place.
Shift lever. When the shift lever is in the stock position, it is too low, and when you move it up one notch, it is too high. We place our shift levers between two blocks on a hydraulic press and bow the middle of the shift lever to raise the tip.
Every aspect of the 2014 KTM 450SXF engine is awesome.
Air filter. Never stick the air filter into the airbox without double-checking to make sure that the filter’s back edge is sealed against the intake tract. This would be easy to fix at the factory, with a more distinctively shaped filter or a lip on the back side to notch the filter cage into.
Shift shaft. Unlike on a Japanese-built bike, KTM’s shift lever is slipped onto a tapered spline with a bolt holding it at the end of the shaft. This creates several problems. First, the tapered shift shaft gets smaller as it moves outward, which means that if the shift lever does get loose, it is on a downhill run to falling off. Second, with the bolt at the end of the tapered shaft, the rotational inertia of every downshift puts a torque load on the shift shaft, which loosens the shift-shaft bolt. Honda, Yamaha, Suzuki and Kawasaki use a straight-splined shaft with the bolt in a notch in the shift shaft. Because the bolt is at a 90-degree angle, the shift lever cannot fall off unless the shift-lever bolt falls out.
The 450SXF works best when balanced front and rear.
Q: WHAT OTHER CHANGES DID KTM MAKE TO THE 2014 ENGINE?
A: For 2014, KTM made eight changes. None of them are major, but they all add durability or usability to the powerplant.
(1) Engine cases. The 2014 center and right-side cases have had the kickstarter bosses removed. Since KTM didn’t mount a manual kickstarter on the 450SXF, the cases were doing double duty on both the SFX and EXC models (the EXCs have electric start and a kickstarter). Eliminating the bulge in the SXF cases saved 300 grams.
(2) Head gasket . KTM upgraded the sealing surfaces of the head gasket to lessen the possibility of a head-gasket leak. The new, three-layer gasket can take higher temps without faltering.
(3) Camshafts. Although the cam profiles and lifts are unchanged, the cams themselves have been lightened to lessen rotational inertia and pep up the throttle response. In addition, the auto-decompression release’s actuating arm has been beefed up.
(4) Piston pin. There were some issues with the previous piston circlips, so for 2014 the piston pin has been reshaped on the end to help keep the circlips seated.
(5) Clutch hub. The inner clutch hub has been beefed up, and, as previously stated, the Belleville washer is stiffer: 250 versus 280slip torque.
The Nylon preload ring tests our patience.
(6) Transmission. Although the transmission and gear ratios remain the same as in 2013, the profile of each gear has a new tooth geometry and finishing process to lessen nicking and gouging at the tooth ends.
(7) Mapping. The electronics for the fuel injection have been changed at the enigma level. The settings cannot be altered with the KTM programming tool or the three-way ignition maps. These super-secret enigma settings control the BOI (Beginning Of Injection), temperature sensors, and other unfathomable dots and dashes.
(8) Wiring harness. For the third year in a row, KTM upgraded the quality of the wiring, connectors and rubber boots. The wiring harness itself is shorter and rearranged into a more compact unit.
For For 2014 every KTM four-stroke will come stock is last year’s 250SXF muffler. Gone are the ice cream cone-shaped restrictors
Q: DID KTM CHANGE ANYTHING ELSE ON THE 2014 450SXF?
A: For a bike that isn’t changed very much, KTM did crank out a large number of mods.
(1) Water pump. In the past, we had issues with the water-pump seal leaking. For 2014, KTM has redesigned the cover with a deeper O-ring groove and a thicker O-ring. The 2014 water-pump cover will retrofit on older KTM 450SXFs, but only if you use the new O-ring.
(2) Seat foam. The foam core of the saddle has been reformulated to be softer initially, but not break down as quickly as the weak sisters that we’ve been sitting on for the last few years. We wish!
(3) Chain guide. The slightly smaller chain guide on the swingarm is 120 grams lighter.
(4) Gas cap. The internal threads on the gas cap have been reworked for more positive engagement, and the gas cap has a new low-profile shape; it doesn’t stick up as high as last year’s cap.
(5) Front brake. Last year it had a black reservoir and silver cap. For 2014, it has a silver reservoir and a black cap. This is just cosmetic fluff, but there are substantial changes in the lever and master-cylinder piston. The master-cylinder piston has been downsized from 10mm to 9mm.
Q: WHAT IS THE MOST SIGNIFICANT FEATURE OF THE 2014 KTM 450SXF?
A: It is definitely the powerband. KTM has dialed in the exact kind of power that the typical KTM 450SXF owner needs and wants. The powerband doesn’t have the brutal rush of the KX450F, but it can easily run with the KX450F. Plus, because of the way the power is delivered, it seems to pull twice as long as other 450s. This is the everyman 450 powerband: easy to ride down low so that it doesn’t scare you, and then faster and faster as you hold it on.
Q: HOW DOES THE 2014 450SXF RUN ON THE DYNO?
A: What we are going to tell you will be shocking. The KTM 450SXF is no longer the horsepower king of the 450 class. The 2014 Yamaha YZ450F has 58.17 horsepower compared to the KTM 450SXF’s 56.95 horsepower. The 2014 horsepower numbers are nothing to sneeze at, however, since they still beat the KX450F, RM-Z450 and CRF450 numbers.
The broad powerband allows the rider to play with the oomph.
Q: WHAT WOULD WE CHANGE ABOUT THE POWERBAND?
A: The 2014 KTM 450SXF engine is deceivingly fast. It starts out mellow and builds its power with rheostat consistency. The power allows you to go fast without the bike feeling fast. It tricks you into going fast by making it seem easy to do.
But, we have always wanted a stronger transition from low to mid. We want it to hit harder. Last year, we built a special airboot using 350SXF and 450SXF parts to mimic Ryan Dungey’s factory airboot. We opted to run a 94 dB exhaust system from DR.D that was built specifically to punch up the midrange, and we geared it down from 14/52 (a 3.714 ratio) to 13/50 (a 3.846 ratio), approximately 1-1/2 teeth lower than the then-stock 14/52.
For 2014, we can still use our hybrid airboot and midrange exhaust, but the bike now comes stock with our favorite gearing. Our Pro test riders simply copied Ryan Dungey’s 13/51 (a 3.92 ratio) gearing to get more drive, helped by the fact that they were fast enough to pull third gear all the time. Our Vet and Novice test riders were split on switching to the 51-tooth sprocket, partially because they aren’t as fast as Ryan Dungey, but mostly because they like the steady and progressive power delivery of the 50-toother.
Q: HOW DOES THE 2014 450SXF HANDLE?
A: When this bike is set up right, it is amazing. Once you work on the front-to-rear balance to get the chassis as flat as possible, it can be flicked through turns without any excess steering input. A Suzuki may turn sharper, but it shakes at speed. The KTM is the best of all worlds. It corners accurately, tracks through the rough stuff with nary a wiggle and doesn’t shake at speed. The caveat remains, however, that you have to fiddle with the fork height and the race sag to find the perfect window. Small adjustments to either end change the head angle, weight bias and feel of the bike.
Q: WHAT IS THE TRUTH ABOUT THE WP SUSPENSION?
A: KTM made some mild damping adjustments to the low-speed compression and rebound on the 2014 forks, but this is a band-aid on a mortal wound. It seems obvious to MXA that KTM tuned its suspension settings for Vet riders. In the past, we would have said that they tuned them for European riders, but the American-spec WP suspension is much stiffer than the Euro-spec stuff, which makes us wonder how bad it must be to ride this bike in Barcelona.
KTM has focused on the biggest group of 450SXF buyers—older, richer and heavier slow guys. The WP forks and shock are good for a certain speed and rider weight. Not great, but good. Any rider under KTM’s target weight or over the target speed is in trouble. When we switched from Novice and Vet test riders to Pros, they bottomed the suspension. And since the 0.50 kg/mm fork springs are Freightliner stiff, this points to insufficient damping (front and rear).
Q: WHAT DID WE HATE?
A: The hate list:
(1) Shock preload ring. “Hate” is too nice a word. Does “hassen” sound better? It’s not the design that bothers us, it is how easily it wears out.
(2) Weight. It is lighter than last year, but it is still too heavy (although not the heaviest 450).
(3) Suspension. If we were KTM and were so close to winning every 450 shootout ever printed except that our suspension kept nixing the deal, we’d put more effort into fixing the Katoom’s biggest flaw.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Brakes. Kawasaki, Honda, Yamaha and Suzuki should be ashamed.
(2) Plain bearings. Much like the old-school bronze bushings used on 1970’s road racers, KTM’s plain bearings are good engineering.
(3) Hydraulic clutch. The best clutch in motocross just got better with the addition of the stiffer Belleville washer.
(4) The bike. This bike has the best all-around handling, best brakes, best clutch, best shifting, best overall powerband, an electric starter, no-tools airbox and good durability. Other brands might have better suspension, more focused power or weigh less, but no brand has as many superlatives as KTM.
Q: WHAT DO WE REALLY THINK?
A: This is the greatest four-fifths of a motocross bike ever built. It is missing the one piece of the puzzle that would make it untouchable and that is a puzzlement. If you are a Pro who knows a suspension tuner with KTM experience or are part of KTM’s target audience, this bike is a winner.
MXA’S 2014 KTM 450SXF SETUP SPECS
This is how we set up our KTM 450SXF for racing. We offer it as a guide to help you find your own sweet spot.
WP FORK SETTINGS
The 2014 KTM 450SFX suspension works best at Vet speed. Any faster than that and it is quickly over-stressed. We have lived with these forks for many years without seeing any significant improvement in their damping. We originally blamed it on the Dutch, but a few years ago KTM moved the WP facility to Austria (and got the Dutch off the hook). It is true that KTM upped the compression damping for 2014, but that was just a baby step in the direction they need to go. We would bite the bullet and send these forks to MX-Tech, MX1 or Pro Circuit. For hardcore racing, we recommend this fork setup on the 2014 KTM 450SXF (stock specs are in parentheses):
Spring rate: 0.50 kg/mm
Oil height: 390cc
Compression: 9 clicks out (12 clicks out)
Rebound: 12 clicks out
Fork-leg height: 5mm up
Notes: If you are looking for plusher forks, lower the oil height by 10cc to 380cc. If you are faster and looking for firmer forks, raise the oil height by 10cc or 20cc (400cc or 410cc). The clickers cannot iron out the issues that Pro riders will have with these forks.
WP SHOCK SETTINGS
The shock is considerably better than the forks, but when one end of a bike doesn’t work, it transfers the bulk of the load to the other end. Until you get the forks to absorb everything thrown at them, the shock will continue to suffer. For hardcore racing, we recommend this shock setup for the 2014 KTM 450SXF (stock specs are in parentheses):
Spring rate: 5.7 kg/mm
Race sag: 100mm (105mm)
Hi-compression: 1-1/2 turns out (2 turns out)
Lo-compression: 12 clicks out
Rebound: 15 clicks out
Notes: We don’t think the average 450SXF rider will need a stiffer shock spring, unless he is over 200 pounds. Smaller riders can live with the stock spring by turning the compression clicker out.
The post TEN YEARS AGO TODAY! WHAT IT WAS LIKE TO RIDE THE 2014 KTM 450SXF FOUR-STROKE appeared first on Motocross Action Magazine.
