2020 KTM 450SXF MXA FULL REVIEW
Q: FIRST AND FOREMOST, IS THE 2020 KTM 450SXF BETTER THAN THE 2019 450SXF?
A: Yes, but it should be noted that we are comparing the 2020 production 450SXF against the 2019 production bike. We are not considering the 2019-1/2 KTM 450SXF Factory Edition in this comparison because, for all intents and purposes, it is a 2020 450SXF (and we know that the 2020 production model is an improved version of the Factory Edition). Yes, the 2020 KTM 450SXF is better than the 2019 KTM 450SXF, and here is a complete set of reasons why—and, in some cases, why not.
Q: HOW DOES THE 2020 KTM 450SXF RUN ON THE DYNO?
A: There was not a spot on the 2020 KTM 450SXF dyno curve where it did not beat the 2019 engine. It only beat it by about a horse or two at every rpm setting, but spread over 11,400 rpm, that one horse gets magnified. It is important to note that KTM has changed its engine philosophy from a few years ago. KTM used to build 60-horsepower 450SXFs, but KTM realized that it’s more important where the power is than how much there is. The 2020 KTM 450SXF has the broadest range of power‚ with the most horsepower in the midrange (6500 rpm to 9300 rpm) of all the 2020 450s. Peak horsepower is 58.32 horses at 8800 rpm.
Q: HAS KTM ADDRESSED THE MAP ISSUES THAT MXA COMPLAINED ABOUT LAST YEAR?
A: Last year the MXA test crew was part of an Austrian-run map test session that started when we insisted that Jamie Ellis from Twisted Development had a crisper and more responsive map than either Map 1 or Map 2 in the stock 2019 KTM 450SXF. The American KTM test team expressed an interest in coming up with a crisper and more responsive map. KTM Austria was willing to listen and, in fact, sent a team of engineers over to SoCal to test maps with select groups of American test riders, including the MXA wrecking crew. After the test, all five test riders insisted that there was one map that was significantly better than the existing KTM maps.
The test riders were convinced, but the Austrians weren’t. The Mattighofen engineers claimed that the so-called “American map” was too aggressive for European riders and they couldn’t put it in the bike. But, they conceded that they would keep the map they currently had as Map 1 and perhaps use the American map as Map 2 (normally called the “aggressive” map). MXA was happy with that compromise because we didn’t care what button we pushed as long as we got a snappier and more responsive map, especially from low to mid; however, it didn’t happen that way. Instead, Map 2 on the 2020 KTM is a watered-down version of the American map. It does make a significant difference over the stock 2019 map, but we’d still rather have the “American map” in the 2020 ECU. However, when combined with some other 2020 engine modifications, it is an improvement.
MXA suggests that if you want more power, you should send your black box to Twisted Development and have them put their map in place of the milquetoast Map 2 that the KTM engineers compromised on. You can reach Twisted Development at www.td-racing.com or by calling (951) 698-7222.
Q: DOES KTM HAVE ANY TRICKS IN THE 2020 ENGINE THAT NO ONE KNOWS ABOUT?
A: Yes. There are two pieces of electronic wizardry that aren’t new, but few people paid attention when they were introduced on the 2019 model.
(1) IG-ACC is an electronic map feature that advances the ignition timing above and beyond where it would ever be in normal riding. IG-ACC only comes into effect when the throttle goes from closed to open. By advancing the ignition timing every time you turn the throttle from closed to open, you get an added boost of juice.
(2) Split injection was put into KTM’s fuel injection system in 2019. It is similar to Honda’s Dual-Timing injection system from 2014. Split Injection breaks the long burst of fuel spraying out of the injector nozzles into two halves. The first short-duration spray cools the back of the intake valves, so the following long-duration spritz has a denser air/fuel mixture to work in. This results in more usable power across the midrange.
Q: WHY DID KTM COME OUT WITH A VENTED AIRBOX COVER?
A: Consider the vented 2020 KTM airbox cover a victory for backyard engineers, shade-tree tuners and inventive local racers everywhere. Over the years, the MXA test riders made the KTM R&D department ride with the stock airbox cover and without the airbox cover to prove how restrictive their airbox was. Opening up the 2019 KTM 450SXF airbox with a drill produced a noticeable increase in throttle response and rate of acceleration in the midrange. KTM’s American test department fought with the Austrian engineers to put air vent holes in the stock 2020 airbox cover. It was a no-brainer. For 2020, each KTM four-stroke will come with two airbox covers, the all-weather old one and the new vented one.
We know the vented airbox works on the track and is more noticeable than the dyno numbers suggest; however, to convince KTM that it worked we had to prove it on the dyno. At 9000 rpm, it was 0.25 horsepower better. At 10,000 rpm, it was 1 horsepower better. At 11,000 rpm, it was 1.1 horsepower better, and at peak it was 1 horsepower better. Torque was up 0.5 pound-feet across the board. But the difference is in how the power feels. It is noticeably better with the vented airbox.
Q: DID WE ADD A TOOTH TO THE REAR SPROCKET?
A: No, we didn’t, but KTM did. In the search for more responsive acceleration and a quicker revving low-to-mid powerband, the 2020 KTM 450SXF has switched from last year’s stock 48-tooth sprocket to a larger 49-tooth cog. This has been a common mod for racers looking to perk up the low-end power and make it easier to use third gear in many of the previous second-gear situations.
Q: WHAT ARE THE MECHANICAL CHANGES TO THE 450SXF ENGINE?
A: From the outside, the 2020 engine looks unchanged from the 2019 engine, but internally there are three important changes.
First, the connecting rod, which is made by Pankl, has replaced its previous coated top-end rod bushing with a true-to-life bronze bushing (it is not brass, as brass is softer and deforms easily). Bronze bushings have replaced needle bearing-style top-end rod bearings in motorsports engines for decades because they are incredibly durable and fail slowly instead of instantaneously like needle bearings. KTM switched to bushings instead of bearings at both ends of the connecting rod several years ago, but the bronze is a step up.
Second, the KTM 450SXF rocker arm’s architecture (topology) has been redesigned to reduce inertia on the intake and exhaust valves. This isn’t just a simple matter of moving material around on the rocker arms but finding maximum rigidity and combining it with minimal weight and decreased polar moments of inertia.
Third, the piston has undergone a series of transformations starting with the box-shaped reinforcement under the piston’s dome and progressing to a CNC-machined and hard-anodized ring groove; however, the most significant piston mod for 2020 was the CP piston’s camming.
Q: WHAT IS CAMMING AND WHY SHOULD I CARE?
A: As you know, the top of the piston, near the crown, has a smaller diameter than the bottom of the piston, near the skirt. Without this tapered profile, the piston would bind in the cylinder bore. If you roll a piston across a table, you will observe that the piston rises and falls in a hump-hump-hump motion that is reminiscent of a camshaft, which is why its shape is called “camming.” The oval shape allows the piston to move freely with the engine’s sidewall thrust forces. The challenge in piston design is to select the proper amount of camming. Too little ovality can cause the piston to contact the cylinder wall close to the end of the piston pin, while too much ovality can cause the piston to push with too great a force against the cylinder wall.
It turns out, in the opinion of KTM’s engineers, their last generation piston was cammed too much. To fix this, the 2020 piston gets a special grind on the skirts to remove 0.01mm of the aluminum’s thickness. That tells us that under extreme temperatures the previous piston was expanding outward and dragging against the cylinder walls via thrust action. Thus, removing a tiny amount of piston skirt width meant the piston didn’t have to endure excessive sidewall thrust. This lessens friction loss and increases piston durability.
Q: AFTER ALL THESE CHANGES, HOW DOES THE 2020 KTM 450SXF RUN?
A: First, let’s recap the six changes to the 2020 KTM 450SXF engine. First, it has a new Map 2 that is crisper and more responsive from low to mid. Second, IG-ACC advances the ignition timing at the opening of the throttle to sharpen the throttle response for a split second. Third, Split Injection’s double burst allows the fuel coming into the combustion chamber to have a cooler combustion-friendly workspace. Fourth, the airbox vents provide more fresh air into the engine than the previous airbox—and internal combustion engines are little more than air pumps that breathe in air and belch out horsepower. Fifth, pooh-pooh it all you want, but adding one tooth to the 450SXF rear sprocket livens up acceleration—not only out of corners, but it brings third gear closer to being the primary gear. Sixth, fixing the camming on the CP piston lessens friction loss to side thrust to the tune of 10,000 times a minute.
The benefits of the six 2020 engine mods are that the power delivery is livelier, quicker and less draggy. We have to give kudos to the KTM R&D department, even if they didn’t give us the map that we wanted. They listened to the American consumer, and their own KTM North American test department, and tried to address the issues that bothered KTM owners.
The chronic power complaints centered around the 2019 KTM 450SXF’s initial throttle response. In short, it accelerated too slowly. Every MXA test rider wished that it were stronger, quicker and more aggressive on the exit of turns. The stock 2019 power was pleasant, but no serious racer wants a 450cc four-stroke motocross powerband that is pleasant. They want power that is assertive, dynamic, bold and brash. A race track is no place for an easy-going, laid-back, gentle power delivery.
That said, we don’t want a fire-breathing dragon of a bike either; we just want to get to the meat of the powerband quicker. We understand that lots of Vets love the metered, controlled and crescendo-style of power that the KTM is famous for, and we don’t want them to lose that. Luckily, they didn’t the 2020 KTM 450SXF power delivery is a mix of steady acceleration, while staying on the torque curve , mated to supreme broadness. A rider who wants less of a rush from low-to mid can easily switch to Map 1, leave the long-turn throttle cam in place and put the rear sprocket back to 48 teeth.
Q: HOW DOES THE 2020 KTM 450SXF HANDLE?
A: We think that KTM’s chassis is the best all-around-handling bike on the track. There are bikes that turn sharper, but they shake more or push more or stand up mid-corner or get loose on corner exit. The KTM chassis requires the least steering input of any 450 made. But, and there is always a but when it comes to handling, in 2019 the frame was made 10 percent stiffer torsionally and slightly stiffer longitudinally. This increase in torsional stiffness, which comes from the redesigned head tube gusseting and a larger cross brace, reduced twisting from the front end during high-load cornering, which paid dividends in overall accuracy; however, that dividend went into the bank account of Pro riders more than slow riders.
The MXA test riders were split on the new stiffer front triangle, with the Pro test riders feeling that the added torsional rigidity made the 450SXF super responsive and the Vets and lightweights vastly preferring the more forgiving feel of the 2018 KTM 450SXF chassis. Pro racers can push the frame and suspension hard enough that the increased stiffness allows them to track straighter, carve harder and use less steering input. As for Vets, they have to set up the forks with plusher clicker settings and lower air pressures to get the 2020 back to where their 2018 was.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Compression clicker. The three-prong compression clicker has been changed to a two-prong clicker. We didn’t think the clicker could get any worse, but two prongs is not better than three. All we really need is longer prongs to make them more accessible to the gloved hand.
(2) Frame stiffness. Making a frame stiffer is a win/lose situation. The stiffer steering head works well for Pros, but Vets think it makes the frame too rigid. If you are on the rigid side of the equation, think about buying a 2020 Husqvarna FC450; it has a much more forgiving setup.
(3) Sprocket/spokes. Watch the sprocket bolts and spokes closely. They loosen up constantly.
(4) Lock-on grips. Although we like the ease of use of the ODI lock-on grips, they deliver a harsher feel to the rider’s hands because the actual rubber is half as thick as glue-on grips.
(5) Frame color. Nobody wants a black frame. KTM needs to paint it orange and leave it orange.
(6) Throttle cam. This is a love/hate category. The stock gray throttle cam has an incredibly long throw, longer than any other bike on the track. It requires many riders to re-grip in order to get full rotation of the throttle. Luckily, KTM includes a black quick-turn throttle cam with each bike. Do yourself a favor and put the black cam in your bike. You don’t have to use all of it, but it’s nice to know you could.
Q: WHAT DID WE LIKE?
A: The like list:
(1) Brembo hydraulic clutch. This clutch is bulletproof. From its CNC-machined basket (with the primary gear machined into the basket) to its Bellville washer (instead of six separate coil springs) to its rubber-suspended cush inner hub to its self-adjusting Brembo hydraulics, no clutch on the track can take the kind of abuse that KTM’s can. This is the dream clutch of every clutch abuser in America.
(2) Electric starting. KTM has had electric starting on the 450SXF since 2007. They know how to do it without adding weight.
(3) Traction control, launch control, two maps. KTM and Husky are the only brands with a push-button, on-demand, traction-control setting (that can be used with either the mellow or aggressive maps). Plus, the same button controls launch control and switches between two maps, which can be done on the fly.
(4) Brembo brakes. The “Big Four” Japanese brands have been throwing 270mm rotors on their old-fashioned master cylinders and calipers to try to keep KTM’s Brembo brakes in sight. They are still behind the curve.
(5) Weight. At 223 pounds, the 2020 KTM 450SXF is 15 pounds lighter than the 2020 CRF450 and YZ450F. You may think that weight doesn’t matter, but a bike’s rims, spokes, frame, shock spring, brake power and acceleration are weight sensitive. There are no factory teams that don’t believe in shedding weight.
(6) Vented airbox. Finally, KTM has responded to its suffocating airbox by giving every buyer the old airbox cover and the new vented cover. Run the vented one.
(7) Slow rev. You hear lots of pundits claiming that the KTM 450SXF does not rev quick enough through the midrange, and that is true. There are 450s that are snappier and more responsive than the KTM in the middle, but they don’t make as much horsepower or torque as the KTM 450SXF does in that part of the curve. KTM designed their powerband to makes its best power dead center in the rev range and they timed out the revs to allow a racer to make the most of the steady, deliberate pull.
Think about it for a second, the KTM’s peak power is at 8800 rpm, while the Honda CRF450’s peak power (59.74) is at 9600 rpm and the Yamaha YZ450 doesn’t peak (58.56) until 9700 rpm. That is very high and very late in the powerband for a 450cc motocross bike. As for the Kawasaki KX450 it peaks at 55.85 horsepower at 9500 rpm—the the KX450’s power output is 2-1/2 horses less than the KTM’s 58.32 horsepower.
(8) TRACTION CONTROL. With the new map, power profile and aribox cover MXA test riders began experimenting with using KTM’s Traction Control button on more dirt surfaces that just hard-pack. For example, on concrete starting line, instead of using Launch Control, they ran Traction Control. It stopped the rear wheel from spinning aggressively off the line. On tracks that were mostly loamy, but had shiny hard spots on the exit of turns, the MXA test riders would run the map they wanted for the loam, but turn Traction Control on. The Traction Control didn’t affect engine power under normal situations, but when the bike exited the hard-pack corners and the rear wheel broke loose, the traction control would kicked in to stop runaway revs. You have to experiement with the settings, but don’t be afraid to mix and match the electronic aids.
Q: WHAT DO WE REALLY THINK?
A: You have to live under a rock not to know that KTM is the target. It is what Honda, Yamaha, Suzuki and Kawasaki are shooting at. We aren’t telling tales out of school when we say that the Big Four have a lot of room for improvement, while KTM has already achieved the top of the mountain when it comes to handling, powerband, brakes, clutch, weight and engine technology.
It is easy for manufacturers who are behind the technological curve to look like they are making progress by simply adding a hydraulic clutch; KTM can’t do that because it is way ahead of the technological curve and has had hydraulic clutches for 13 years. Honda would gain major brownie points by spec’ing a hydraulic clutch, but it wouldn’t add anything to the KTM’s allure because it already has one. American consumers love change, often just for change’s sake, but they aren’t as good at recognizing inherent greatness built on a history of change. The 2020 KTM 450SXF may not look all that changed, but when you look deeper you can see that technological beauty is more than skin deep.
MXA’S 2020 KTM 450SXF SETUP SPECS
This is how we set up our 2020 KTM 450SXF suspension for racing. We offer it as a guide to help you find your own sweet spot.
WP AER FORK SETTINGS
How do the 2020 XACT forks differ from the AER air forks on the 2019 production bike? First, the recommended air pressure is the same 10.5 bar (152 psi) as on the 2019 model but much lower than the 10.5 bar (156 psi) on the 2019-1/2 Factory Edition. This is a dead giveaway that WP is trying to make the forks more forgiving with lighter valving and a lower recommended air pressure. The previous compression valve stack sat on a flat surface, which created suction against the first shim in the stack. On the 2020 Xact fork, the first shim sits on a thin pointy lip, which allows it to open sooner (thanks to less stiction). In essence, this makes the shim stack more responsive to oil pressure. Most successful WP fork tuning focuses on the mid-valve, not the base valve. For hard-core racing, we recommend this fork setup for an average rider on the 2020 KTM 450SXF (stock specs are in parentheses):
Spring rate: 140 psi (Novice), 145 (Intermediate), 152 psi (Expert)
Compression: Compression…20 clicks out (Vet), 15 clicks out (Intermediate), 10 clicks out (Pro)
Rebound: 15 clicks out (18 clicks out)
Fork leg height: Third line
Notes: The recommended air pressure is 152 psi, while the stock compression set is at 12 clicks out and the rebound at 18 clicks out. Most test riders chose air pressure that was lower than the recommended 152 psi (10.5 bar). Once we found the correct air pressure (via the zip-tie method), we used the compression damping to fine tune the travel. The 2020 KTM 450SXF comes with orange rubber rings on each leg to allow the rider to see how much travel he is getting at a given pressure, but orange rings slide down by themselves. We use zip-ties and our best feel was when the zip-tie was within 1-1/2 inches of bottoming. With that pressure, we could use the compression damping to fine tune the travel. Overall, the 2020 AER forks are better than the 2019 production forks.
WP SHOCK SETTINGS
Most MXA test riders liked the overall feel of the WP rear shock, especially after KTM lowered the shock spring rate in 2017 from 48 N/m to 45 N/m. WP did make some technical changes to the 2020 WP Xact shock, but they are mostly focused on a more responsive feel. We run the low-speed compression on 15 clicks out, the high-speed compression 1.5 turns out, the rebound on 10 clicks out (stock is 15 clicks out) and set the sag at 105mm. For hard-core racing, we recommend this shock setup for the 2020 KTM 450SXF (stock specs are in parentheses):
Spring rate: 45 N/m
Hi-compression: 1.5 turns out (2 turns)
Lo-compression: 15 clicks out
Rebound: 10 clicks out (15 clicks out)
Race sag: 105mm
Notes: The WP Xact shock doesn’t feel wallowy, nor does it G-out as much in tough situations. We set the race sag at 105mm (but some riders went as far as 108mm). We started with the high-speed and low-speed compressionon the stock setting but went in on the rebound. All in all, we were rightfully impressed by the shock; however, KTM’s rear shocks are very spring-rate sensitive. The window of the available 42 N/m, 45 N/m and 48 N/m shock springs is very small. The target rider weight of the stock 45 N/m shock spring is 175 pounds. It works well for riders from 160 to 185 pounds, but riders who fall above or below the target range will need to pay close attention to static sag (free sag). It must be between 30mm and 40mm (unladened).