MXA RACE TEST: THE REAL TEST OF THE 2019 HUSQVARNA FC450

Q: FIRST AND FOREMOST, IS THE 2019 HUSQVARNA FC450 BETTER THAN THE 2018 FC450?

A: Yes. This is the bike that won the 2018 AMA Supercross Championship with Jason Anderson. With its SOHC (single-overhead-camshaft) engine, new bodywork, more compact cylinder head and new exhaust system, the FC450 delivers usable, but not spectacular, power for everyone from Pro to Vet.

Q: WHAT’S NEW ON THE 2019 HUSQVARNA FC450?

A: Pretty much everything. The engine, frame, cylinder head, swingarm, subframe, fuel pump, transmission, cooling system, triple clamps, exhaust system, maps and intake tract are all new.

Q: HOW DOES THE 2019 HUSQVARNA FC450 DIFFER FROM THE 2018 HUSQVARNA FC450?

A: There are a lot of differences between the 2019 and 2018 bikes. They aren’t all whiz-bang, high-profile, buzz-worthy mods, but they are based on solid technology. Here is a quick—but by no means complete—list of mods.

(1) Torsional rigidity. The 2019 frame is 10 percent stiffer torsionally and 2 percent stiffer longitudinally.

(2) Cylinder head. Husqvarna’s 2019 cylinder head is 15mm lower than it was in 2018.

(3) Pankl transmission. The 2019 FC450 comes with complete Pankl gear sets.

(4) Exhaust. The 2019 Husqvarna FC450 exhaust is all new, but, most significant, Husqvarna added a slip-fit in the mid-pipe to allow the pipe to be removed without having to take the shock off the bike.

(5) Ergos. The 2019 plastic has been adopted from the 2018-1/2 Husqvarna FC450 Rockstar Edition.

Q: WHAT DO THE 2019 MODIFICATIONS REALLY DO?

A: Most new bike buyers are hot-to-trot. They have money burning a hole in their pockets, and they want to trade it for a new machine. They don’t really read the updates carefully enough to comprehend what the manufacturers did or didn’t do. They just know that they gotta have it. MXA wants to dig deeper into the 2019 Husqvarna FC450 updates for more of the whys and wherefores.

Q: WHY WOULD HUSQVARNA LOWER THE CYLINDER HEAD?

A: Husqvarna’s compact SOHC cylinder head is 15mm lower and 1 pound lighter. Thanks to the lower design, the camshaft is closer to the center of gravity, significantly reducing the gyroscopic effects of rotational inertia. By lowering the camshafts, Husky’s engineers were able to incorporate shorter and stouter cam towers to resist torsional vibration and twisting forces that can make cams jump around in their bosses. The lower cam position allows the valve stems to be shorter, which reduces leverage in the skinny stems. With a refined cam surface grind, DLC rocker arm and a low-friction cam chain guide, you get a valve train with less weight, decreased rotational inertia, stronger cam towers, shorter valve stems and a 1-pound weight reduction. Not only is the gyroscopic effect of the rotating mass lessened on the chassis, but cam vibration and positional error are reduced.

Although only the FC450 gets the new cylinder head for 2019, the greatest benefit of a dynamically stronger valve train will come when applied to the much-higher-revving FC350 and FC250 heads where 14,000 is easily obtained. Thus, when reading new bike specs, don’t gloss over concepts that are more significant than “anodized,” “coated” and “polished.”

Q: WHAT’S THE BIG DEAL WITH TORSIONAL AND LONGITUDINAL RIGIDITY?

A: Torsional rigidity is the minimum force required to deform an object by twisting it. If that object is a motorcycle frame, you will find the most torsional flex in the steering head, swingarm pivot and swingarm. Longitudinal stiffness is best characterized by the stiffness of a beam. If that beam represents the backbone of a motorcycle frame, you will find the most longitudinal flex when landing from jumps. In essence, longitudinal forces try to stretch the motorcycle’s frame, while torsional forces try to twist it like a pretzel.

It would be easy to build a motorcycle frame that was stiff both torsionally and longitudinally, but history has proven that a frame that is too stiff is problematic. If you owned a 1997 Honda CR250, you have first-hand experience with this concept. The CR250 was too rigid. It delivered a harsh ride and forced the suspension to do the work of absorbing stress loads. And, of course, history is full of spaghetti frames that handled so poorly that they had a hinge in the middle.

A motorcycle frame must have the proper modulus of rigidity (known as “shear modulus”). It must deform just enough along its axis to not break but not be so stiff that it is unforgiving. Husqvarna’s and KTM’s chromoly steel frames are more forgiving than the cast, extruded and forged-aluminum twin-spar frames of the “Big Four.” The challenge for a frame designer is to keep the absorbent longitudinal rigidity while increasing torsional rigidity. This is tricky, because stiffening the head tube almost always stiffens up the backbone. Somehow Husqvarna found a way to make the 2019 frame 10 percent stiffer torsionally and only 2 percent stiffer longitudinally.

Most test riders can feel the increased torsional rigidity at turn-in. The frame is much more responsive to steering inputs because the twisting loads on the steering action are held in check.

Q: WHAT IS A PANKL RACING SYSTEMS GEARBOX?

A: Pankl Racing Systems is an Austrian-based, high-performance drivetrain company that produces parts for Formula 1 teams. For 2019 the FC450 will be using complete Pankl gearboxes in its four-stroke models. The forged steel parts go through multiple stages of machining, heat treatment and stress relief. Pankl uses the purest steel available with less sulfur content than normal gears  The Husqvarna’s Pankl transmission features the exact same gear combinations and ratios as the 2018 gearbox, but the Pankl gearbox in the FC450 engine is on a metallurgical par with a factory team’s custom works transmissions.

Q: WHAT’S NEW WITH THE ELECTRONICS SUITE?

A: The push-button ECU maps have been changed on the FC450s. The stock map (#1) is slightly mellower, while the aggressive map (#2) is slightly more aggressive. The goal was to have a bigger difference between the two maps. Designed for easy operation, the standard map switch on the FC450 activates launch control, traction control and the two ECU maps.

For launch control, the rider has to push the traction control (TC) and the map button simultaneously for two seconds. When launch control is engaged, the light behind the front number plate will flash continuously. Launch control knocks off several horsepower from 7000 rpm on up. This reduced horsepower lessens wheelspin, helping the bike get off the line straight. It shuts itself off as soon as the throttle is closed by more than 30 percent going into the first turn.

Traction control can be turned on or off by pressing the TC button on the multi-switch. The TC function analyzes throttle input, throttle position and the rate at which engine rpm increases. If the ECU recognizes runaway revs, which registers as wheelspin, the ECU retards the ignition to lessen power to the rear wheel to regain traction. Most MXA test riders only use traction control on muddy days and find it annoying on tracks with even a modicum of traction.

Working in conjunction with the new mapping is something called IG-ACC. It 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 (and does not work any other time). By advancing the ignition every time you turn the throttle from closed to open, you get an added boost of juice.

Do you remember when Honda tried something called “Dual-Timing” injection back in 2014. Honda dropped the idea, but Husky thought it had merit and worked hard to refine the ECU mapping. For 2019 the FC450 gets “Split Injection.” Think of Split Injection as one long burst of fuel through the injector port that is broken into two halves. The first short-duration spray cools the back of the intake valves, so the long duration spritz has a denser air/fuel mixture to work in. This results in more usable power across the midrange.

Q: WHAT’S UP WITH THE FC450 EXHAUST SYSTEM?

A: The FC450’s exhaust is shorter with a larger resonance chamber and shorter muffler, but, most significant, Husqvarna added a slip-fit in the mid-pipe to allow the pipe to be removed without having to take the shock off the bike. The FC450 is very quiet. It registered 93.2 dB on the 94-dB Amateur sound test and 111.4 dB on the AMA/FIM Pro-level 114-dB two-meter-max test.

It should be noted, as we will see in the dyno runs, that the FC450 muffler is good at sound testing because it has a restrictor-style perf-core cone stuck in the muffler. This metal ice cream cone kills throttle response at low rpm and contributes to the 2019 Husky FC450 being 1 horsepower down to the unrestricted 2019 KTM 450SXF muffler.

Q: IF THE MUFFLER HURTS THE POWER, WHAT ELSE DOES?

A: MXA is suspicious that the Husqvarna engineers are clueless about airflow through the intake or airflow out the muffler. The 2019 Husqvarna FC450 is choked down on both ends of the system. One look at the tight confines of the 2019 Husqvarna airbox explains why the Husky feels like it has a rag in the airbox. In truth, it doesn’t have a rag in the airbox, but it also doesn’t have any air in the airbox.

To prove the point, the MXA wrecking crew ran the 2019 Husky FC450 on the dyno and on the track with the airbox cover off. On the dyno, we gained one horsepower from 10,000 rpm to peak, which was 56.40 with the stock airbox and 57.50 with more air flowing in. On the track, every test rider was impressed with the snappier throttle response and quicker pick-up of the opened-up airbox—and when we combined that with the straight-through muffler from a KTM 450SXF, it was like a different bike.

The solution? Take a Makita drill motor and a 1-inch hole saw bit and start drilling. The Rockstar Husqvarna factory team told us to make all of the holes behind the air filter—not next to it—and that we could drill into the part of the plastic subframe that leads to the hollow section of airbox space. Measure twice, drill once.

Q: HOW DOES THE 2019 HUSQVARNA FC450 RUN?

A: We hated giving up free horsepower. After all, this is a racing motorcycle, but it doesn’t feel like one. It doesn’t have any hit, burst, blast or bark. Surprisingly, most MXA test riders liked the mellow power delivery. Yes, they noticed it, but they always mentioned that they didn’t want to complain about an engine that still made enough peak horsepower to stay within one horsepower (above or below) of the 2019 KX450, 2019 KTM 450SXF and 2019 Yamaha YZ450F.

Every test rider thought that the Husky delivered something that no other bike offers in 2019—a powerband that is so usable that it feels like a rheostat. You just dial the power in and the lights get brighter, or dial it down for a little mood lighting. It is amazing how easy it is to go fast when the bike you are riding doesn’t feel like it is going fast.

There is no doubt that this is a Vet-style powerband, with the caveat that you can turn up the lights with a slip-on muffler and a drill bit. The 2019 Husqvarna FC450 makes 56.40 horsepower, and it makes it across an incredibly wide range that almost makes the FC450 a two-speed on most tracks. Not that you can’t use first, fourth or fifth gears, but why confuse life with more shifting than necessary.

Q: WHAT DID WE HATE?

A: The hate list:

(1) Spokes. Good news! Husqvarna redesigned its spoke nipples for 2019. Bad news! They still come loose.

(2) Blue frame. The blue frame paint that Husky chose is ugly. Plus, they covered it up with black frame guards.

(3) Husqvarnitis. What is Husqvarnitis? It is the motorcycle equivalent of emphysema. The cure? Take an aspirin and a hole saw bit and call us in the morning.

(4) Graphics. What graphics?

(5) Hydraulic clutch. Husqvarna and KTM have the same incredible diaphragm clutch, but KTM uses a Brembo hydraulic system and Husky uses a Magura setup. The Magura clutch slave unit on the FC450 (not the FC250 or FC350), has suffered lots of seal failures. We thought Magura would fix the problem for 2019, but they didn’t. Be prepared to install a KTM piston and seal in your FC450 when the clutch goes out.

(6) Subframe. Husqvarna exchanged last year’s three-piece plastic subframe for a new two-piece design. It is stronger and lighter, but most MXA test riders preferred the feel of the old three-piece design. It made the chassis feel more supple.

Q: WHAT DID WE LIKE?

A: The like list:

(1) Weight. The Husqvarna FC450 gained a pound for 2019 thanks to the beefier top triple clamp, 5mm-longer swingarm and ice-cream-cone muffler; however, at 224 pounds, it is the second-lightest 450 on the track (and 9 pounds lighter than the third lightest bike).

(2) Brakes. Great brakes. The best brakes.

(3) Air filter. The Twin Air air filter comes with a foolproof mounting system.

(4) Skid plate. Husky welded mounting tabs under the frame to hold a skid plate. Nice touch.

(5) Hydraulic clutch. Slave-unit seal problems aside, the Husqvarna clutch makes Japanese clutches look like they came off of a Soap Box Derby car (even the 2019 Kawasaki KX450 hydraulic clutch). With its integrated steel basket/primary gear, Belleville washer in the place of the coil springs and a clean design, you can expect double or triple the life from Husky clutch plates compared to the “Big Four.” If you are a clutch abuser, this is the only clutch you should abuse.

(6) Radiators. The radiators are mounted 12mm lower on the frame, and the water capacity is up 20 percent.

(7) Handlebars. ProTaper handlebar with new bend.

(8) T-piece radiator hose. Husqvarna uses 4mm-larger hoses to channel water through the central tube that runs through the frame. The new tube increases water flow through the gore points of the T-piece inside the head for a more consistent coolant flow.

Q: WHAT DO WE REALLY THINK?   

A: The 2019 Husqvarna FC450 has more responsive midrange power (helped by Split Injection); snappier and quicker initial throttle response (thanks to IG-ACC); reduced rotational mass (courtesy of the redesigned cylinder head); thinner, flatter and narrower ergonomics; an exotic Pankl gearbox; more accurate steering response at turn-in; better chassis control in off-throttle situations; and every electronic aid known to man. All of this in a package that comes in at 224 pounds.

We are, however, confused as to why Husqvarna’s engineers would build a motocross bike with a restrictive muffler and airbox, especially since these two issues are easily resolved (even by the consumer). More confounding is why Husky didn’t demand that Magura fix the obviously flawed clutch-slave unit seal, leaving it to the consumer to replace it with a competitor’s part when it fails (and it does fail). The MXA wrecking crew has pointed out these flaws for the past several years, so we know that Husky is aware of them. It pains us to know that with the addition of more airbox vents, a straight-through muffler and a better slave seal, we would be praising the 2019 Husqvarna FC450 to the moon. Love the bike; wonder about the management.

MXA’S 2019 HUSKY FC450 SETUP SPECS

This is how we set up our 2019 Husqvarna FC450 for racing. We offer it as a guide to help you find your own sweet spot.

AER FORK SETTINGS
We are willing to bet that Husqvarna has the oldest demographic of any motocross bike sold in America. Its largest following is in the Vet, Over-40 and Over-50 classes. These older riders are “their people”—old enough to remember the glory days of Husky, rich enough to pay the premium price and willing to avoid the KTM stampede. That means that Husqvarna should make its fork setup considerably softer than the current base settings. Yes, we know that there are fast riders on Husky FC450s, but very few fast guys run stock suspension—regardless of the brand they race. That said, we recommend that most Vet, Novice and slow riders run lower air pressures than the OEM recommended settings—in the 130-psi to 145-psi range. Additionally, any rider who feels that the WP forks are too harsh at the end of the stroke should lower the oil height in the damping leg by 10cc (we have gone as far as 20cc). This will smooth out that midrange spike. For hardcore racing, we recommend this fork setup for an average rider on the 2019 Husqvarna FC450 (stock specs are in parentheses):

Spring rate: 145 psi (152 psi)
Compression: 25 clicks out (15 clicks out)
Rebound: 17 clicks out (15 clicks out)
Fork-leg height: Third line
Notes: Additionally, pay attention to extreme temperature changes, especially from morning practice to the second moto. It doesn’t hurt to reset the air pressure to your chosen settings between motos (once the forks have cooled down from riding). Always bleed the outer chambers at regular intervals.

WP SHOCK SETTINGS
The WP shock features a pressure-balanced design to keep internal pressures consistent. There is progressively stiffer compression damping at low speed, mid speed and high speed. Balancing the pressure inside the shock makes the damping more consistent; you can achieve with one click what would have taken two or three clicks on last year’s shock. The stock 45 N/m is well-suited to the target audience, but if you are lighter than 150 pounds, consider switching to the 42 N/m spring from the FC250/350. If you are heavier than 185 pounds, you might want to run the 2016 Husqvarna FC450’s 48 N/m spring. MXA test riders don’t stray far from the stock 15 clicks out on compression, but we make necessary changes to the high-speed dial. For hardcore racing, we recommend this shock setup for the 2019 Husqvarna FC450 (stock specs are in parentheses):

Spring rate: 45 N/m (42 N/m under 150 pounds). 48 N/m over 185 pounds)
Race sag: 105mm
Hi-compression: 1-3/4 turns out (2 turns out)
Lo-compression: 15 clicks out
Rebound: 10 clicks out (15 clicks out)
Notes: We turned the high-speed compression damping in 1/4 turn to lessen G-outs and run more rebound than the recommended setting. Additionally, we set the sag at 105mm instead of the WP-recommended 110mm.