MXA RACE TEST: THE REAL TEST OF THE 2020 HUSQVARNA TX300i

Jun 19, 2023

Q: HOW MANY DIRT BIKES DOES HUSQVARNA MAKE FOR 2020?

A: For the 2020 model year, Husqvarna offers six different full-size bike categories—FC, TC, FE, TE, FX and TX—that account for 13 different machines. The four-stroke motocross bikes are called FCs (and come in FC250, FC350 and FC450 displacements). The two-stroke motocross bikes are called TCs (and come in TC125 and TC250 sizes). The four-stroke enduro/dual-sport models are called FEs (and come in FE350s and FE501s—actually 510.8cc). The two-stroke enduro bikes are called TEs (and come in TE150i, TE250i and TE300i fuel-injected versions). The four-stroke cross-country bikes are called FX models (and come in FX350 and FX450 versions). The two-stroke cross-country bike, and the one that MXA is focusing on, is called the TX300i.

Q: WHAT EXACTLY IS THE HUSQVARNA TX300I?

A: The TX300i is a blend. It is part enduro bike, part motocross bike and part science project. It isn't built for slow-and-go woods riding. It isn't built for motocross racing. It is a six-speed, semi-close-ratio, 300cc, fuel-injected two-stroke. It is designed for fast Western Hare Scrambles, WORCS races, Grands Prix and desert riding. Where does the science project part come in? It is fuel-injected. A fuel-injected two-stroke dirt bike was unthinkable five years ago. Fast forward to the 2020 Husqvarna model lineup, and the only full-size Husqvarna dirt bikes that aren't fuel injected are the TC125 and TC250 motocross two-strokes. Which leads the MXA wrecking crew to the 2020 Husqvarna TX300i (the "i" stands for injected). It isn't a purebred motocross bike, but it is still capable of being raced successfully. How does the TX300i differ from the TC250 motocross bike (there is no TC300i motocross bike)? Here is the list:

(1) Fuel injection. The TC125 and TC250 are fueled by Mikuni TMX carburetors. The TX300i's pre-mix lubrication is fed to the engine via an auto-lube system. The oil is housed in a 700cc oil tank.

(2) Six-speed. The TX300i has a semi-close-ratio six-speed gearbox. The TC250 has a close-ratio five-speed gearbox, while the TE300i enduro bike has a wide-ratio six-speed transmission.

(3) Wheels/tires. The TX300i has an 18-inch D.I.D rear wheel with Dunlop AT-81 off-road tires. The TC250 comes with a 19-inch rear wheel and Dunlop MX3S tires.

(4) Brakes/clutch. The TX300i uses Magura hydraulics for the brakes and clutch, as does the Husky TC250, but its KTM brethren use Brembo hydraulics for brake and clutch actuation.

(5) Fuel tank. The larger TX300i fuel tank holds 2.25 gallons of gas. It is made from translucent plastic so the fuel level can be checked at a glance. The TC250 motocross bike has a smaller 2.0-gallon black plastic fuel tank.

(6) Kickstand. The TX300i comes with a fold-down kickstand. It is removable.

(7) Electric start. Every year motocross racers get lazier and lazier. Many old-school riders badmouthed riders who liked electric starting; now these same riders whine when they get a bike they have to kick. They don't have to kick the TX300i.

Q: HOW DOES THE 2020 TX300i FUEL INJECTION WORK?

A: The Husqvarna TX300i's fuel-injected two-stroke engine is a "transfer port-injected" engine. There is no need to change main jets, needles or pilot jets, because there is no carburetor. What looks like a carburetor is, in fact, a 39mm Dell’Orto throttle body. It does not spritz fuel; its sole purpose is to meter airflow through a butterfly valve and serve as the entry point for the auto-lube oil-injection system.

The Synerject Engine Management System (EMS) has a super-fast processor that depends on sensors to collect data. The sensors are as follows: (1) roll-over sensor (that recognizes when the bike is laid down and shuts off the engine within 10 seconds); (2) crankcase pressure sensor; (3) engine-speed sensor; (4) throttle-position sensor; (5) coolant-temperature sensor; (6) intake air-temperature sensor and (7) new for 2020, an ambient air pressure monitor.

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If the TX300i doesn't get its fuel from the throttle body, where does it come from? There are fuel-injector nozzles, one on each side of the cylinder, that inject fuel into the transfer ports (bypassing the intake tract and crankcase). The EMS uses its data feed to tell the injector nozzle when to spray, how much to spray and how long to spray. Because the fuel is spritzed into the transfer ports at the exact moment that the supplied air is rushing up the transfer ports, the fuel and air are fully misted when the mixture gets to the combustion chamber.

Fuel-injected two-strokes do need pre-mix fuel; they just don't need it mixed in a 5-gallon can. On the TX300i, the gas tank is filled with straight 91-octane or better pump gas. The TX300i's pre-mix oil is located in a 700cc oil tank that is mounted under the gas tank. There is a filler cap behind the steering stem that allows the oil tank to be filled via a flexible tube that runs inside the frame's backbone and into the oil tank. From this tank, the oil is injected at a 70:1 to 100:1 premix ratio. The oil in the tank will last anywhere from four to seven tanks of gas before it needs refilling. If you forget to add oil, an idiot light will come on to warn you. Additionally, you need to run two-stroke oil that is designated for "injector systems." It has a thinner viscosity so that it can be injected more efficiently.

Q: HOW DOES THE 2020 HUSQVARNA TE300i RUN ON THE TRACK?

A: The fuel-injected Husqvarna didn't feel like the previous carbureted Husqvarna two-strokes. It had an electric buzz to the powerband that every test rider mentioned. It didn't have any of the snap, crackle or pop of a carbureted Husky. It just went whirring off in the direction you pointed it. We attribute this to the fact that the Synerject microprocessor can run fuel/oil mixture ratios that are leaner than could ever be achieved by mass-mixing 5 gallons of gas with 16 ounces of pre-mix oil. The computer changes the fuel/oil ratio via feedback from the sensors in milliseconds. It felt a little weird, but it also felt very fast.

We were nervous about the mapping issues that we had last year on our TE300i project bike. Last year's fuel injection had a big dip in the powerband at 7000 rpm that made the engine go "wah, wah, wah." It was very irritating, because it affected the power right where it should have been doing its best work—not its worst. We never found a map to help with the flat spot; however, immediately after the bog, the TX300i was amazingly fast.

Every test rider approached the 2020 TX300i cautiously. They were worried about the bog. Thankfully, it was gone for 2020. There was still a soft spot in the powerband at 7000 rpm but no more "wah, wah, wah." Last year we fixed the bog by installing a special Pro Circuit TE/TX300 exhaust pipe. That pipe not only erased the bog but pumped up the power. As a test, we ordered Pro Circuit's 2020 version of the 300 pipe and shorty muffler. On our 2020 TX300i, it made more horsepower from 6500 rpm all the way to 9000 rpm. It showed a 3-horsepower gain at 7500 rpm and a 3-horsepower gain at 9000 rpm (with more over-rev). This is our go-to 300i exhaust system.

Call us naive, but we expected the TX300i to have a torquey, slower revving, midrange-style of power. After all, it is a big-bore engine. It climbed with alacrity from idle to 7000 rpm, but after that it surprised us by being more of a top-end powerband than a torquer. It was a kick in the pants from 8000 rpm to sign-off (which was at 9300 rpm). Test riders reported that it revved with such gusto through the middle that they thought they had used everything, only to find out that it would keep going. It was at its fastest when revved to the moon—no need to short-shift except for self preservation.

The more we raced the TX300i, the more we grew accustomed to the whiz-bang sounds and eerie way the power felt. It's not that it lacked two-stroke sensations, just that its personality was very one-dimensional. All zing; no character.

Q: DOES IT HAVE PUSH-BUTTON MAPS?

A: Yes. Well, more accurately, it has the old-style KTM two-position map switch that is mounted on the throttle side. You flick it back and forth to change maps (and it puts up a fight before it will move). The two map choices are mellow (two hash marks) and aggressive (one hash mark). This was in the reverse order of previous Husqvarna map switches. We ran it on one hash mark at all times.

Additionally, Husqvarna advised us not to adjust the adjustable power valve. They had suffered some mapping glitches with the ECU on the pre-pro bikes and felt that the fuel-injection maps worked best, as in not too lean or too rich, when the power valve was left on the factory setting. Since the 2020 TX300i was blazing fast where it was, we didn't feel the need to go chasing more power.

Q: HOW WAS THE GEARING?

A: Obviously, the six-speed off-road gear ratios were bound to have some holes where the next gear was too tall to pull as hard as most MXA test riders would have liked. On a motocross track, we forgot about first gear, fifth gear and sixth gear and used the TX300i's six-speed tranny as a three-speed. Off-road, it was about perfect. You could make the TX300i crawl up a steep rocky climb and hit insane speeds across dry lakes.

Q: HOW DID THE 2020 HUSQVARNA TX300I HANDLE?

A: It should be noted that the 2020 TX300i uses the 2020 motocross frame and suspension components, but we struggled in the first few rides with coming to terms with the balance of the TX300i. It was super stable at speed, but it pushed the front end in the corners. Since it felt choppered-out, we started by sliding the forks up in the triple clamps to put more weight on the front wheel. Eventually, when we had three lines showing above the top triple clamp, the TX300i was night-and-day better. Confounding our initial efforts to get the front and rear balanced was the very soft off-road suspension setup. The recommended air pressure in the WP XACT air forks was 9.65 bar (139 psi). When you combined the low air pressure with the softer compression damping, the WP forks bottomed a lot. We decided to put the same settings in the TX300i forks that we used on our TC250 motocross bike—with an understanding that we’d have to make compression and rebound adjustments for motocross use.

One caveat: with the fuel petcock on the left side of the frame (and the left side of the gas tank going farther down than on the right side) we discovered that if you whipped the bike with the left side up, the engine could quit running. Why? The fuel swaps to the other side of the tank (where there is no petcock). Yes, you have to really whip it and be low on gas at the same time, but it happened to us.

Q: WHAT DID WE HATE?

A: The hate list:(1) Height. All motocross bikes are too tall, and the TX300i seems even taller.(2) Maps. It has two maps, but we only used Map 1.(3) 18-inch rear. We like the idea of an 18-inch rear tire and its larger contact patch, but we weren't wild about the off-road-specific 110/100-18 Dunlop Geomax AT81 rear tires or sketchy front.(4) Pre-mix oil. You must run two-stroke oil that is labeled as "oil-injector compatible." Injector oil has a much thinner viscosity to allow it to be pumped through tiny injector nozzles without clogging them.(5) Weight. A Husqvarna TC250 motocross bike weighs 213 pounds. With the addition of the big fuel tank, kickstand, ECU microprocessor, six-speed transmission and heavier off-road tires, the TX300i gained 10 pounds.(6) Price. $10,099.

Q: WHAT DO WE LIKE?

A: The like list:

(1) Engine. The TX300i cranked out 48 horsepower using EFI technology that is only three years old. The best power is found in the upper stratosphere of the rpm range, but there is good power across the board.(2) Brakes. Best in the business.(3) Oil tank. Loved the idiot light.(4) Clutch. The TE300i gets a bulletproof Magura-activated, rubber-damped steel basket and a Belleville washer-equipped clutch.(5) Gas tank. It is pretty awesome that we don't have to premix gas anymore and can see the fuel level at a glance.(6) Chain. As you would expect on an off-road bike, the TX300i gets an O-ring chain or, more accurately, a D.I.D 520 VT2 X-Ring chain.(7) Electric start. Yeah, yeah, yeah. You don't want an electric-start two-stroke, but the TX300i does not come with a kickstarter. You can order one and retrofit it.(8) Fuel injection. Who knew that adding two fuel hoses to the sides of the cylinder was all that was needed to fuel inject a two-stroke?

Q: WHAT DO WE REALLY THINK?

A: We thought that racing a fuel-injected two-stroke would be different from racing a carbureted one. It isn't. It's still "gas and go" just like it always has been; however, the sound and sensations are very unique. One word of warning: If you want a 300cc Husqvarna motocross bike, buy a TC250 and install the aftermarket 300cc kit (which includes the cylinder, head, piston, power valve parts, gaskets and black box). No, it won't be fuel injected, but it will be a great big-bore two-stroke ‘crosser. The TX300i isn't a great motocross bike, and the TC250 isn't a great off-road bike. Pick a side.

This is how we set up our 2020 Husqvarna TX300i for racing. We offer it as a guide to help you find your own sweet spot.

WP XACT FORK SETTINGSOut with the old and in with the new. On the WP XACT AER air forks, job number one is to find the proper air pressure for your weight and speed. After that, do not use air pressure as a tuning tool. That is what the compression and rebound clickers are for. While the stock air pressure is 139 psi, we had riders who went as high as 151 psi. With only one air pressure adjustment, changes can easily be made. Plus, Husky gives you a digital air pump when you buy the bike. These are the settings we ran on the 2020 Husqvarna TX300i (stock settings in parentheses):Air pressure: 145 psi (139 psi)Compression: 12 clicks outRebound: 12 clicks outFork height: 3rd lineNotes: On big hits at pressures below 144 psi, the forks will bottom out (unless you add oil to the fork). Anything above 144 psi and our testers had no issues with bottoming resistance.

WP SHOCK SETTINGSThe WP shock has a good setting. We spent most of our time dialing in the forks, although sag played a big part in balancing out the bike. We were all over the map‚ going as low as 110mm and as high as 100mm. Most test riders split the difference at 105mm, although the sweet spot is between 102mm and 108mm. For hardcore racing, we recommend this shock setup for the 2020 Husqvarna TX300i (stock specs are in parentheses):Spring rate: 42 N/mmHi-compression: 1-1/4 turns out (2 turns)Lo-compression: 8 clicks out (15 out)Rebound: 14 clicks out (15 out)Race sag: 105mmNotes: For riders above 185 pounds or Pros, start first by adding more high-speed compression.

For our 2019 Husqvarna TE300i Project bike build, click here.For our Pro Circuit KTM/Husqvarna 300 TPI Exhaust test, click here.