The 2019 Yamaha YZ450FX received a complete overhaul for this model year. It shares many of the same components as the YZ450F motocross bike, but has several off-road-specific features including a wide-ratio transmission, specifically tuned suspension, a larger-capacity fuel tank, a newly designed composite skid plate, a redesigned aluminum kickstand, an 18-inch rear wheel, a sealed O-ring chain, and special ECU settings designed for off-road riding. The 2019 Yamaha YZ450FX does not come stock with hand guards, but Yamaha installed them on our testbike for the comparison.

2019 Yamaha YZ450FX Engine

Before the shootout got underway, we mounted a Dunlop D404 street tire on the rear wheel and ran the YZ450FX on our in-house Dynojet dynamometer, where it produced 53.24 hp at 9,430 rpm and 32.57 pound-feet of torque at 7,330 rpm. The Yamaha ranks second in the horsepower department and fourth in torque. We then mounted a fresh set of Dunlop AT81 tires to ensure consistency in traction among the four competitors through the duration of the test.

Yamaha YZ450FX in front of colorful mountain.
The YZ450FX was redesigned from the ground up for 2019 with a new engine with wireless tuning capability from a smartphone, an all-new frame, and revised suspension settings to match the new chassis.Jeff Allen

The 2019 YZ450FX has a very strong engine with tractor-like torque. It has great bottom-end, a plentiful midrange, and decent top-end. It does not have the over-rev of its competition, but it pulls low rpm better. This allows you to use a higher gear or a smaller rear sprocket if you want to shift less. The very low first gear came in handy on super-tight and technical trails, and required less clutch work than the three other bikes in the test in such situations.

Yamaha YZ450FX in front of colorful mountain.
Weighing in at 256 pounds, the Yamaha is the second-heaviest bike in the shootout.Jeff Allen

The YZ450FX offers the most tunability with the Power Tuner app and the handlebar-mounted dual map switch. The app works well and makes very noticeable changes to the engine’s performance. It’s a valuable feature, especially on 450s, as the engine’s power delivery can significantly affect the chassis performance. Test riders were able to mellow out the power for low-traction areas and when riding tight single-track. When entering a wider open area of the trail or the motocross track, they were able to return to the standard map with the push of a button.

Yamaha YZ450FX Dyno chart.
The YZ450FX produces 53.24 hp at 9,430 rpm and 32.57 pound-feet of torque at 7,330 rpm.Jeff Allen

The clutch is very consistent with a smooth pull and almost no fade. The engine shifts smoothly with minimal clutch input. The Yamaha YZ450FX has slightly more engine-braking than the other three bikes in the test. The airbox noise is noticeable at first, but becomes normal after a few minutes of riding. The muffler is not as loud as the Honda's, but not as quiet as the Husqvarna's or KTM's either.

Yamaha YZ450FX riding on dirt track.
The Yamaha has a very strong engine with tractor-like torque and a wide-ratio transmission.Jeff Allen

2019 Yamaha YZ450FX Suspension

Yamaha’s KYB Speed Sensitive System (SSS) fork and KYB shock are easily the best stock suspension components. They are remarkably plush and confidence inspiring. The adjusters have a good range for stiffening or softening, and the spring rates feel very balanced. The stock settings are a touch soft for faster, heavier load situations, but are very close to being perfect for slower to medium-speed single-track. Stiffening compression on the fork and shock resulted in a little more hold-up on bigger impacts, high-speed rollers, jump takeoffs, and landings. This additional hold-up even helped in the smaller bumps by keeping the suspension up higher in the stroke. The Yamaha’s suspension had the best overall performance on the trails and the motocross track.

Yamaha YZ450FX riding through rocky terrain.
The YZ450FX offers the most tunability with the Power Tuner app and the handlebar-mounted dual map switch. The app works well and makes very noticeable changes to the engine’s performance.Jeff Allen

2019 Yamaha YZ450FX Chassis/Handling

The 2019 Yamaha YZ450FX weighed in at 256 pounds on our automotive scales, which makes it the second-heaviest bike in the class. It’s very stable and is the most planted feeling bike in the shootout. It’s not the nimblest handling machine and feels a touch heavier than its competition as well. It doesn’t turn as sharply or easily as the 2019 Honda CRF450RX or the two Austrian machines, but it corners well, especially for a bike that leans more toward stability.

The Yamaha YZ450FX’s ergonomics are improved for 2019. The radiator shrouds are noticeably thinner than the previous model, but are still a touch wide in comparison to the KTM and Husqvarna. Yamaha did an excellent job with the larger gas tank. It’s 100 percent hidden, isn’t noticeable when riding, and has little to no effect on the chassis from full to empty. The YZ450FX feels balanced with 105mm of shock sag. Some test riders preferred to run less sag—between 100mm and 102mm—to put more weight on the front end and help cornering.

The rider position is a bit off, which mostly has to do with the seat. It has a noticeable dip that is a little too far back, preventing the rider from getting far forward enough to achieve maximum cornering performance. A taller seat would not only make it easier to stay forward when sitting, it would also require less effort to go from sitting to standing and create less of a sit-in feeling. The handlebar also feels high in relation to the seat. A taller seat would help this sensation as well, but lower bar mounts would suffice too. Also, we like that the 2019 YZ450FX is equipped with a skid plate but would also prefer to see it come with hand guards in stock trim as well.

Yamaha YZ450FX jumping.
Yamaha’s KYB Speed Sensitive System (SSS) fork and KYB shock are easily the best stock suspension components.Jeff Allen

Why It Won

The YZ450FX is the best overall 450 off-road bike for everything from low- to high-speed off-road riding. It works great on the motocross track too. It has a strong engine with tons of torque, the best suspension, the most stability, the plushest ride, and state-of-the-art tunability.

Why It Shouldn’t Have Won

It’s somewhat heavy feeling and not as nimble as the other bikes in the shootout. The seat-to-handlebar height is a bit off too.

Yamaha YZ450FX riding off-road.
The YZ450FX is the most planted feeling bike in the shootout. It corners well, especially for a bike that leans more toward stability.Jeff Allen