2018 Yamaha YZ250FX Review: Off-Road Magic

December 30, 2018

2018 Yamaha YZ250FX Review: Trail Tested

Yes, we know the 2018 Yamaha YZ250FX is designed to be an off-road racing motorcycle intended for AMA Hare Scrambles and GNCC competition.

Last time we tested the YZ250FX, we raced it and found it to be an impressive mount after some light modifications. This time, the YZ250FX gets put to the test as a trail bike for the rider who demands serious performance, even when riding for pleasure.

Although it is a race-ready motorcycle, the 2018 Yamaha YZ250FX is fully usable at less than race pace. The motor, while derived from the YZ250F motocrosser, has an off-road powerband that is more easily controlled. A wide-ratio six-speed transmission adds to the off-road flexibility of the motor.

The YZ250FX’s KYB suspension is tuned for the lower speeds and the kind of obstacles you will find on a challenging trail. The linkage rear suspension and speed-sensitive fork damping give the YZ250FX the multiple personalities needed to work as an off-road racing motorcycle, as well as a serious trail bike.

Yamaha thought outside the box with the YZ250FX’s motor. The top-end is canted slightly rearward for improved mass centralization, and the air intake is in the front of the cylinder. With the exhaust gasses exiting to the rear, the header pipe wraps around the cylinder for the needed length for proper exhaust tuning, before the fumes exit from the right side of the motorcycle.

The motor design also allows for the airbox to be placed in the location traditionally assigned to the fuel tank. The two-gallon fuel tank sits, primarily, under the front of the seat. Again, this is part of a successful effort to centralize mass for improved handling.

It’s difficult to say which is better—the chassis or the motor. They work in concert, which is why the 2018 Yamaha YZ250FX is such a potent off-road racer, as well as a stunning trail bike. Regardless, let’s start with the motor.

We tested it with a GYTR by FMF Aluminum PowerCore 4 Hex muffler ($350), with a USFS-approved spark arrestor to keep it legal in California public riding areas.

The motor is truly a stroke of genius. The YZ250FX has a usable powerband from 4000 to 13,000 rpm or so. It runs cleanly from idle, making it possible to find traction in the ugliest of conditions. The Dunlop Geomax MX3S tires are state-of-the-art, and do their part in soil conditions that range from sand to cement-like hardpack.

With that in mind, the YZ250FX is also willing to have its neck wrung when conditions are right. In the sand, it is great to be able to have plenty of overrev to keep the wheel spinning and the bike moving forward in an easily controllable manner. More traction means more speed, and running the YZ250FX powerplant wide open is pure joy. A 450 is intimidating for me, while the 250 gives me the feeling of total control.

On tighter trails, the broad powerband means fewer shifts. I can let the motor keep revving instead of shifting up and then down again when entering the next corner. Torque peaks around 8500 rpm, so there is always pull on tap.

Braking is exemplary, with the sweet combination of great feel and absolute power. Associate Editor Jess McKinley, who rides at a much harder level than I do and is the photo rider, has cooked the rear brake fluid. That hasn’t been a problem for me, however.

I particularly like the way the YZ250FX motor allows me to manipulate the placement of the front wheel. On technical trails strewn with debris, I can intuitively lift and place the front wheel as needed.

While I don’t skip whoops, I can jump them, and the snap of the short-stroke motor makes it possible. This is a huge confidence builder, as I always have the 2018 Yamaha YZ250FX where I want it. When that’s happening, I can ride faster and safer.

Yamaha’s accessory GYTR Power Tuner works on the 2018 Yamaha YZ250FX. Because I do a wide variety of riding, I’m happy to leave the mixture and tuning maps as-is. However, if I rode tight single-track exclusively, I’d try tamping down the top of the rev range. There’s no nasty bark off the bottom that needs to be tuned out, so that would be untouched for me.

The clutch has proven bulletproof. I don’t have to slip it constantly to keep the revs up, so it gets relatively light use in all but the toughest terrain. I’ve yet to miss a shift when using the perfectly spaced six-speed transmission.

The chassis of the YZ250FX perfectly complements the motor. It takes the input of the rider and engine, and turns it into poetry in motion. Cornering can be easily accomplished motocross-style, up on the tank to plant the front wheel, or in a traditional off-road style where the body position is more neutral and steering is done with the rear wheel. It’s great to have that choice, and the YZ250FX accommodates either preference.

Considering the 2018 Yamaha YZ250FX lacks a stock steering damper, it is remarkably stable at speed in rough conditions. Again, part of this is due to it only putting 250cc of power to the ground, rather than having to struggle against 450cc. Still, the YZ250FX feels great when tapped out in sixth gear, even when the going gets unpredictably rough. That is a huge advantage in racing, and it carries over to fast trail riding.

The KYB suspension works at a wide range of speeds and commitments. This means less fatigue, so you can drain the two-gallon tank without getting arm-pump. The Speed-Sensitive System KYB fork is fully adjustable, though the stock settings are entirely satisfactory for my weight and speed. When I was taking it easy, the fork was plush. As I ramped things up, the KYB fork followed suit transparently.

The KYB shock is set up to match the action of the fork. There is never a moment of seesawing or unexpected unequal reaction to the suspension. Again, this is a massive boost to confidence. I never felt like the suspension was working against me. Instead, it is my best friend, aiding and abetting me when things get fast and furious, as well as bailing me out before I get into too much trouble due to poor decisions.

Ergonomics are spot-on for me, and the 2018 Yamaha YZ250FX feels perfectly natural to ride. I can move around on the seat quickly, and nothing gets in the way. The bars are rubber-mounted, which is nice, along with the vibration damping tapered aluminum bars. Yamaha gives you four positions to mount the bars, should your size or preference be outside of typical.

Large 55mm footpegs provide an excellent platform for your boots. All controls—clutch, brakes, and shifter—are where you expect them and react as intended.

The 2018 Yamaha YZ250FX has e-start, of course, and that makes a huge difference in rugged terrain when stalls can occur. Routine maintenance—oil changes, air filter cleaning (no tools required), and chain adjustment—are all simple. Because of the positioning of the air intake up high and forward, the air filter stayed impressively clean. We’re huge fans of the incredibly durable embedded graphics.

Functionally, the 2018 Yamaha YZ250FX is virtually perfect, but there are upgrades you might want to make. We would like to see handguards stock on the YZ250FX. Conveniently, Yamaha does sell Cycra Factory BroBend CRM Racer guards ($170/pair).

You may or may not be satisfied with the expansive stock plastic skidplate. Those in high-speed rocky terrain, such as the desert, will want to spring for something made from aluminum. A GYTR rear disc guard ($113) isn’t a bad idea, either.

For the radiator, it’s worth considering the crash protection of GYTR radiator cages ($134) and the hot-weather safety net of a radiator fan kit ($73). If you can’t stand the idea of no backup kickstart, Yamaha has a $211 kit that will hook you up.

To say that I love riding the 2018 Yamaha YZ250FX is an understatement. As of model year 2018, it is my favorite off-road motorcycle of all-time. It’s incredibly easy to ride fast, and also willing to effortlessly accommodate me when I’m in a less aggressive mood, or just tired. The motor and the chassis seem to be purpose-built for me, so when I’m riding, I feel like I am a class higher than normal.

Photography by Don Williams

Riding Style

Helmet: Shoei VFX-Evo
Goggles: Ariete RC Plus
Jersey + pants: Fly Racing Lite Hydrogen
Gloves: Fly Racing Lite
Body armor: Alpinestars Sequence Protection
Boots: Gaerne SG-12

2018 Yamaha YZ250FX Specs

ENGINE

Type: 4-stroke single
Displacement: 250cc
Bore x stroke: 77.0 x 53.6mm
Compression ratio: 13.5:1
Valvetrain: DOHC w/ four titanium valves
Fuel delivery: Keihin EFI w/ 44mm throttle body
Transmission: Wide-ratio 6-speed
Clutch: Wet multiplate
Final drive: Chain

CHASSIS

Front suspension; travel: Fully adjustable inverted KYB Speed-Sensitive System fork; 12.2 inches
Rear suspension; travel: Linkage-assisted fully adjustable KYB shock; 12.5 inches
Tires: Dunlop Geomax MX3S
Front tire: 90/90 x 21
Rear tire: 110/100 x 18
Front brake: 270mm disc w/ Nissin caliper
Rear brake: 245mm disc w/ Nissin caliper

DIMENSIONS and CAPACITIES