First Impression: 2021 Yamaha YZ450FX

All New XC Racer In Blue

Story by Trevor Hunter

The bLU cRU has been on an upward trend as of late with their 450cc motorcycles, both on the moto track and in the off-road arena. The Star Racing Yamaha effort has found success in Supercross and now finishing 1-3 at the first AMA Pro Motocross of the year, and the AmPro Yamaha Team has been a race winning threat all year in East Coast Off-Road. As of 2021, they are starting again sharing the same basic platform, with the ‘21 YZ450FX now receiving the updates that the YZ450F received in 2020. 

Changes: Although the cases are the same, nearly all of its guts have been revised. The most noticeable is the new head design, which is claimed to make a difference in both the power output and the handling since it is lower and more compact. The cams and port shapes have all been changed drastically, as well as a newer high-compression piston (12.8 to 13.0:1). Down below, the connection rod is 1.5mm longer to reduce side loads during the piston stroke. The ECU also offers a two-way programmable map switch via the handlebar and can be switched on the fly while riding, no need to stop. 

The chassis geometry and pickup points remain the same but the frame thicknesses have been altered in key areas. The top mount has gone from aluminum to steel and the lower, steel to aluminum. To further alter the feel of the chassis, Yamaha put more flex into the top triple clamp and also reduced the front axle inner diameter by 1.4mm or 20% less rigidity. As a result of the chassis changes, Yamaha addressed the suspension settings to compliment each other. Braking has been a hot topic over the last few years and Yamaha’s possible answer is a new caliper with larger pistons and more surface area on the brake pads and front rotor. In the rear, the caliper hanger is lighter by a quarter pound and disk size has been reduced by 5mm to just 240mm. The front handlebar position has been lowered by 5mm and the bar mount position now comes standard in the forward position (pre-2021 in the rear position). The bar mount can still be adjusted four ways, up to 26.5mm rearward and 10mm forward if needed. Tires have been updated to the Dunlop MX33 from MX3S, not AT81s like most other off-road bikes come with. For more in-depth info on the changes, check out our 2020 YZ450F article HERE.

Power: Yamaha continues to deliver in the power department as they have returned with a wicked fast 450cc four-stroke powerplant. The YZFX has a very broad powerband starting with a meaty bottom end and steadily lays down power as you climb the RPM’s with no big surges or drop offs. There’s enough meat to ride a taller gear through corners and short shift the bike, which also allows the chassis to settle and remain smooth in choppy sections. Or, you can get aggressive and rev the bike out and still get from point A to point B in a hurry. In general, the bike has more power and is much more aggressive in nature compared to the older version.

The initial crack of the throttle is very responsive, at times too much, but it then transitions into smoother power as the RPMs build. It is a little jerky and unsettling, even when rolling a taller gear, and our lighter testers not used to 450 power found it making the bike difficult to ride at first. The solution to this was to change up the mapping. We tried a couple of different maps, including the “Hard Pack” map that comes as a preset with the GYTR Tuner App and the handlebar map switch. This tamed down that initial hit, but we were also feeling the effects as the RPMs increased which wasn’t exactly what we were looking for. We’ve also tried running the “Magic Map” which we enjoyed on our YZ450F mx test ride later last year, and that map was also welcomed for an easier-to-ride character that retained some excitement when wanted. We’re going to continue working on some maps as we ride the bike more as it really plays a big part in the power delivery and also how the chassis feels and reacts. 

The transmission is the same 5-speed, wide-ratio tranny as the WR450F. The gaps weren’t all that noticeable, especially in the open desert, and it is one of the best 5-speed WR transmissions that we’ve tested. A 6-speed transmission would be welcomed but this one gets the job done. We reached 75MPH rather easily, but still had plenty more left in the tank if the terrain had allowed for it. Likewise, 1st gear is very low, almost unusable anywhere except in extremely tight terrain. The clutch pull is pretty smooth, stiffer than the 250’s but still easy to pull. 

Suspension: The coil-spring KYB components are a standout feature on YZFX again in 2021. Yamaha has all but mastered blending small bump absorption with excellent bottoming. In our quick time on the bike thus far, we’ve traversed from rocky single track to deep sand whoops without having the need to touch a clicker. Even with lighter weights on the bike, we didn’t experience much deflection or harshness in the slow stuff, but had enough bottoming to withstand a deep sand track.The stiffer in nature suspension pairs well with the updated chassis in that it is more reactive to rider movements and less wallowy than previous versions. 

Handling: Moving on to the handling, the 450FX isn’t entirely the “Cadillac” that it once was. Like the YZ450F MXer, the 450FX is more precise and nimble with a more aggressive and lively feel. There is still stability and comfort in the chassis, just a tad less of it as it brings in more precision like a Ferrari. Late in the day at Glen Helen when the track was edgy and dry, we were lacking some comfort in the bike and found the front end to be a little nervous feeling. For 2021, the handlebar mounts come in the forward position as opposed to the back position, and with our smaller in stature riders on board, changing it to the back mount helped quite a bit. It settled the bike down and put us in a more neutral and comfortable position on the bike which helped a lot. We’ll continue to play with this as we continue to log laps and miles in on the XC racer.

Yamaha heavily updated the 2021 YZ450FX and we’re impressed after our first rides. The power is plentiful, yet tuneable with the GYTR App and you can dial it up or down to your liking in a matter of seconds. The suspension feels as good as ever, transitioning well over a variety of terrains seamlessly. The handling is precise yet still comforting, and the scale weight certainly doesn’t translate out on the trail. It is one of the lighter feeling bikes and it maneuverable similar to some of the lightest bikes on the market.

We’ll continue to put hours on the bike to dive deeper into the nuances that make up the latest generation YZ450FX.

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