2021 YAMAHA YZ450F: FULL TEST

If ever there was proof that pro-racing results don’t matter in the real world, the Yamaha YZ450F is it. It continues to be one of the best-selling motocross bikes in America. It continues to be wildly successful in the hands of local riders. It continues to be reliable, accessible and effective in the hands of grass-roots, amateur racers. In pro racing, on the other hand, the YZ450F has been almost invisible in recent years. We could speculate about the reasons endlessly without coming to any solid conclusion, but we know this: it’s not about the production bike. The current YZ450F is one of the all-time greats.

MECHANICAL MASH UP
The Yamaha YZ450F has always been an off-beat motorcycle, unaffected by fads and trends. Eleven years ago, Yamaha developed the reverse-head engine layout with mixed results. The design team stuck with it, making changes year after year. When you’re blazing a new trail, you can’t just copy the other guys. The Yamaha YZ450F was one of a kind, so all the work had to be done in-house. Some years saw major redesigns, while others had minor revisions. Last year was one of those in-between years. It got a new head and a longer rod, along with other less notable revisions. For 2021, there are absolutely no mechanical changes for the YZ450F. That’s never happened before. The fact is that the YZ450F has come a long way. It was a good place to take a rest.

In case you aren’t up to speed on your YZ history, 2018 was the last really big year. That year was a total remake for the frame and motor. Only the overall design philosophy remained. Yamaha also introduced the Power Tuner smartphone app, which allows riders to remap the EFI system quickly through a Wi-Fi connection. It’s clear that Yamaha was ahead of the game on this. KTM, Husqvarna and Suzuki are all going to a similar system for 2021. In those cases, you have to purchase a transmitter separately. Yamaha’s is included with the bike.

The YZ450F is really powerful and really smooth—somehow.
The YZ450F is really powerful and really smooth—somehow.

The fact Yamaha is more or less immune to fads and trends is most apparent when it comes to suspension. The 2021 YZ450F has a KYB shock and a coil-spring KYB fork, just like it has from the beginning. There have been valving and design changes along the way, but Yamaha was the only Japanese company that wasn’t distracted during the era of air forks. Ditching steel springs made forks lighter and less expensive to manufacture, but KYB and Showa never matched the performance of old-fashioned coil springs. That eventually led Honda, Suzuki and Kawasaki back to Yamaha’s way of thinking. Only WP engineers stuck with air, mostly because they started with a better design.

The reason that Yamaha went to the reverse-head engine back in 2010 was to centralize mass. The muffler just barely peaks out from behind the right number plate.
The reason that Yamaha went to the reverse-head engine back in 2010 was to centralize mass. The muffler just barely peaks out from behind the right number plate.

THE GOOD PLACE
We can’t imagine too many riders will be unhappy that the 2021 YZ450F is unchanged. The bike has a devoted following. Most of their points are hard to dispute. Like…

The motor: In the 2020 motocross shootout we declared that the Yamaha had the best motor of the bunch. We would be very surprised if that’s not true again. In terms of absolute horsepower, it’s right on top. With the standard mapping, the Yamaha is more or less tied with the 2020 Honda CRF450R for the honor of being the most powerful production 450 motocross bike so far. The Yamaha is considerably smoother and easier to manage than the Honda, so much so that it’s a little boring. After a brief period of lurchiness at the very bottom, it pulls harder and harder in a very linear way. On top, it revs higher and farther than any other 450. It’s predictable, tractable and fast. Most of the popular maps that are passed between YZ cult members are aimed at providing a little more of a hit somewhere in the powerband. The Honda, KTM and Husky motors all have a little excitement in the middle. They might not be any more effective, but they might be more fun.

The suspension: It’s almost a knee-jerk reaction to praise the YZ450F suspension. It’s been at the top of the MX world for a very, very long time, and it’s as good as ever. The most remarkable aspect of it is that everyone
likes it. Even if you fall outside the average weight and skill level, chances are you will pull off the track happy. If not, you can make it work with a few clicks. Riders generally like the bike with 106mm of race sag in the rear and just a little less compression damping front and rear.

The ergos: Last year Yamaha gave the bike a little attention in the rider compartment. The handlebar was lowered, and the seat was made firmer. Now, the bike is truly comfortable for anyone of average or smaller size. Tall riders might like the optional tall saddle, which provides just a little more leg room.

The clutch: The reason that the YZ450F doesn’t have a hydraulic clutch is because it doesn’t need one. The pull is light and the feel is excellent. A whole generation of pro riders from Jeremy McGrath to Ryan Villopoto sing the praises of the traditional cable-pull clutch, and the Yamaha is proof of how well it can be done. It can heat up and fade, but only when abused. The solution is not to abuse the clutch; the Yamaha’s motor is so good, you don’t need to.

The YZ’s KYB fork remains the standard of the industry.
The YZ’s KYB fork remains the standard of the industry.

THE OTHER PLACE
The main area where the YZ450F doesn’t shine as brightly is in agility. It feels like a big, long, heavy bike. The main reason that Yamaha adopted the reverse-head layout was to centralize its mass. The idea is that if all the heaviest parts are close to the center of the bike, it will feel lighter than it is. Maybe so, but at 239 points, the Yamaha is still 16 pounds heavier than a KTM 450SX-F and 6 pounds heavier than a Kawasaki KX450. It also has a slow-steering feel that some riders like, others don’t. Add it all up and the Yamaha has very little cut-and-thrust in its portfolio of tricks. It likes sweeping lines and power-on cornering.

Yamaha’s Power Tuner is a smartphone-based app that allows you to alter the fuel-injection system. We love it, but it’s time for an update.
Yamaha’s Power Tuner is a smartphone-based app that allows you to alter the fuel-injection system. We love it, but it’s time for an update.

We also hear some very familiar complaints about details, like intake noise, slow refueling because of the filler location and a thin seat. This year we will add one item to the list of small complaints. The Yamaha Power Tuner app is still an impressive technology that moved the whole industry forward. But, it now needs a second generation, just like any software. The interface and feedback aren’t what you expect in these times of intuitive digital devices.

On the flip side, we still love the fact that the air filter stays clean after multiple rides, the levers are everyone’s favorites, the ProTaper bars are strong, the Excel wheels stay round and the Dunlop MX33 tires are excellent. The Yamaha is a well-made motorcycle with top-notch parts. No matter what 2021 brings, the YZ450F will continue to be among the best of its breed. 

2021 YAMAHA YZ450F

Engine type: Electric-start, four-valve DOHC four-stroke
Displacement: 449cc
Bore & stroke: 97.0mm x 60.8mm
Fuel delivery: 44mm Mikuni EFI
Fuel tank capacity: 1.6 gal.
Transmission: 5-speed
Lighting coil: No
Spark arrestor: No
EPA approved: No
Weight, no fuel: 239 lb.
Wheelbase: 58.5”″
Ground clearance: 13.0”″
Seat heigh:t 38.6”
Front tire: Dunlop MX33 80/100-21
Rear tire: Dunlop MX33 120/80-19
Fork: KYB, adj. rebound, comp/12.2”
Shock: KYB, piggyback, adj. preload, comp., rebound, 12.5”
Country of origin: Japan
Price: $9399
Importer yamahamotorsports.com

GREAT!

  • Top suspension
  • Free Power Tuner app
  • Super reliable
  • Very fast
  • Very smooth

LESS THAN GREAT

  • A little big, a little heavy
  • Distracting intake noise
  • Hidden fuel filler
  • Thin seat

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