2016 Yamaha YZ450FX Dirt Bike Review

Off-Road’s Newest Challenger

The YZ450FX is Yamaha’s answer to the KTM 450 XC-F. This bike was designed for competitive use—think GNCC and cross-country racing.Photo by Chris Tedesco

Big blue isn’t pulling any punches. Hot on the heels of the YZ250FX and YZ250X—two very fun, high-performing off-road specific dirt bikes—Yamaha releases another in the “X” line; the YZ450FX. As the name suggests, this motorcycle is based on the 2016 Yamaha YZ450F, very similar to what Yamaha did with the YZ250F and YZ250FX. But, as we will soon explain, this bike is way more than just a motocrosser with an 18-inch rear wheel and kickstand.

To quote Yamaha, the concept of the FX is, “pure, closed-course competition GNCC/Woods racer.” At the recent press introduction, Yamaha had multiple slides in their tech presentation explaining all the demographics of GNCC-type of riders and what they need and want from a bike and, according to Yamaha, the YZ450FX dirt bike and the other X models were built to address that particular set of requirements. They also pointed out that Grant Baylor landed second place in the overall points this year in the GNCC series on a YZ450F in the XC1. Yamaha’s off-road models are becoming similarly categorized as KTM’s in that there are three tiers of off-road bikes: The raciest is the MX/SX bikes (YZ and YZ-Fs), then comes the Cross Country bikes (YZ-X and YZ-FXs), and then the Enduro/Trail bikes (WR-Fs).

A plastic skid plate comes stock on the YZ450FX. We busted ours on a freak rock hit, but experience with the same plate on the YZ250FX has shown us that it is a durable unit that was probably just hit freakishly wrong on our initial test ride.Photo by Chris Tedesco

Since there is no 2015 bike to compare it to, Yamaha framed the introduction of the YZ450FX by comparing it to the bike it is based on, the track-specific 2016 YZ450F. We'll start off with what is the same. All of the updates that the YZ-F got for '16 are on the FX as well, including the larger 270mm front brake rotor, new cam profiles, updated shifter, and revised frame. Also, Yamaha said that, from the rod up, the FX engine and intake is exactly the same as the YZ-F.

As Dirt Rider’s 2016 450 MX Shootout winner, the YZ450F is an amazing machine, and we are glad that Yamaha didn’t deviate to far from that powerplant. But things start to change as you go farther south. The five-speed, wide-ratio transmission is completely different and features a nearly 30 percent wider range compared to the YZ-F’s. First gear is much lower than the YZ-F’s, second is also lower, third is just a touch lower, fourth gear is practically identical, and fifth gear is taller. Yamaha likes to explain this thusly: Imagine that you have a stock YZ450F and you wanted to use a rear sprocket change to match the gear ratios of the YZ450FX. For first gear you would have to add 14 teeth to the YZ450F’s rear sprocket to match the FX’s first gear. Continuing, you’d have to add eight teeth to match second gear, two teeth to match third, zero teeth to match fourth (fourth gear is about the same), and you would have to subtract four teeth to match fifth gear on the FX.

We applaud Yamaha’s choice to keep the same spring rate on the 450FX as the 450F; the rear end has a great blend of comfort and performance.Photo by Chris Tedesco

Moving on to the clutch, Yamaha understands that off-road racing and riding actually calls for more performance and consistency from a clutch. Where the YZ450F’s clutch is more for on/off use, the YZ450FX’s clutch was changed for higher durability, smoother engagement, and a reduced lever pull by 10 percent. How they did this was by reducing the clutch spring set load by 6 percent, adding a judder spring (which works against the springs), while at the same time using more grippy clutch plates than the YZ-F so that the clutch doesn’t loose any feel or power. There are also four steels that are thicker to take more heat and increase durability. Lastly, the shift arm length was reduced 5mm and a brass bushing was added to insure smooth shifting and clutch operation.

Moving on to starting, the FX has a magic electric start button, which is powered by a larger capacity generator. Not only does this new generator produce more power (14v 160w/5000rpm versus the YZ-F producing 14v 95w/5000rpm), it adds more weight to the flywheel. This also makes the left side engine cover different than the YZ-F’s. But, even though there is more inertia from the bigger generator, a different crankshaft and counter-balancer brings the total inertia increase to only 2 percent over the motocross bike. This new counter-balancer also gives the YZ450FX a balance factor of 100 percent over the YZ450F’s 88 percent.

Button, button.... who’s got the button? Yamaha does now, and it works great! This machine starts even better than the YZ250FX when in gear.Photo by Chris Tedesco

To help with cooling, the shrouds are 30mm longer than the YZ-F’s to grab more air at slower speeds and the radiator fin pitch was increased to 4mm. This means that the zig-zagging fins are spaced out more, again to flow more air. Lastly, for more controllable power, the ECU is tuned differently than the YZ-F’s.

Moving on to the chassis, the frame is the same as the YZ450F but it has been “tuned” with different engine mount brackets. The front bracket is 6mm (down from 8mm on the YZ-F) and is a different shape and the upper bracket is also 6mm (down from 8mm). This is aimed at “revising the rigidity balance” yet the fact that the brackets are thinner, we’d say that Yamaha is trying to make the chassis more compliant.

Another thing that Yamaha didn’t change too much was the fork, which we are happy about. The YZ450FX’s front suspension is still the 48mm KYB spring-type fork, just with a lighter spring rate (4.5 N/mm) compared to the YZ450F (5.0 N/mm). The shock spring is unchanged (56 N/mm for both YZ-F and FX) yet there are internal shim stack changes aimed at better trail compliance and comfort. Finally, the most obvious differentiating parts on the FX are the 18-inch rear wheel, plastic skid plate, aluminum kickstand, Dunlop Geomax AT81 tires, and D.I.D O-ring chain. Even with all of these off-road specific new parts, the YZ450FX has an MSRP of $8,890, just $300 dollars more the mxer.

The kickstand is a great touch, and it doesn’t drag or come down on the motocross track. We plan on keeping ours on the bike all year long.Photo by Chris Tedesco

In The Dirt

Our first chance at riding the YZ450FX came at Yamaha’s press introduction in Anza, California. There was a GP-style loop available that featured fun, flowing singletrack, tight rock gardens and ravines, some faster desert-like sections, a mile or two of high-speed cross-country racetrack, and a little bit of motocross mixed in. Although dusty, the varied loop provided several different types of riding in which to evaluate the new machine.

Starting on the YZ450FX is superb; it lights up immediately with a push of the button—engine cold or hot—and it also starts more easily in gear than the YZ250FX does. Similar to the YZ450F, the X model has a throaty exhaust note that is a touch louder to the rider than it is to bystanders; we can already tell that we’d like to try to muffle this a bit more with an aftermarket solution. True to Yamaha’s design, first gear on this bike is VERY low! We actually felt that first was more of a “crawling” gear, and while we didn’t use it a lot (save for those tight ravines and walking-speed rock sections), we were glad that it was there for us. One interesting note is that we felt as though this bike was tougher to shift than the motocross variant; on the FX, the rider must be more deliberate to click into each gear. Whereas the MX bike’s tranny seems to glide into gear, the FX requires you to make sure that each detent is solidly locked (or else the bike simply won’t shift). You get used to this, although it’s definitely a different feel than the motocross bike.

Imagine that you have a stock YZ450F and you wanted to use a rear sprocket change to match the gear ratios of the YZ450FX. For first gear you would have to add 14 teeth to the YZ450F’s rear sprocket to match the FX’s first gear. Continuing, you’d have to add eight teeth to match second gear, two teeth to match third, zero teeth to match fourth (fourth gear is about the same), and you would have to subtract four teeth to match fifth gear on the FX.Photo by Chris Tedesco

The majority of the time spent aboard the 450FX was spent in second or third gear. As expected, the average rider will get into the habit of shifting this bike more than the moto version in order to ensure that the clutch is not constantly being hammered. Still, thanks to a very broad mid-range, there is no “perfect” gear to be in at all times. In other words and although the best way to ride this bike is by shifting frequently, the Yamaha can be revved out in second or lugged in third, and you’ll still remain in the meat of the power. Fourth gear is great for when the trails open up, but again, we found that you have to be cognizant of shifting into a lower gear when those wide-open straights lead into a flowing corner; although strong, the bottom-end power won’t pull quite as low in a higher gear as lazy riders might wish, so you definitely need to click down to at least third on most direction changes. Fifth gear is outstanding for blazing fast fire roads, and the bike is definitely fast enough in its top gear to rid us of the desire for a sixth speed.

Ask any Dirt Rider tester to describe the YZ450F’s engine in one sentence and they’d probably tell you that, “the YZ450F’s engine does everything that a good 450cc powerplant should.” That is to say that it lugs well, it is tuned cleanly, it accelerates strongly, and it has great over-rev. Fortunately, the YZ450FX retained all of these characteristics, but with a slant toward being slightly more manageable and usable for off-road. Twisting the throttle, no matter how fast, fails to reveal a single hesitation or bad patch. Likewise, traction is great even when the dirt is not, thanks to what is a strong but not overly violent delivery profile. One thing to remember when thinking about the Yamaha’s engine is to consider whom this bike was built for. As mentioned, this is a competitive, GNCC-style race bike, and the average trail rider may be surprised by the amount of raw performance contained in the motor. Truth be told, there’s not a lot to be unhappy about motor-wise, but if Yamaha’s engineers put a t-shirt over our heads and threatened to water board us if we didn’t say something negative, we’d probably tell them that they should have made the flywheel even heavier to help combat flame-outs in situations where the bike comes to an abrupt stop (such as lurching onto a rock or slow-crawling over a log). For EnduroCross racing, we’d probably want to run a fully automatic Rekluse clutch to help prevent this low-speed stalling.

The YZ450FX loves to be ridden on fast, GP-like terrain. It simply eats up MX and cross-country style courses, and from what we’ve seen fifth gear is high enough to not need a sixth speed.Photo by Chris Tedesco

On to the suspension, remember that the YZ450FX boasts the same spring rate as the motocross bike in the rear (but with internal changes for compliance), and one rate softer up front. Overall, we think this was a smart move on Yamaha’s part, but we have a few notes; to begin with, the softer fork setting really helps the YZ450FX’s cornering abilities off-road, as it allows the fork to settle more on corner entry, thereby “holding” the fork down lower in the stroke and encouraging the rear end to track in a nice, consistent arc. We’d be willing to bet that a firmer spring rate in the front would have average-speed riders fighting the bike quite a bit more. The downside to the softer springs is that some diving occurs under hard braking, giving the bike a “pitching” sensation that is remedied by two additional clicks of compression on the clickers. The overall action of the fork is purposeful but not fast, and the mid-stroke is incredibly progressive, with outstanding bottoming resistance that is more than capable of tackling even the biggest of jumps on a motocross track. We’ve said it before and we’ll say it again: we are so glad this isn’t an air fork!

The shock on the YZ450FX is excellent. As with the front, the rear end is progressive, settles well, handles big hits with poise, and generally doesn’t pose any issues. Yamaha recommended that the YZ450F run with 100mm of sag; for the FX, 104-105mm is the magic target. For tighter trails, we were happy with 102mm on the rear, and felt that the bike was incredibly balanced front-to-back (save for the aforementioned pitching on hard braking), and that the rear end was plenty squatted all around. Oddly, the mid-corner push that we complained about with the motocross bike is much less noticeable on the off-roader; the changes to the suspension and engine mounts have altered the handling just enough to make this a non-issue. If anything, the 450FX feels a little less inclined to grab traction on flat corners when at a lean, which tells us that it vastly prefers having something to push the tires against.

First gear is more of a "crawling gear" on the YZ450FX. We didn’t use it much, but it came in very handy on tight sections.Photo by Chris Tedesco

One of the few black marks on the YZ450FX’s evaluation form is that the bike feels just as wide as the MX version at the tank. This is something that all riders eventually adapted to; however, there’s no getting around the fact that the shrouds just look and feel slightly bulbous. What they lack in narrowness, however, is made up for by the fact that the hidden gas cap/extended seat design allows the rider to get waaaaaaay up on the tank in turns, something that promotes proper body position in corners. Riders up to 5’10” should be comfortable with the handlebar, although taller pilots will likely feel that the bar bend is a few millimeters too low. The rest of the rider triangle is comfortable, and the cockpit is roomy enough without making you feel as though you’re reaching to adjust your body position. Yamaha’s moto-inspired seat is still more comfortable than some off-road bikes’ saddles!

We like the feel of the 18-inch rear wheel for off-road use, as well as the fact that a trials tire can be slapped on this bike without having to swap out from a 19-inch wheel. The kickstand is plenty sturdy for trailside use, and the spring is strong enough to keep the unit in place on hard hits and big MX-style landings. While there’s not as much braking power here as a KTM, both of the Yamaha’s brakes have great power, and the front is particularly strong yet usable. Thanks to the changes to the clutch, the left lever has a light pull and great feel. We dig the protection offered by the plastic skid plate, but were bummed to discover that we broke it clean off when hitting a rock at just the wrong angle; both of the front mount bolts ripped straight through the front of the plastic, and the rear was just a flippity-flop away from coming clean off. We understand that this is just a glide plate, and we’re already shopping around for a stronger (possibly aluminum) replacement unit.

You may have noticed that the stock YZ450FX does not come with hand guards. We added a set of aftermarket Cycra units to ours, but still wish that the Japanese engineers cared enough about our fingers to build the bike with them installed!Photo by Chris Tedesco

Now, for the question everyone is wondering: is this bike better than a KTM 450 XC-F? That isn’t something we can definitely answer until we have both machines in the same place at the same time, but we can tell you this: the YZ250FX kicked the pants off of the KTM 250 XC-F in our 2015 off-road comparison. Our prediction is that the Yamaha will win in both the suspension and engine categories when placed against the KTM, but the Austrian steed might have a leg up in the fit-and-finish category—a hydraulic clutch is difficult to ignore! We will most certainly get these two machines in the same place soon for an official showdown, but for now, let’s just call it “to be determined” with a very good chance that the Yamaha will come out on top.

Yamaha was in a generous mood during our day of riding, and when we left the press introduction after several hours of testing, our 2016 YZ450FX test bike was tied into the back of the Dirt Rider truck. The next step is to ride this machine on a variety of local tracks and trails, and we will absolutely be trying some different modifications before ultimately putting it back to stock form and giving it a fair shake alongside the KTM 450 XC-F. Until that grudge match goes down, you can ask us any questions that you like at facebook.com/dirtridermag, and we will do our best to answer them.

You can moto the YZ450FX like normal with hardly any faults or ill effects. The fork is a little soft and divey on corner entry, but even that this makes for excellent tracking in turns, with less mid-corner push than the motocross bike.Photo by Chris Tedesco

Here are a few answers to some select questions from the initial round of queries about this bike, as asked by our loyal readers on Dirt Rider's Facebook:

Joel Aidan asks: I wanna know how to get the job of test riding all new Yamahas!

Answer: The process for getting a job as a Dirt Rider test rider is similar to getting into a fight club; you have to be invited by a current member, and once you're there, you can't really talk about it! In all seriousness, our test riders go through a comprehensive vetting process where they prove to us that they are qualified to evaluate motorcycles in an unbiased manner. This doesn't mean you have to be fast, but you do have to be good. If you think you have what it takes, send us an email at drmail@bonniercorp.com and explain why!

Krzysztof Tomasek asks: How good is it on a motocross track?

Answer: Really good, Krzysztof! The stock YZ450FX is more than capable of tackling anything than a standard motocross track has to throw at it. If you're looking for faults, we can tell you that the fork will dive more on corner entry than the MX bike, and that on high-speed, choppy downhills, you may even experience a bit of headshake due to the fork packing more. There again, this can be somewhat remedied with the clickers. For everything else, the bike is totally capable on a motocross course, and the electric start is a definite advantage!

Big doubles, no troubles! Our YZ450FX loved this 70-foot jump, where it definitely did not feel as though we were riding an off-road bike!Photo by Chris Tedesco

Adam Preston asks: Can I have it when you guys are done with it?

Answer: Maybe. All of our old test bikes go back to the manufacturers at the end of the year, and so long as our YZ450FX's VIN isn't too low (which could signify that it's a "crusher" doomed for destruction), there's a good chance that this bike will be auctioned off to a dealer. If you're lucky enough to track it down, it's entirely possible that you could end up with this thing sitting amongst the used bikes outside of your local bike shop—we've seen it before. Should you be fortunate enough to track this bike down and buy it, rest assured that we actually take great care of our test bikes. It'll be ridden hard, but it'll also be treated like one of our personal bikes, which means frequent oil changes, filter cleanings, and great mods. Whoever owns this bike after us will be stoked!

Nick Trainor asks: Does it come in orange?

Answer: No, Nick—and that's the point! Yamaha intended to offer riders like you and I with another option to choose from when selecting an off-road bike. I'm sure you've been to a GNCC or National Enduro in the last year; it is a sea of orange. Yamaha simply realizes that not everyone wants to go with the crowd, and for that reason they have jumped even deeper into the off-road game. Now, depending on how this bike stacks up against the KTM, some riders may be wishing that the 450 XC-F came in blue!

Even with all of these off-road specific new parts, the YZ450FX has an MSRP of $8,890, just $300 dollars more the MX model.Photo by Chris Tedesco

Stewart Rogers asks: Why no six speed?

Answer: Yamaha didn't feel that a sixth gear was necessary, and after riding the bike, we totally agree. A stock YZ450F motocross bike will go nearly 80 MPH in stock form; we haven't put a GPS on the YZ450FX yet, but we're sure that it's even faster than the MXer in a straight line. I don't know about you, but I definitely don't need my off-road bike to do 90 MPH!

Doug Williams asks: How does it compare in the woods to the two-stroke 300s?

Answer: We haven't yet ridden this machine back-to-back with a two-stroke, but we predict that in tight sections, a 300 will be easier to ride; although the YZ450FX isn't top-heavy, it isn't as light feeling or complaint on direction changes as a two-stroke. Also, the 300 two-stroke will definitely lug lower, and that also makes it quieter, which is a very good thing on public trails. But in terms of vibration, the four-stroke is going to be vastly more comfortable, and the mid-range is much broader, with a more usable transition between various portions of the powerband. On nasty rock sections, the 300 may very well be the champ, but we'd bet that the thumper will take the cake everywhere else.

Brian Kimmitt asks: Why do we need this thing when the KTM XC lineup already exists?

Answer: Variety is the spice of life, Brian. Even if cheeseburgers are your thing, knowing that a chicken sandwich is available can bring freedom of choice to an otherwise one-sided option. It's important to note that Yamaha didn't just built an XC-F; they built their take on an XC-F, and that take may very well be better in terms of performance than KTM's. And even if it's not, it's incredibly cool that a Japanese manufacturer has provided us with yet another qualified option. Both the YZ450FX and the KTM 450 XC-F are amazing machines, and they will push each other to higher levels of performance, which means that the customers are the eventual winners. Think about how cool it would be if this bike forced Honda, Suzuki, and Kawasaki to jump back into the off-road game—we'd have a ton of bikes to choose from, and they wouldn't all be owned by the same company, either!

Brian Zeman asks: When can you deliver to my house?

Answer: Tomorrow. If, that is, you live and work at the Dirt Rider shop in Southern California. The YZ450FX is in need of a good bath, a weigh-in on our official scales, and an air filter change. You can handle that, right?