Yamaha's once-popular YZ450F has been slipping in the polls of late, a situation the factory seems bound to rectify with this newest version that should propel it back into the top tier in the motocross world along with Honda, KTM, and Husqvarna. The 2018 YZ450F sports updated looks to go with its updated features such as the new engine, wireless engine tuning and improved suspension just to name a few. A teeny-tiny battery and lightweight starter system eliminates the old kicker (and the peasants rejoice!) with a new push-button cold-start feature that helps with starts and warmups. For all intents and purposes, this should be considered an all-new machine, so let's check out what Yammy has going on over there and see how it stacks up against the other big boys.

Continue reading for my review of the Yamaha YZ450F.

Design

The new YZ450F sees a head-to-tail revamp with a redesigned front mudguard that leads the way with more compact stiffeners and a different look. Since the fuel tank is actually below the seat, the fuel-tank bump is very slight and only big enough to accomplish its new mission in life as an air-cleaner cover, which is not new but still cool.

Below the faux tank we find another drastic change from the previous gen at the radiator shrouds. Namely, they're much narrower this year, and leave lots of room for kicking a foot forward in the corners. An all-new “bilateral beam” frame is plainly visible as the dearth of body panels leaves little to the imagination with the main spars exposed alongside the engine compartment.

The new bench seat tapers off to nothing over a revised subframe and enlarged muffler guard. It looks much like the '17 model in profile, but when viewed head on or at an angle, the differences become very apparent. Better looking? You betcha, but that's probably the least-important factor on a bike destined for the track, so let's move on.

Chassis

Yamaha recreated the bone structure using extruded-and-welded aluminum members with modified tension pipes that tune the chassis flex without reducing it. In fact, the chassis flexes quite a bit more than did the MY17 units -- too much for some -- and I expect that perhaps the factory will seek a happy medium for next year, but we'll see.

KYB suspension components cushion both ends of the ride with a pair of 48 mm stems with the “Speed Sensitive System” that starts off rather plush for small bumps, but stiffens up through the stroke for the bigger hits. Piston-size gets a boost from 24 mm to 25 mm with the full spectrum of adjustments and 12.2 inches of travel. Out back, a fully-adjustable monoshock tames the motion of the aluminum swingarm with 12.5 inches of travel.

Wire rims mount a 21-inch hoop up front and a 19-incher out back with wave-cut brake discs to haul it down. On paper, the 270 mm front disc and 245 mm rear seem like they should be sufficient, but in truth the bite is rather wooden up front, and it leaves the bike feeling a little under-braked, even for a straight-up dirtbike. Frame and seat design are tuned to make a narrow waist to match the skinnier radiator scoops up front for what is, hopefully, a good balance for all. I mean, who doesn't like slimmer ergos, right?

Drivetrain

It feels a little bit like something from the Twilight Zone to think that the addition of an electric starter would be big news in this day and age, yet here we are. A four-cell, 2.4 amp-hour battery powers the starter, and due to its lithium-ion construction, the battery adds only 1.5-pounds to the bike. I'm sure I don't have to point out how much lighter that is than an old-fashioned lead-acid battery, and I think we can all agree that the extra weight is well worth the push-button starts. The cold-start function works with the single push of a button, and that holds the induction in an enriched state until you blip the throttle to reset the system.

Yammy kicked the cylinders back a few degrees and opted for the forward-intake/rear-exhaust configuration with a 44 mm Mikuni throttle body. A true racebike, the YZ450F comes with a Launch Control System as part of its standard equipment package that gives you controlled and stable holeshots. As cool as that is, it's the new Power Tuner App that turns your iPad or Android device into a digital tuning garage as it connects wirelessly to the on-board computer and allows you to adjust the four-grid ignition and injection maps.

The 449 cc mill runs a 97 mm bore and 60.8 mm stroke with a sizzlin' 12.8-to-1 compression ratio and DOHC with super strong and light titanium poppets. A standard clutch couples engine power to the five-speed transmission with a tough chain final drive.

Pricing

Score the YZ450F in Team Yamaha Blue or white (with a teal seat) for $9,199 with a 30-day limited factory warranty.

Competitors

Honda has some of the hottest stuff on the tracks right now with its CRF450R, so I'm going to go straight for the throat with the top tier competition dirt bike from the Red Riders. Honda presents much the same visage as the Yammy with the typically large, tripletree-mount front fender, low-profile fuel hump and narrow waist at the swale. Like the YZ, the CRF sports a mostly-visible twin-beam frame that is is only partially covered by the radiator shrouds where they project forward from the tank cover.

Rake and trail on the CRF falls out at 27.22 degrees and 4.6 inches against 27.33/4.7 with the YZ, so we're splitting hairs here. Honda goes even smaller on the brakes with a 260 mm disc up front and a 240 mm in back, and its suspension falls off as well with no preload adjustment on the front end, though all the other bases are covered and the rear shock gets full-spectrum adjustability. Not a big difference, but a difference nonetheless.

Honda also embraces the super-light, lithium-ion technology and ditches the old kicker entirely in favor of electric start, so Yammy gains nothing there. The CRF's beating heart is the liquid-cooled, 449 cc thumper that runs a SOHC with titanium intake valves but steel exhaust poppets with a 13.5-to-1 compression ration. Honda's plant does the job well enough, and though it lacks the nifty LCS and dial-a-tuner function found on the YZ, it does come with variable power-deliver modes that allow you to switch up to accommodate changing track conditions. Yamaha turns out to be the prouder of the two, but only by 50 bucks with a base MSRP of $9,149.

He Said

“In the end, brand loyalty will probably win out, but I'm impressed with the Tuning Fork Company's efforts here, and I really dig the phone tuner. Heck of a lot better than the old Power Commanders, that's for sure. I really like it, but it's the racers Yammy has to convince here.”

She Said

My wife and fellow motorcycle writer, Allyn Hinton, says, "These changes in 2018 are welcome improvements. Last year, weight was a problem. The bike was too heavy, though adding the battery this year may offset the weight reductions, and it was too wide to really get serious. New frame, new engine, new suspension, and much slimmer than last year; this really is a whole new bike. Also, I love the ability to change engine mapping from my phone. That's huge and something I think more manufacturers are going to get onboard with. With so many ways to tweek the suspension and engine maping, you really have to take some time and work with it to get it dialed in to you; but once you get it, it's freakin' awesome."

Specifications

References

See our look at the Honda CRF450R.