Will more refinement keep Yamaha’s class-conquering YZ450F at the top of the heap?
Yamaha’s YZ450F turned a major corner in 2015.
After a complete redesign in 2014 to get the radical reverse inclined-motored YZ open-classer to the top of the 450cc motocross mountain, Yamaha finally found the right combination of power and handling to make the YZ450F a class favorite, claiming the vast majority of shootout wins in the enthusiast pubs in 2015. Even better for the BLu Cru, the 2015 YZ450F model has also been the top-selling 450cc motocross machine this season, a testament to its newfound popularity.
But apparently good wasn’t good enough, because for 2016 Yamaha’s best 450cc motocross machine is even better. At least that’s what our hot laps aboard the 2016 YZ450F revealed during Yamaha’s U.S. press intro yesterday at Competitive Edge Motocross Park in Hesperia, California.
Just as with the 2015 machine, it isn’t a radical overhaul but rather subtle changes that make the 2016 model better than ever. Minor revisions to “Big Blue,” in 2015 included an ECU tweak to fatten up its fuel-injection at low rpm (for a smoother throttle feel), bigger valves, lower motor mount changes, a slight gearing change, stiffer fork springs and suspension setting refinements. All of these helped to put the YZ450F on top, but for 2016 Yamaha elected to refine the engine, chassis flex and suspension specs even further while also adding a new trick in the form of the a new Launch Control System to help harness the 450cc’s thunderous power out of the starting gate.
And that’s not all, as the 2016 YZ450F is even more user-friendly than before, courtesy of camshaft changes made to its 449.7cc, liquid-cooled, fuel-injected DOHC engine. Yamaha seems to have found a sweet spot with the 450F’s 97.0 x 60.8mm bore and stroke and 12.5:1 compression ratio, and these specs are unchanged for 2016, but to give the motor more robust low-end torque and a smoother transition through the rev range without hurting its mid-range and top-end performance, the 2016’s intake and exhaust cams feature different lift, duration and lobe centers that change the timing with which the 450F’s titanium intake and exhaust valves open and close. According to Yamaha these are the specs for the 2015 and 2016 cams.
2015 YZ450F Intake Cam
Open: 37° BTDC
Close: 77° ATDC
Lobe Center: 110° ATDC
2016 YZ450F Intake Cam
Open: 30° BTDC
Close: 78° ATDC
Lobe Center: 114° ATDC
2015 YZ450F Exhaust Cam
Open: 73° BBDC
Close: 43° ATDC
Lobe Center: 105° BTDC
2016 YZ450F Exhaust Cam
Open: 70° BBDC
Close: 38° ATDC
Lobe Center: 106° BTDC
The difference in these numbers may not seem all that radical, but it makes a noticeable difference in the performance of the YZ450F. According to DBC’s ace test rider, Ryan Abbatoye, the 2016 YZ450F comes off the bottom smoother and with more authority than the 2015, making it easier to get a good drive out of corners. The extra grunt also makes for a more seamless transition to the top-end rush. The slightly less explosive power delivery should make the 2016 more useable for the vast majority of riders, and Abbatoye said that the bike feels just as strong through the middle and on top as last year’s YZ, although he also detected that the 2016 doesn’t rev quite as quickly as the 2015 did. Either way, the Yamaha delivers more power than most normal people can deal with, and the slightly abnormal Abbatoye had a lot of fun shredding berms and soaring off of Comp Edge’s numerous jumps aboard the YZ450F. The Yamaha is clearly still a beast, just a more manageable beast
The YZ450F’s new Launch Control System (LCS) is designed to offer the same benefit as the systems found on competitive models—to get the rider out of the gate more effectively. The LCS works in concert with the ECU to briefly retard ignition timing and thus limit wheelspin on slippery concrete or slick dirt launch pads. It’s engaged by pressing a button on the left handlebar, and a flashing red light denotes when the system is armed. The system works in either first or second gear, and the ECU reverts to the standard map when the rider shifts into third gear.
Abbatoye spent some time getting to know the LCS at Comp Edge. On the track’s slick concrete starting pad, the LCS made second-gear starts much easier as the machine hooked up and shot off the starting line more quickly than it did when Abbatoye made his baseline starts with the system disarmed. However, in the dry, loose, deep, dirt just ahead of the starting gate, the traction was too good and the system only tended to flatten out the engine’s power, making it less effective. Abbatoye found that he was better off simply using the old-school, slip-the-clutch method to control wheelspin rather than relying on the LCS to do it for him. The Launch Control System certainly works when conditions are really slippery, but we’d call it a qualified success.
Improvements have been made to both the YZ450F’s clutch and five-speed transmission for 2016. a new machining process is claimed to make the surface on the clutch basket as flat as possible in an attempt to improve the clutch engagement feel, and the transmission receives a new shift stop lever design and shifter dog shape. The new shift stop lever increases spring load by 20 percent compared to the previous model, which Yamaha says will make shifting more precise under power and also reduce the chance that the rider will catch neutral on the 1-2 upshift. We never had an issue with the way the YZF shifted in 2015, but Abbatoye noted that the 2016’s shifting feels smooth and precise especially under full-throttle upshifts without using the clutch. The only other internal engine change Yamaha engineers made for 2016 was to add six holes to the water pump impeller to improve pressure distribution within the pump and thus make the system less prone to blowing a water pump seal.
Yamaha tweaked the YZ450F’s chassis to improve its handling characteristics for 2016, once again altering the flex character of its Bilateral Beam aluminum chassis but also adjusting the fork offset to deliver more front-end feel and better turning stability. To attain the desired rigidity, the 450F’s frame spars have been made 12mm wider at the swingarm pivot and also added new top motor mounts that feature more of a v-shape than the previous y-shape and a thicker cross section (8t vs. 6t) than the 2015’s mounts. Lastly, Yamaha incorporated new footpegs that are 5mm lower than the previous models without actually changing the footpeg mount on the frame. This was done to increase rider comfort and also, says Yamaha, to lower the YZ450F’s center of gravity.
To directly address the front end feel in the corners, the 2016 YZ450f gets a new top fork clamp with 25mm of offset–3mm more than the previous version–to effectively pull the forks in closer to the steering tube. However, at the same time, the 2016 model’s shock spring is softer—Yamaha dropped its spring rate from 58Nm to 56Nm, effectively allowing the rear end to settle more under a load, which actually increases trail. the YZ450F’s 58.3-inch wheelbase is the same as last year’s bike.
Depending on what he eats for breakfast, Abbatoye weighs 160-170 lbs. in full gear. He commented that compared to the 2015, the 2016 YZ450F delivers a more balanced feel in the corners and is more stable. Whereas last year’s model tended to sit with more of a tail-high, stinkbug stance, the 2016’s chassis feels more settled while still delivering sharp turning manners. And while we noted a slight nervousness in the 2015 YZ front end when diving into corners, the 2016 is far more confidence-inspiring. Initially, he did notice the twitch again, but it was eliminated completely by adding one click of rebound damping to the fork. After that, Abbatoye was able to charge Comp Edge’s bermed and flat corners harder because the ’16 simply goes where you point it more precisely than before and with minimal effort. Abbatoye noted that it also dutifully follows deep ruts without any issues.
The spring change to the YZ450F’s KYB piggyback (which offers preload, high- and low-speed compression damping, and rebound damping adjustability) shock also yields a more harmonious interaction between the front and rear suspension in rough ground. Up front, Yamaha has stuck with its tried-and-true 48mm KYB Speed Sensitive System (SSS) fork, which features good ol’ steel coil fork springs instead of air, and we applaud them for it. The fork is easy to tune and offers ample compliance over small bumps while resisting bottoming over big jumps. The revised suspension and chassis settings had our test unit tracking straight and true through Comp Edge’s whoop section.
The 2016 YZ450F’s new 270mm petal-style front disc brake is about the only improvement that leaves us indifferent. While it is 20mm larger than last year’s front brake, Abbatoye said that he really didn’t notice any increased performance out of it when compared to the previous front brake. The brake delivers a linear feel, and its stopping power is more than adequate, but it’s nothing that is going to make Honda or KTM run back to the drawing boards.
Then again, maybe the 450F’s ergonomics will. Yamaha’s strict attention to mass centralization allows for a roomy cockpit with a flat, narrow seat and practically seamless transition to the top of the “fuel tank” (which is actually the top of the airbox, since the 2-gallon tank is under the seat). Abbatoye quickly noted that lowering the footpegs 5mm makes a substantial difference in comfort, allowing him to feel completely comfortable when whipping the bike around to his heart’s content.
Yamaha continues to chisel away at the YZ450F, making small improvements that have turned out to yield huge dividends in terms of its performance and popularity, and 2016 is proof that you can make a great bike better without having to go through a complete redesign.
2016 Yamaha YZ450F Specifications
MSRP: $8590/$8690 (Limited edition 60th Anniversary colors)
Engine Type: 449.7cc liquid-cooled DOHC 4-stroke; 4 titanium valves
Bore x Stroke: 97.0 x 60.8mm
Compression Ratio: 12.5:1
Fuel Delivery: Yamaha Fuel Injection (YFI), Keihin 44mm throttle body
Ignition: TCI (Transistor Controlled Ignition)
Transmission: Constant-mesh 5-speed; multiplate wet clutch
Final Drive: Chain
Front: KYB Speed-Sensitive System, inverted fork; fully adjustable, 12.2-in. travel
Rear: KYB monoshock, adjustable preload, compression and rebound damping, 12.4-in. travel
Front: 270mm rotor disc brake w/two-piston caliper
Rear: 245mm rotor disc brake w/single-piston caliper
Front: 80/100-21 Dunlop MX52-FA
Rear: 120/80-19 Dunlop MX52
Seat Height: 38.0 in.
Wheelbase: 58.3 in.
Ground Clearance: 13.0 in.
Fuel Capacity: 2.0 gal.
Claimed Wet Weight: 247 lbs.
Color: Team Yamaha Blue/White; Limited-edition 60th Anniversary Yellow/Black/White