Kawasaki steps up with an all-new 2016 KX450F. Has the green gang built the best KX450F ever?
Stiffer competition from the likes of KTM, Husqvarna and Yamaha have left the KX450F, which was last presented as an all-new design 4 years ago, showing its age. Minor updates have helped the big green machine remain as a competent contender in the brutal 450cc class, but Kawasaki knew all along that the time was coming when it would need an all-new KX450F if it was to get back to the good times it enjoyed as the king of the 450cc mountain earlier this decade.
That time is now. Say hello to the all-new 2016 KX450F, a 450cc class wrecking machine that boasts a new engine that is lighter and more powerful, as well as a new chassis that is also lighter and slimmer. Kawasaki looked anywhere and everywhere it could to shave weight from the KX450F, and the hard work paid off with a machine that is 7.5 lbs. lighter than the previous model and better in just about every way.
Power wasn’t the problem, but weight was, so Kawasaki’s engineers endeavored to design an engine that was not only quicker but also lighter. Thus, the KX450F’s fuel-injected DOHC four-stroke Single is new from the cases up. The new cases are shaped differently, they’re lighter and they’re thinner, yet Kawasaki claims that they don’t sacrifice rigidity. There’s no mistaking the redesign, as the engine lower half of the engine looks more compact. A perfect example of this strategy can be found in the oil pump placement. Kawasaki engineers moved the oil pump from the left case to the right case and integrated the scavenge pump and the feed pump into one unit to save space. The new cases were also designed to accept an offset cylinder that is pushed forward 8.5 mm to reduce friction by reducing piston-to-cylinder-wall thrust for less drag and easier power production.
There are some similarities to the old engine—although very few: The 2016 KX450F retains the same 449cc displacement, 96 x 62.1mm bore and stroke and 12.8:1 compression ratio as the 2015 KX450F. However, the new motor features a host of new parts, including a cylinder head with redesigned intake ports that are straighter than before to provide a more direct shot of the incoming mixture into the combustion chamber. Inside the head, 36mm titanium intake valves are employed to lighten the valvetrain, and Kawasaki says that the valves feature the same design parameters as the intake valves in its supersport engines, giving them a slimmer throat angle and reduced recesses. The KX450F also features redesigned intake and exhaust camshafts hat have been reshaped to create a slimmer internal diameter, which provides a scant .5 oz. weight savings. A new intake cam sprocket shaves an additional .7 oz. of reciprocating weight from the engine as well. The cam specs are the same as the previous KX450F, but Kawasaki revised the intake cam timing, advancing it 2° to give the bike better lunge off the bottom.
Other new pieces include a new version of Kawasaki’s pioneering F1-style bridged-box bottom piston, which was done to match the new valve shapes. The crankshaft is also redesigned with a different shape, and it saves 1.9 oz. of weight from the reciprocating group. Likewise, the counterbalancer gears have also been lightened to reduce another 1.4 oz. of weight.
Kawasaki engineers also worked to improve air flow into the engine and improve throttle response by completely redesigning the KX450F’s airbox. The new structure pulls-in fresh air through a pair of air intakes located at the back of the seat, and Kawasaki did away with all of the steel parts used in the previous design to not only save weight but also to help reduce intake noise. Even greater noise reduction is attained via the KX450F’s exhaust system, which incorporates a new header design with a resonator that is designed reduce sound emissions by 2 decibels while also accenting the engine’s low-end grunt.
The KX450F’s DFI fuel-injection has also been updated with a new 43mm Keihin throttle body that is lighter and more compact than the previous version, some of the weight reduction coming via the elimination of the previous model’s throttle linkage. A revised fuel pump also facilitates the use of a lowered 1.66-gallon fuel tank to improve the bike’s center of gravity. Of course, the KX450F’s ECU retains Kawasaki’s first-in-class Launch Control feature, and the ignition curve can still be altered by plugging different DFI couplers to suit the booming motor to match track conditions and/or riding style. The engine ECU is also fully programmable via Kawasaki’s accessory handheld KX FI Calibration Kit, which can store up to seven preset maps.
To put the new KX450f through its paces, we trucked up to the High Desert to visit Snrise MX Park in Adelanto, California. Like the Kawasaki, the facility has gone through a complete redesign, and we figure that the new track would be an excellent place to evaluate the KX450F.
It only took a few laps aboard the new KX before expert moto tester Ryan Abbatoye came back impressed. The new KX450F engine churns out fluid and plentiful low-end power without stretching the rider’s arms. Right behind that, however, is an eyeball-flattening mid-range that pulls hard, and the engine keeps on pulling all the way to its rev limiter. The killer mid-range and long-legged top-end mean that you won’t have to shift the KX450F’s slick five-speed transmission all that much. Abbatoye also noted that the KX has a much, much better-sounding exhaust note than the previous models despite Kawasaki’s claim that it is also quieter than the old exhaust system—something Kawasakis have been criticized for in the past. Throttle response is also excellent regardless of rpm or engine load.
But what really impressed about the new KX450F is its handling. Previous-generation Kawasaki 450s have had a “steer with the rear” handling character in which the rider was forced to get on the throttle to help the machine carve through a turn. The new KX450F’s front end is far less vague, delivering light and pinpoint accurate steering manners with excellent front-wheel traction. That’s because the 2016 KX450F features a completely new aluminum perimeter chassis that checks in about 1 lb. lighter than the previous model but is a much narrower through the middle, thanks to its 6mm slimmer spars. It could have been lighter still, but the KX450F’s subframe uses thicker wall material than in the past for improved strength. Even so, a revised aluminum swingarm, drops another 7.8 oz. while also boasting improved rigidity via a larger pivot diameter. The overall chassis weight savings is 3.5 lbs., even with addition of a new forged downtube that is stiffer and certainly helps the chassis to be more reactive to steering input. The frame geometry numbers are as follows: 28° rake and 4.9 inches of trail.
The chassis is designed to concentrate more of the KX’s 240-lb. wet weight forward to really help plant the front end or hold a line in a rut or through a high-speed sweeper, and it definitely does that. The best part is that this improved steering capability doesn’t come at the expense of straight-line stability at motocross speeds. Improved handling is definitely the 2016 KX450F’s strongest attribute.
“It steers really well,” Abbatoye said. “Previous KX450F’s were always stable, but they were more work to hustle through corners than this one is. That stability has always made Kawasakis great bikes for riding fast in the desert, so it would be interesting to get this one out in the desert at really high speeds to see if more weight on the front end has an effect on its stability.”
Abbatoye also mentioned that part of the KX450F’s handling feel can be attributed to its slimmer cockpit layout. The narrower frame spars really give the rider a lot more room to work with when scooting around on the machine to set it up for turns. Its seat is narrow but comfortable, with a flat profile that makes sliding fore and aft easy. The slimmer sides also help shorter riders deal with the KX’s lofty 37.8-inch seat height. On top of that, the KX450F’s ergonomics are more adjustable than most, with new footpegs that can be lowered 5mm to give taller riders more leg room as well as handlebar clamps that offer a total of 35mm of adjustment to dial-in the KX’s comfort for just about anyone.
Of all the improvements that Kawasaki has made to the KX450F, its suspension performance was the one that took the most time to get used to. Previous KX450Fs had a reputation for being stiff and unyielding over square-edged bumps, but Kawasaki has attempted to address this via revised settings in its Showa suspension components to give the bike a plusher ride. The KX’s 49mm Showa Separate Function Fork, Triple Air Chamber (SFF-TAC) has been updated for 2016 with new low-friction seals and updated valving for better action. The fork itself is an impressive piece of suspension engineering. The left leg offers 22 positions of compression damping adjustment and 20 positions of rebound damping adjustment while further fine tuning is possible by adjusting the three air chambers in the right fork leg with the accessory 0-300 psi digital air pump that is supplied with the machine at the time of purchase.
Out back, the KX’s Uni-Trak rear suspension system has received a revised linkage ratio to work in concert with the new chassis. Its Showa piggyback reservoir shock features 19 positions of low-speed compression damping, four turns of high-speed compression damping and 19 positions of rebound damping. Typical of most off-road and motocross machines, the spring also features spring preload adjustability. For 2016, Kawasaki opted for a softer rear spring, going from 53 Newton-meters to 52 Newton-meters, again, for a plusher ride.
On the track, Abbatoye found the 2016 KX450F to be a lot plusher—in fact, a little too plush for a rider of his expert-level skills. It didn’t take long to realize that the big KX was blowing through its suspension travel rather easily at both ends when landing from big jumps and blasting through high-speed whoops. A suspension adjustment was in order.
Kawasaki’s “Standard” air presssure specs for the three chambers are as follows:
Inner chamber: 174 psi (12 BAR)
Balance chamber: 203 psi (14 BAR)
Outer Chamber: 14.5 psi (1 BAR)
To prevent the fork from bottoming, we opted to adjust the air pressures in the three chambers, which is an easy chore with Kawasaki’s special high-pressure pump, which is supplied to new KX owners. We went with Kawasaki’s recommended “Hard” pressure settings:
Inner chamber: 189 psi (13 BAR)
Balance chamber: 218 psi (15 BAR)
Outer Chamber: 14.5 psi (1 BAR)
To stiffen up the shock action, we went out ¼ turn on the high-speed damping to help keep the rear wheel planted better and soak up bumps when accelerating out of a bumpy corner but added a few clicks of low-speed compression damping to slow the shock down over big hits. The combined suspension changes were a definite improvement, although Abbatoye commented that heavier riders or complete animals may want to be even more aggressive in firming up the KX’s suspension.
The new suspension settings allowed Abbatoye to attack the Sunrise track even harder, so he was glad that Kawasaki’s 270mm front and 240mm rear brakes and Nissin calipers do a great job of hauling the KX450F down from speed. The KX’s brakes deliver plenty of power and far better feel than some of the models we’ve tested lately.
If you’re fan of green machines, you can also rejoice that the 2016 KX450F looks as good as it works, with all-new bodywork that gives the KX an almost anorexic look. Part of the slim appearance is due to new V-shaped radiators up front that allow the radiator shrouds to be moved in closer to the tank, and Abbatoye said that this is another contributing factor in the KX’s roomy layout.
“Bottom line, I like it a lot more than old one,” he said.
The 2016 KX450F is indeed an improved machine, and all of these improvements don’t put a substantial hurt on the customer’s wallet. At $8,799, the 2016 KX450F is only $100 more than the 2015 KX450F. That said, we expect to see a lot of green flowing into Kawasaki dealer coffers next year because we expect to see a lot of new green out on the nation’s motocross tracks.
2016 Kawasaki KX450F Specifications
Engine: Liquid-cooled, fuel-injected, DOHC, four-stroke
Bore x Stroke: 96 x 62.1mm
Compression Ratio: 12.8:1
Fuel System: DFI® with 43mm Keihin throttle body
Ignition: Digital DC-CDI
Final Drive: Chain
Frame: Aluminum perimeter
Rake/Trail: 28°/4.9 inches
Fuel Capacity: 1.66 gallons
Front Suspension: 49mm Inverted Showa SFF-Air TAC Separate Function front Fork with Triple Air Chamber, DLC coated sliders, 22-position compression and 20-position rebound damping adjustment, 12.2 inches of travel
Rear Suspension: Uni-Trak® linkage system and Showa shock, 19-position low-speed and 4-turns high-speed compression damping, 22-position rebound damping and fully adjustable spring preload, 12.4 inches of travel
Front Tire: 80/100-21
Rear Tire: 120/80-19
Front Brake: Single semi-floating 270mm Braking petal-style disc with dual-piston caliper
Rear Brake: Single 240mm Braking petal-style disc with single-piston caliper
Overall Length: 86.4 inches
Overall Width: 32.3 inches
Overall Height: 50.8 inches
Ground Clearance: 13.6 inches
Seat Height: 37.8 inches
Claimed Curb Weight: 239.6 lbs.
Wheelbase: 58.9 inches
Fuel Capacity: 1.66 gallons
Color Choices: Lime Green