2018 Yamaha YZ450F First Look | All-New Motocross Motorcycle
On a consistent schedule of renovation every four years, the 2018 Yamaha YZ450F is an all-new racing motorcycle from the ground up that shares only incidental parts with the previous edition. The YZ250F has been enjoying great success with privateers in the Nationals, and Yamaha is hoping for the same level of adoption for the 2018 YZ450F.Here are the essential fast fasts you need to know about the all-new 2018 Yamaha YZ450F motocross and supercross racing motorcycle.
1. Electric starting comes to the YZ450F. It took forever for companies to get electric start onto big-bore four-stroke motocross machines, and now Yamaha joins KTM and Honda in putting this essential feature on their MXers. To minimize the weight gain, the starter is positioned behind the cylinder, and the lithium-ion battery weighs just 1.5 pounds.2. The new YZ450F motor’s power delivery is focused on ease-of-use at lower rpm, and more power on top. The new engine has a straighter intake angle than before, as well as higher-lift cams that open and close sooner. Plus, valve timing overlap is increased by eight degrees over the previous YZ450F. The header pipe is lengthened by 12mm, and the diameter is down three millimeters at the muffler mounting.3. To boost top-end power on the 2018 YZ450F, the engine gets a new piston. The crown is 2.3mm thinner, and the supports redesigned. This lowers the weight of the piston by six grams. Also, the piston pin is now DLC-coated. Additionally, the spark plug electrode is longer to ignite the center of the combustion chamber better, the ECU settings are updated, and the throttle body is now from Mikuni. Plus, there’s a new cold-start button.4. E-start actually means more rear-wheel power. With the battery supplying power, there is less stator drag on the engine at all engine speeds, with the biggest difference at lower rpm.5. The new crankshaft assembly means a smoother ride. Yamaha upped the effect of the counterbalancer. There’s also more crankshaft inertia, though this is offset by less inertia from the stator and rotor.6. A new clutch is designed for smoother operation. Changes include a new pressure plate, new steel plate treatments, and smoother operating springs. For durability, 2nd, 3rd and 4th gears are now one millimeter wider.7. The new chassis focuses on more nimble handling, plus stability. Still a familiar twin-spar aluminum frame, the two main spars are now extruded, rather than hydroformed. The tension pipe, which holds the frame together below the steering head and above the motor, is now forged, rather than extruded. According to Yamaha, rigidity is increased 25 percent vertically, 9 percent horizontally, and 15 percent torsionally. Yamaha claims a smoother flexing of the frame, along with the increased rigidity, makes the YZ450F both more responsive and more predictably stable. Also adding to stability is a three-millimeter increase in trail due to moving the steering stem forward six millimeters.8. Engine mounting is changed for increased traction. The mounting points for the motor are lower and more compact, plus the mounting brackets are aluminum rather than steel. Also, the cylinder is more vertical; it’s tilted back 6.2 degrees, compared to 8.2 degrees last year.9. The KYB suspension is new, but not revolutionary. The KYB Speed Sensitive System fork gets a one-millimeter larger damping piston, and the mid-speed damping valve is now leaf-spring rather than coil. The shock’s piggybank reservoir has a capacity increase of 30cc, while the shock spring is thinner, stiffer, and over seven ounces lighter.10. Ergonomics have been changed. The seat is flatter and lower than before, with the seat almost an inch lower at the rear fender. The footpeg location is unchanged, so there’s a bit less legroom, but your arms will notice that the grips are now five millimeters higher and six millimeter farther forward. Although the bend is the same, the YZ450F gets a new handlebar that has a thinner wall and loses nearly four ounces, much of it at the bar ends for maximum impact.11. All the plastic is new for the 2018 Yamaha YZ450F. Yamaha worked to make rider transitions smoother, with all-new plastic, including a smaller fuel tank (down 1.4 quarts) that still has adequate capacity for long National motos. The frame is a bit narrower at the swingarm, and nearly an inch narrow at the seat/tank junction and the radiator shrouds. The radiator is also more vertically mounted and closer to the center of the frame, even as it has a 4.5 percent larger core. New airflow management better directs air to the radiator.12. Servicing the air filter is easier. There’s only one Dzus fastener on the airbox lid, which is still right behind the steering stem. The filter is now flat and the intake volume is up 29 percent, and needs no tools to be replaced.13. The 2018 Yamaha YZ450F gets sophisticated electronic tuning and diagnostics first used on the YZF-R1S superbike. Using password-protected WiFi, the YZ450F communicates with the Yamaha Smartphone Power Tuner app on your smartphone. Fuel and ignition mapping is now easier, wider ranging, and uses 3D graphics. A race log allows you to quickly switch engine settings for different tracks and conditions. There’s also real-time monitoring of engine speed, throttle position, coolant temperature, air temperature, atmospheric pressure, and battery power. Three user-defined hour-meters make managing maintenance easier. Plus, diagnostic codes help solve motor problems.14. Along with Yamaha Blue, there’s a new color. The white version of the 2018 Yamaha YZ450F now includes teal accents. The Yamaha Blue version gets anodized blue rims, with the White bike going with black rims. Functionally, the two bikes are identical and both run $9199. They should be available around the beginning of August.Photography by Yamaha, and Don Williams2018 Yamaha YZ450F SpecsENGINE
Type: 4-stroke single
Bore x stroke: 97.0 × 60.8mm
Compression ratio: 12.8:1
Fuel delivery: 44mm Mikuni throttle bodies
Valve train: DOHC, 4 valves
Ignition: Transistor controlled
Transmission: Constant-mesh 5-speed
Clutch: Wet multiplate
Final drive: Chain
Frame: Aluminum twin-spar
Front suspension: Fully adjustable inverted KYB Speed-Sensitive System fork; 12.2 inches of travel
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