2018 Yamaha Motocross and Off-Road Models Announced | Dirt Rider

2018 Yamaha Motocross and Off-Road Models Announced

Details on the all-new Yamaha YZ450F, updated WR250F and WR450F, YZ250F, YZ250FX, and YZ450FX.

2018 Yamaha YZ450F

The 2018 Yamaha YZ450F is all-new from the ground up.

Courtesy of Yamaha

Yamaha gave the media a sneak peek at their 2018 motocross and off-road models including the all-new YZ450F. Yamaha's flagship motocrosser features an all-new engine equipped with electric-start and tuning capabilities from a smartphone. The frame has been completely redesigned and the KYB SSS front fork and rear shock have received internal changes as well. Additionally, the bodywork of the YZ450F has been slimmed down in a number of areas including the airbox, fuel tank, seat, and plastics.

2018 Yamaha YZ450F

Yamaha kicked the kickstarter to the curb and went with an electric-start system on the 2018 YZ450F.

Courtesy of Yamaha

2018 Yamaha YZ450F, engine

The all-new engine has less of a cylinder incline and is more upright by 2 degrees from the previous generation model.

Photo by Andrew Oldar

2018 Yamaha YZ450F, engine cases

The bottom end of the engine has received a complete overhaul beginning with new engine cases. In addition to a new crankshaft, the gears of the transmission have a wider surface area and the clutch has a stiffer outer pressure plate. The shift lever and shift selector drum have also been changed.

Photo by Andrew Oldar

2018 Yamaha YZ450F, piston

The new engine utilizes a bridge box piston that has a compression ratio of 12.8:1, up from 12.5:1 in 2017. The piston is approximately 6 grams lighter and the crown thickness has been reduced by 2.3mm. Additionally, the piston pin receives a DLC coating, which Yamaha claims reduces friction.

Photo by Andrew Oldar

2018 Yamaha YZ450F, cylinder head

The cylinder head features a straighter intake port shape and the high lift cam profiles increase valve opening by 0.5mm at the intake valves and 0.4mm at the exhaust valves. As a result of this, the valve timing over-lap is wider by 8 degrees.

Photo by Andrew Oldar

2018 Yamaha YZ450F, throttle body

The 2018 YZ450F features a new 44mm Mikuni throttle body, which Yamaha claims is 12 percent lighter than the previous Keihn unit. The throttle body features a push type knob cold-start system, which can be turned off by closing the throttle so the rider doesn’t have to reach down to turn it off.

Photo by Andrew Oldar

2018 Yamaha YZ450F, battery

The electric starter system utilizes a compact starter motor and a lithium battery that Yamaha claims weighs 1.5 pounds. The YZ450F no longer has a kickstarter.

Courtesy of Yamaha

2018 Yamaha YZ450F, frame

The all-new bilateral beam frame features redesigned upper frame bracing, rear frame spars, and new engine mounts.

Courtesy of Yamaha

2018 Yamaha YZ450F, airbox

The airbox on the 2018 model (right) in comparison to the 2017 model (left). In addition to being slimmer, the new unit has air ducts integrated with the shroud and only has one Dzus fastener holding it in place, down from three in 2017. The air filter is now a flat design as well.

Photo by Andrew Oldar

2018 Yamaha YZ450F

The width of the new fuel tank has been decreased by 16mm at the front section and the capacity has been reduced from 1.9 gallons to 1.6 gallons. Further back on the bike, the seat has been narrowed by 18mm in the saddle and tank area.

Courtesy of Yamaha

2018 Yamaha YZ450F, radiators

The radiators are mounted six degrees more vertical and 6mm closer to the frame.

Photo by Andrew Oldar

2018 Yamaha YZ450F

The KYB SSS forks have new internals including an increase from 24mm to 25mm in the cylinder and piston size. Additionally, the mid-speed valve has been changed from a coil-spring type to a leaf-spring type.

Courtesy of Yamaha

2018 Yamaha YZ450F

The 2018 YZ450F comes stock with blue rims inspired by the race team. In addition to the color change, Yamaha claims the wheels are lighter by 40 grams in the front and 70 grams in the rear.

Courtesy of Yamaha

Yamaha Power Tuner App

Replacing the GYTR Power Tuner is the new Yamaha Power Tuner App. The app works on iOS and Android devices and allows for fuel and ignition timing changes. Uploads to the YZ450F are done via the bike’s onboard WiFi system.

Courtesy of Yamaha

2018 Yamaha YZ450F

The 2018 Yamaha YZ450F is available in two colors - Team Yamaha Blue or White (pictured).

Courtesy of Yamaha

2018 Yamaha WR250F

The WR250F features a number of updates to the engine and chassis. The changes in the engine include new cylinder head ports with a straighter intake, higher lift camshafts, a new piston, piston pin, piston oil sprayer, connecting rod, air funnel, throttle body joint, head pipe, and ECU calibration. The final revision to the engine is a new bushing on the clutch arm of the engine case. Changes made to the chassis include a new main frame, engine mounts, fork seal scraper, and the fork's pressure piston. The WR250F now comes stock with Dunlop MX3S tires and the kickstarter lever has been removed, but is available as an accessory.

Courtesy of Yamaha

2018 Yamaha WR450F

The changes made to the 2018 WR450F are the same as some of those found on the 2018 WR250F including a new fork seal scraper, a change in the shape of the fork's pressure piston, Dunlop MX3S tires, and the absence of a kickstarter.

Courtesy of Yamaha

2018 Yamaha YZ450FX

The YZ450FX no longer comes stock with Dunlop AT81 off-road tires and now uses Dunlop MX3S rubbers.

Courtesy of Yamaha

2018 Yamaha YZ250FX

The YZ250FX now comes stock with Dunlop MX3S tires as well.

Courtesy of Yamaha

2018 Yamaha YZ250X

The single change made to the 2018 Yamaha YZ250X is that it now comes stock with blue rims.

Courtesy of Yamaha

2018 Yamaha YZ250F

The YZ250F is largely unchanged and available in two color options - Team Yamaha Blue or White (pictured).

Courtesy of Yamaha

2018 Yamaha YZ250

All of the motocross models now come stock with blue rims. This includes the YZ450F, YZ250F, YZ250 (pictured), YZ125, and YZ85.

Courtesy of Yamaha

2018 Yamaha YZ125

Stock black rims are a thing of the past on Yamaha's two-stroke motocrossers, as each of the bikes now come with the race team inspired blue rims, including the 2018 YZ125.

Courtesy of Yamaha

2018 Yamaha YZ85

Blue rims aren't just reserved for the full-size Yamaha machines. The 2018 YZ85 gets some blue rim action as well.

Courtesy of Yamaha

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