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2018 Yamaha YZ450F Review | FIRST IMPRESSION

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The 2018 Yamaha YZ450F is unquestionably one of the most highly anticipated bikes of the year. The blue machine is all-new for 2018 and features a number of major changes to the engine, chassis, and bodywork. The engine is now equipped with electric-start, is positioned two degrees more upright with less of a cylinder incline, and nearly every component inside the powerplant has been changed to either increase power or improve durability. Another change made to the engine is the new 44mm Mikuni throttle body that replaces the previous Keihn unit. The chassis features an all-new frame and the KYB SSS front fork and rear shock have updated settings to work with the layout of the bike. The bodywork is noticeably different, especially the airbox and radiator shrouds, which are slimmer than the previous generation model. Lastly, Yamaha developed an app for iOS and Android devices that allows the user to change the fuel and ignition timing without the use of a GYTR Power Tuner.

Beginning with the engine, the new electric start system worked flawlessly during our first full day of testing. The engine can be fired to life regardless of whether the clutch is engaged or disengaged and whether the bike is in gear or not. The power delivery is a bit smoother than the previous generation machine and the power characteristics of the new engine make it feel more usable and easier to control. When exiting corners, the bike doesn’t feel like it wants to jump out from underneath you and at the same time, feels like it’s getting more traction because the rear wheel isn’t spinning due to excessive amounts of power being put to the ground.

Yamaha was able to increase the power output of the new engine by three horsepower in the mid-range and top end - more specifically at 6,000 and 9,000 rpm. This was noticeable right away, especially on the long start straight at Glen Helen. Also, the engine mounting and more upright cylinder angle makes the bike feel more balanced overall. The bike has a more centered feeling, which makes the bike more comfortable and predictable in high speed areas, corners, and tight sections.

While the power delivery is unquestionably smooth, we wanted to see if we could soften the bottom end hit to make tighter corners easier to manage. While we noticed how smooth the powerband was in the early morning when the track was smooth, the bottom end power became a little more difficult to manage in the deeply rutted corners. We created a custom map that had a richer fuel delivery off the bottom end between 2,000 and 4,000 rpm. This did exactly what it we wanted it to as the bike was easier to control in tight corners with deep ruts, especially when exiting a turn. It had more of a user friendly feeling when rolling on the power and fatigued our test riders less because the bottom end hit was slightly less abrupt in the rougher, more challenging track conditions.

In the suspension department, we are pleased to say that the KYB SSS front fork and rear shock are as great as ever. Both ends are super plush and offer plenty of comfort in braking bumps, but also absorb the big impacts excellently. Our pro test rider, Nick Evennou, made zero changes to the suspension all day after setting his sag at 104mm in the morning. Meanwhile, Associate Editor Andrew Oldar, who is a novice-level motocross rider, set his sag at 100mm and went two clicks softer on the compression in both the front and rear. This allowed the bike to settle more in corners and help it sit lower in the stroke as well. This also allowed the bike absorb bigger impacts, which are common in the late afternoon at Glen Helen.

The new chassis makes the bike have more of a 250F-esque feeling on the track. It feels more lightweight and nimble, and both of our test riders commented on how they were able to throw it around a lot easier than the previous model. Evennou mentioned that the bike seemed to adapt with him as opposed to working against him, like the older YZ450F sometimes did. As the track got rougher throughout the day, both test riders were able to find different lines a lot easier and put the bike where they wanted to. The overall feel of the 2018 machine is unquestionably a world of difference in comparison to the 2017 model.

A minor but very noticeable change for 2018 are the bar clamps which are mounted higher for 2018. Evennou commented that it was the first thing he noticed when he sat on the bike. The higher mounts made the bike feel like it had more of a chopper setup, and both of our test riders opted to roll the bars back a little further than they would on the previous generation YZ450F.

The new bodywork is noticeable immediately after swinging a leg over the bike. The new radiator shrouds are a night and day difference from the previous generation model in terms of how slim they are, both visually and when riding the bike. Because of this, it feels much skinner between your knees, especially when extending your leg out when cornering.

Overall, we are very pleased with the changes made to the 2018 Yamaha YZ450F. The engine is stronger than ever and the power delivery is smooth, which makes the bike easy to ride. The new chassis contributes to a lighter and more nimble feel and the new bodywork makes the bike more comfortable and easier to corner. As in years past, the suspension is top notch in terms of comfort, plushness, and overall bottoming resistance. We like the fact that we don’t need an extra tool to make fuel and ignition timing changes and can do so from our smartphones via Yamaha’s Power Tuner app. We will be putting several more hours on this bike with a slew of test riders of varying skill levels at different tracks to see how the 2018 Yamaha YZ450F performs under a variety of different conditions.