Yamaha Electric Motocross Bike Evolves

Admin · April 22

Yamaha continues development on its upcoming electric motocross bike. (Yamaha/)

Last month we revealed that Yamaha is developing an electric motocross bike using lessons learned from its TY-E battery-powered trials bike project. Now, additional patents have been published showing further details of the machine and suggesting it’s getting close to completion.

The original patent showed details of the bike’s transmission and how it differed from the TY-E. On the trials bike, Yamaha has retained a conventional clutch despite only needing a single-speed gearbox and combined it with a flywheel that acts as an energy store. Essentially that means you can use the motor to keep the flywheel spinning fast when the clutch is pulled in, then release all the energy stored in that rotating mass in a single thump by dropping the clutch. Alternatively, the torque can be modulated very carefully using the clutch while keeping the flywheel spinning fast to help maintain balance. All ideal for trials riding, but an unnecessary additional weight and complication for a motocross bike.

Yamaha already has an electric trials bike called the TY-E that has some interesting features. (Yamaha/)

The solution, shown in the original patent, is to eliminate the clutch and add a set of springs between the motor and the transmission. These springs act in two ways. First, they slightly soften the immediate response of the electric motor to help prevent jolts through the transmission. Second, like the trials bike’s flywheel, they can be used as a temporary energy store: Slam the throttle open and the springs briefly compress, storing energy, then they extend again to release that energy, which is combined with the motor’s maximum output to give a momentary boost, for instance to help lift the front wheel.

Yamaha’s new patents tackle some more mundane but equally important aspects of the electric motocross bike and include illustrations that look slightly more like a finished machine than the original document.

Top view of Yamaha’s upcoming electric MXer. (Yamaha/)

The first of them relates to the fact that the motocross machine is likely to be exposed to water. The motor, battery, and transmission can be waterproofed to ensure fluid can’t get into them, but there’s also the need for breather hoses from the electronics to cope with pressure changes or to release any condensation that might build up inside the motor, battery case, or control electronics boxes. To this end, Yamaha has added a set of breathers that run up to a point just behind the bike’s steering head—it’s mounted high in case the bike is ridden through deep water—and added a breathable, waterproof cap to the top of it that prevents water getting back in when the bike is pressure washed or somehow submerged.

That means, despite the fact we all know not to mix water and electricity, the electric motocross bike is likely to be better suited to deep wading than a conventional, gasoline motorcycle as there’s no engine intake or exhaust that might allow water into places where it can cause real damage.

Another new patent related to the electric motocross bike shows how Yamaha wants to make sure riders can maximize performance during a race without having to worry about running out of charge before they see the checkered flag. The idea is that, before a race starts, the rider can input the estimated time that the race will take, and based on that data and the amount of charge in the battery the bike will calculate how much performance it can afford to use. Ideally, the battery will be flat at the end of the race, having used all the energy stored in it, but it won’t run out before you cross the finish line. By automating the calculations needed to work out how much power can be used during the race, riders can race flat out without having to manage their own charge levels.

Honda has been racing its prototype electric motocrosser for a few years now. <i>Honda</i>