Yamaha's prototype hybrid motorcycle combines a petrol engine with two electric motors.
Yamaha has developed an innovative petrol-electric hybrid powertrain which could be heading for production in the future.
Yamaha's innovative petrol-electric hybrid powertrain could revolutionise the motorcycle industry. The system combines a conventional engine with two electric motors, allowing various modes from all-electric to maximum acceleration. Classified as a 'series-parallel' hybrid, this is the first application of such technology on two-wheelers. Yamaha is currently developing the SPHEV system for a mid-range scooter, with a prototype based on the XMax. The company has also hinted at integrating this technology into their three-cylinder 890cc CP3 platform.
Yamaha's hybrid powertrain system, known as SPHEV, utilizes an internal combustion engine and two electric motors. The prototype features a 292cc single-cylinder engine from the XMax 300, connected to the rear wheel through a CVT transmission.
The first electric motor, referred to as the 'drive' motor, is aligned with the rear wheel. This motor functions both as a propulsion source, directly applying torque to the wheel, and as a regenerative braking system, charging the battery during coasting or deceleration.
The second electric motor, designated the 'generator' motor, is attached to the petrol engine's crankshaft. Its primary role is to work in conjunction with the combustion engine, generating electricity to recharge the battery.
The hybrid system begins in full-electric mode. The rear drive motor draws energy from the battery to propel the vehicle, and when the throttle is closed, it acts as a generator, recharging the battery. As speed increases, the petrol engine takes over the driving duties through a scooter-style variable transmission. When more power is required, the drive motor and petrol engine work together to provide 'dual boost'. For maximum acceleration, all three power sources - the battery-powered motor, the petrol engine, and the crank-mounted electric motor - operate simultaneously.
From Scooter to Sporty Naked
Yamaha's prototype has been transformed from a conventional step-through scooter into a radical-looking urban runabout. The space for the rider's legs has been filled by the hybrid system's battery, inverter and control unit. Instead of flat floorboards, the feet now rest on motorcycle-style footpegs, though the rear brake is still operated by a lever on the left handlebar.
Other notable changes include upside-down forks and radially mounted brake calipers, which resemble the TMax more than the XMax. The silencer has also been moved from the right to the left side, likely to accommodate the rear drive motor.
It remains to be seen whether the production-ready model will resemble this unconventional prototype or be closer to a standard scooter design.
Yamaha has signalled the potential for another use of its hybrid technology. The end of the announcement video for the Yamaha SPHEV system featured the words "What's coming next" along with a close-up shot of Yamaha's distinctive 890cc CP3 triple engine.
Differentiating Yamaha's Approach from Kawasaki
Yamaha's hybrid powertrain is a 'series-parallel' design, which combines two distinct approaches to hybrid technology. This effectively results in a hybrid of hybrid systems.
In a 'series' hybrid configuration, the internal combustion engine is solely used to generate electricity, with the wheels always driven by electric motors and never directly by the engine.
In a 'parallel' hybrid system, the combustion engine and electric motors can operate independently or together. Kawasaki's Ninja 7 and Z7 Hybrid bikes use this parallel design, allowing them to run solely on electric power, solely on petrol, or a combination of both.
Yamaha's prototype combines these ideas. The petrol engine can function as a generator or directly drive the rear wheel. This increased flexibility should enable more efficient operation across a broader range of riding conditions, enhancing both fuel economy and performance.
