XEMX makes two separate conversion kits (the air-cooled XE2 and liquid-cooled XE4) for Yamaha's YZ250F and YZ450F dirt bikes, but the brand is currently only accepting pre-orders for the XE4 model. These are also year-specific, as only 2014–2019 models for the YZ250F and 2014–2018 models for the YZ450F are compatible with these bolt-on kits as of now.

The Yamaha YZF has been a solid platform in pro-MX over the years, owing to its special reverse motor configuration that generates power unrivaled by other manufacturers. In the kit, the IC motor of Yamaha dirt bikes is swapped out with the XE4 engine. It comes with a 12-volt pump for pumping coolant to keep the electric motor cool using the stock YZF radiator, and XEMX reckons it's a one-day job.

In addition, the XE4 has a unique fast-change battery swap system that gets the pack in and out in a matter of seconds if you want to stay out on the trails.

These 72-volt battery packs can deliver up to 600 amps and 4.3 kWh. XEMX doesn't give a range or endurance estimate, but we know the wild, barnstorming Stark Varg gets up to 6 hours out of its 6.5 kWh pack, so it seems reasonable to assume that the XE4 will last over four hours of riding if treated gently.

Not that you'd be treating it gently. With an output of 58 hp, you're barely losing any peak power compared to the 59-hp 2023 Yamaha YZ450F – and anyone who's ridden an electric will know the torque will be instant and epic. It has an "axial flux motor" that runs on a "carbon fiber sleeved rotor" and ceramic bearing.

The bike features three completely customizable ride modes, lever regen braking, auto regen braking, as well as a reverse 'gear.' There's also an optional speaker that'll supply some fake engine sounds if you find the whirr of the electric motor a tad uninspiring.