There's little doubt that electric dirt bikes will eventually replace gas-powered ones, much like four-strokes replaced two-strokes. The XE4 by Xtreme Electric MX (XEMX) is a bolt-on kit that converts Yamaha 250 and 450 YZF/YZFX bikes to high-powered electrics.
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.
XEMX offers the Complete Motor A Kit for US$6,995 and the Quick Swap Batteries for US$3,295 apiece. Preorders for the XE4 Complete Custom Bikes are also open in addition to the electric conversion kits. The complete bikes will cost you around US$12,950. They are available in blue and gray colors.
How do they go? In April of this year, Shawn Clark took first place in 30+ and 7th overall in the Daytona Dirt Riders Alligator Hair Scramble riding the XE4. Then in the following month, XE4 secured first place at the GNCC Wild Boar 2024 E-Open Class. It’s safe to say that the electric bike is a capable machine.
The real question left to be answered is if the motocross scene will see the entry of electric dirt bikes like the XE4. While most IC enthusiasts will shake their heads at the thought of it, we think it’s not a matter of if, but when. Much like four-strokes did for the older two-stroke models, it's almost a given that EVs are the next step.
It’s only natural - as electric dirt bikes become more and more race ready, race sanctioning authorities, promoters, and even riders will jump on the electric bandwagon. Who knows, it might also help local motocross tracks avoid closure due to noise concerns. For now, though, the current crop of motocross bikes remain the noisy, gas guzzling works of art that we know and love.
Source: XEMX
