The electric revolution is charging through the motocross world, with exciting new bikes like the Stark VARG and Flux Primo grabbing headlines. However, the early departure of Alta left a void, leaving enthusiasts wondering when established giants like Honda, Yamaha, and KTM would fully commit to the electric dirt bike market. While we wait for these manufacturers to unveil their all-electric models, a different approach is gaining traction: electric conversion kits. These kits allow riders to breathe new, silent, and powerful life into existing, proven motocross chassis.
It’s easy to get caught up in the hype of entirely new electric bike designs. But let’s not forget the decades of engineering and refinement poured into the chassis of gasoline-powered motocross bikes. These chassis, honed by the best minds and riders in the industry, are prime candidates for electric transformation. Fortunately, companies are emerging to fill this niche, creating electric conversion kits that seamlessly integrate with some of the most respected motocross platforms available.
Enter Xtreme Electric MX (XEMX) and their Yamaha XE4 Electric Dirt Bike conversion kit.
Having witnessed several successful electric conversions, the XE4 Yamaha from XEMX has truly captured our attention. Our interest was sparked by JoJo Toole’s impressive performance on the XE4 during the ECR eMoto Race at the 2022 Red Bull TKO. This performance demonstrated the real-world potential of converting a Yamaha into a high-performance electric dirt bike.
Jojo Toole showcasing the power of the Yamaha electric dirt bike conversion kit in the 2022 Redbull TKO ECR eMoto race.
XEMX Yamaha Electric Dirt Bike Specifications and Features
XEMX offers two distinct conversion kits: the XE2 (air-cooled) and the XE4 (liquid-cooled). While both offer a path to electric motocross, the XE4, with its liquid cooling, represents the pinnacle of their current technology and the focus of this article.
The XE4 is designed as a bolt-on conversion kit, engineered for compatibility with Yamaha 250 and 450 YZF and YZFX models. Specifically, it fits 250 chassis from 2014-2019 and 450 chassis from 2014-2018. This broad compatibility allows owners of popular Yamaha motocross bikes to easily transition to electric power without needing a completely new machine.
The liquid-cooled system on the XE4 leverages the stock Yamaha YZF radiators, supplemented by a small, efficient 12V pump to circulate Engine Ice coolant. Liquid cooling is critical for maintaining optimal motor temperature. A cooler motor translates directly to increased efficiency and sustained performance, especially under the demanding conditions of motocross riding.
A standout feature of the XE4 is XEMX’s proprietary fast-change battery swap technology. This system boasts the fastest battery swap on the market, allowing for a complete battery change in under 10 seconds. This rapid swap capability is a game-changer for electric dirt bikes, addressing a key concern about range and downtime.
The Yamaha XE4 we tested was built upon a 2016 Yamaha YZ250F chassis. XEMX currently utilizes a 12T front and 52T rear sprocket combination, with options to adjust to a 12T-54T setup depending on rider preference and track conditions. Importantly, the bike retains stock Yamaha components for parts like sprockets, plastics, suspension, and grips, ensuring readily available replacements and maintaining the familiar Yamaha feel. Front sprockets are even sourced from the stock YZF450, further emphasizing parts commonality.
XEMX is actively engaged in testing various controllers to pinpoint the ideal unit for overall performance. Controllers under evaluation include the Curtis 1236SE, Votol EM-260S, EBMX X-9000, Fardriver, Kelly, and the A5 (a Curtis clone). Rigorous racing tests are being conducted to determine which controller delivers the best balance of power, efficiency, and reliability for the Yamaha Electric Dirt Bike conversion.
The Curtis 1236SE controller, rated at 450 amps at 72 volts, was the specific controller used in our test bike. This provides a robust power delivery and is a well-regarded option in the electric vehicle controller space.
XEMX’s custom-designed batteries are rated at 72V nominal with a substantial 600 Amp max output and a total capacity of 4.3kWh. The custom nature of the batteries allows XEMX to tailor the cell type and quantity to meet specific customer requirements, optimizing for either range or peak power depending on riding style and needs.
The proprietary fast-change battery swap system utilizes a modified aerospace connector, capable of handling a massive 600 amps per terminal. The battery compartment cleverly repurposes the stock Yamaha YZF gas cap lid, resulting in a clean and user-friendly design. The sub-10-second battery swap time is achieved through this innovative and robust system.
The Yamaha XE4 electric dirt bike features three fully programmable ride modes, allowing riders to customize the power delivery to suit varying terrain and skill levels. Additional features include reverse functionality, automatic regenerative braking, and options for lever-activated regenerative braking. A unique and somewhat unexpected feature is the optional motor sounds, delivered through a speaker system. This provides an auditory element to the electric riding experience, something not commonly found on electric dirt bikes.
Currently, the XEMX Yamaha XE4 is built to custom order as part of their beta testing phase. However, XEMX plans to make the conversion kits available for general sale once beta testing is complete and any final refinements are implemented.
Riding the Yamaha XE4 Electric Dirt Bike
Our team has experience riding other notable electric dirt bikes like the Stark VARG and Alta Redshift. We also frequently ride the KTM Freeride EXC and smaller modified electric bikes like the SurRon Lightbee X. This diverse experience provides a strong basis for comparison when evaluating the Yamaha XE4.
The XEMX Yamaha XE4 delivers an exceptional riding experience. The Yamaha YZF chassis has earned a stellar reputation over the years, particularly noted for its unique reverse motor design in its gasoline-powered form, which contributed to class-leading horsepower.
While the gasoline engine is replaced by the electric powertrain in the XE4, the original chassis design is maintained. This allows XEMX to effectively utilize the existing engine bay space for the electric motor and battery pack, capitalizing on Yamaha’s proven frame geometry and handling characteristics.
The Yamaha chassis is widely praised for its stability and planted feel, especially in challenging terrain. The stock KYB SSS suspension is highly sought after by riders of all levels and comes standard on Yamaha YZF bikes. By retaining this suspension and chassis, the XE4 inherits these desirable handling traits.
Riding the XEMX Yamaha XE4 truly lives up to the hype surrounding the Yamaha YZF chassis’s stability and suspension prowess. The bike feels remarkably planted and confident, especially when compared to lighter sub-150-pound electric dirt bikes that can struggle in rough terrain like the sandy whoops common in Florida riding areas. The experience is remarkably similar to riding a Yamaha YZF250F, but with the instant torque and silent operation of an electric powertrain – a genuinely positive attribute.
If there’s any commonly cited characteristic of the YZF chassis that could be considered a drawback, it’s a slight trade-off of front-end steering sharpness for enhanced stability. YZF chassis bikes are often favored by riders who “steer with the rear” and prioritize stability over razor-sharp turning, unlike bikes from KTM, Suzuki, or Honda, which are known for quicker turning. However, this is a minor point, and adjustments to setup can be made to fine-tune the turning characteristics and front-end feel of the YZF chassis to suit individual preferences.
During our video testing of the Yamaha XE4 electric dirt bike, we encountered a minor issue. The bike would occasionally fault and cut power when hitting sand whoops aggressively with the throttle wide open. Mark from XEMX identified the cause as a slight misalignment between the sensor and magnet in the motor. This intermittent shut-off issue is not uncommon in new motor designs, and XEMX has since resolved the problem in 99% of cases, attributing the remaining instances to older style connectors. XEMX assures that this issue will be fully resolved before the kits are released for sale.
In the field, during our testing, Mark from XEMX made adjustments by reducing the power output by approximately 20%. Effectively, we were only using 80% of the available power during our initial test ride. The controller we tested was rated for 450 Amps, while the batteries are capable of delivering up to 600 Amps. This clearly indicates significant untapped power potential within the XE4 platform.
XEMX Yamaha XE4 Electric Dirt Bike Pricing
XEMX has not yet officially commenced kit sales, but is initially offering custom billet motors on a made-to-order basis, along with the necessary components for early adopters. With their complete “A kit” and a prepped rolling frame, XEMX states that bike assembly can be accomplished in a single day.
To utilize the XE4 conversion, you will need to supply a Yamaha 250 YZF or FX (2014-2019) or 450 YZF (2014-2018) rolling frame.
The motors feature ceramic bearings throughout and a carbon-sleeved rotor, finished in black as standard. (Cerakoting or powder coating is available at an additional cost).
BILLET 6061 ALUMINUM MOTOR ALONE: $3,500.
XE4 BILLET AXIAL FLUX MOTOR WITH CARBON FIBER SLEEVED ROTOR, LIQUID COOLED, CERAMIC BEARING, 2.08 TO 1 GEAR REDUCTION. MAX RATING OF 58 HP. @ 600 AMPS NOMINAL 38 HP.
COMPLETE MOTOR A KIT: $6,995.
XE4 BILLET MOTOR AND KIT, WHICH INCLUDES: 1-3
#1 COMPLETELY BUILT BATTERY TRAY, BATTERY SIDE BRACKETS, BUSS BARS AND
PHASE WIRES.
#2 BRACKETS, FRONT, MID AND TWO REAR SEAT BRACKETS CARBON FIBER AIR BOX
COVER, SEVEN PIVOT POINT HINGE, HALL THROTTLE, WATER PUMP, MAIN CONTACTOR,
DC TO DC CONVERTER,12 T FRONT SPROCKET, CARBON FIBER AND MID SEAT PAD.
#3 CURTIS 1236SE-6571 PRE PROGRAMMED CONTROLLER AND COMPLETE WIRING
HARNESS. POWER PANEL, MODE AND ON/OFF SWITCHES.
QUICK SWAP BATTERIES SOLD SEPARATELY FROM THE KIT: $3,295.
INR 25R SAMSUNG (400) 18650 CELL BATTERY 500 AMP PEAK AT 84V 4KW
10 MODULES (40 18650 CELLS EACH) MOLICEL P42 and P45 Available now also.
OPTIONAL CHARGER: $250.
MODEL S2500 BATTERY CHARGER INPUT: 120V AC VOLT
OUTPUT: 84V=10AMP WITH LED DISPLAY AND FINISH CHARGE INDICATOR.
(OTHER CHARGER OPTIONS WILL BE AVAILABLE (HIGHER AMP/FASTER CHARGING)
OPTIONAL PROGRAMMER: $695.
HAND HELD PROGRAMMER FOR THE CURTIS SE1236-6571 CONTROLLER
OPTIONAL SEAT: $250.
CUSTOM SEAT CONCEPTS SEAT COVER FOR QUICK SWAP BATTERY SYSTEM.
In conclusion, the Yamaha XE4 Electric Dirt Bike conversion kit represents a compelling and innovative approach to electric motocross. By leveraging the proven Yamaha YZF chassis and incorporating a powerful electric powertrain with proprietary fast-change battery technology, the XE4 offers a thrilling glimpse into the future of off-road riding. For riders eager to experience the electric advantage in a full-size motocross package, the Yamaha XE4 is definitely worth exploring.
While still in the beta testing phase, XEMX is actively working towards making these conversion kits commercially available. For those seeking further information or wishing to inquire about custom orders, you can contact Mark Peroni directly through their website at www.xemx1.com or via email at [email protected].
