Electric dirt bikes are rapidly transforming the motocross landscape, igniting excitement within the industry. While groundbreaking models like the Stark VARG and Flux Primo are capturing headlines, the absence of major manufacturers like Honda, Yamaha, and KTM in the full-size electric dirt bike market leaves enthusiasts eager for more. The legacy of Alta’s innovative spirit persists, fueling the anticipation for electric advancements from established brands.
Amidst this forward momentum, a valuable perspective often overlooked is the wealth of refined chassis technology developed over decades by leading engineers, riders, and racers. These proven platforms are ideally suited for electric conversions. Fortunately, a growing number of companies are venturing into this space, creating electric conversion kits compatible with some of the most celebrated motocross bikes ever produced.
One such innovator is Xtreme Electric MX (XEMX), and their Yamaha XE4 Electric Dirt Bike stands out as a compelling example of this approach. Following several successful electric conversions, the XE4 Yamaha from XEMX has captured significant attention. The impressive performance of JoJo Toole on this bike at the 2022 ECR eMoto Race during the Red Bull TKO event further solidified its appeal and sparked considerable interest within the electric motocross community.
Jojo Toole expertly maneuvers the Yamaha XE4 electric motocross bike during the 2022 Redbull TKO ECR eMoto race, showcasing the bike's agility and performance in a competitive environment.
Decoding the XEMX Yamaha XE4 Electric Dirt Bike: Specifications and Features
XEMX offers two distinct conversion kits: the XE2 (air-cooled) and the XE4 (liquid-cooled). The XE4, a liquid-cooled system, is designed as a bolt-on conversion kit compatible 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 riders to electrify existing, well-regarded Yamaha motocross bikes.
The liquid-cooled XE4 system cleverly utilizes the stock Yamaha YZF radiators, incorporating a small 12v pump to circulate Engine Ice coolant. Liquid cooling is crucial for maintaining optimal motor temperature, directly enhancing the XE4’s efficiency and overall performance by preventing overheating. A standout feature of the XE4 is XEMX’s proprietary fast-change battery swap technology, engineered for rapid battery replacement. This system boasts the fastest battery swap time currently available, enabling a complete battery change in under 10 seconds, minimizing downtime and maximizing riding time.
The Yamaha XE4 model used for testing is based on a 2016 Yamaha YZ250F chassis. XEMX currently employs a 12T front and 52T rear sprocket configuration, with occasional adjustments to a 12T-54T combination depending on riding conditions and rider preference. Notably, the bike retains stock Yamaha components for sprockets, plastics, suspension, and grips, ensuring familiar handling and readily available replacement parts. The front sprockets are standard YZF450 parts, further emphasizing the use of proven Yamaha components.
XEMX is actively evaluating various motor controllers to identify the optimal unit for overall performance. Controllers under consideration include the Curtis 1236SE, Votol EM-260S, EBMX X-9000, Fardriver, Kelly, and the A5, a Curtis clone. Rigorous racing tests are planned for each controller to determine the best option for the XE4, guaranteeing peak performance and reliability in demanding motocross environments. During testing, the showcased bike utilized the Curtis 1236SE controller, rated at 450 amps at 72 volts.
Close-up view of the Yamaha XE4 electric motocross bike's motor and cooling system, highlighting the integration of liquid cooling and the compact design of the electric powertrain within the Yamaha chassis.
XEMX’s custom-designed batteries are rated at 72V nominal with a substantial 600 Amp maximum output, providing a total capacity of 4.3kWh. The custom nature of these batteries allows XEMX to tailor the cell type and quantity to meet specific customer requirements, offering flexibility in performance and range.
The proprietary fast-change battery swap system from XEMX utilizes a modified aerospace connector, capable of handling 600 amps per terminal. The battery compartment ingeniously repurposes the original Yamaha YZF gas cap lid, resulting in a clean and user-friendly design. The battery swap process is remarkably quick, consistently achieved in under 10 seconds, a crucial advantage for competitive riding and extended trail sessions.
Demonstration of the Yamaha XE4's fast battery swap system, illustrating the speed and ease of replacing the battery pack in under 10 seconds, a key feature for electric motocross.
The XE4 offers a range of customizable riding modes, all fully programmable to suit diverse terrains and rider preferences. Additional features include reverse functionality, automatic regenerative braking, and optional lever-activated regenerative braking for enhanced control and energy efficiency. A unique and intriguing option is the inclusion of motor sounds via a speaker system, a feature rarely encountered in electric motorcycles, allowing riders to customize their auditory experience.
Detailed view of the Yamaha XE4's programmable control panel and ride mode selector, showing the user interface for adjusting performance settings and engaging features like reverse and regenerative braking on the electric motocross bike.
Currently, the XEMX Yamaha XE4 is built to custom order, but plans are in place to offer conversion kits for general sale upon completion of beta testing. These kits will provide enthusiasts with the components needed to transform their existing Yamaha bikes into high-performance electric motocross machines.
Riding the Yamaha XE4 Electric Dirt Bike: Performance and Handling
While experiences with the Stark VARG and Alta Redshift have been notable, the Electric Cycle Rider (ECR) team frequently utilizes the KTM Freeride EXC and smaller, modified electric dirt bikes like the Sur-Ron Light Bee X for regular riding and testing.
The XEMX Yamaha XE4 delivers an exceptional riding experience. The Yamaha YZF chassis has established itself as a highly reliable and respected platform, largely attributed to its innovative reverse motor design, which contributed to unmatched horsepower within the professional MX scene in its gasoline-powered iterations.
Although the electric powertrain replaces the original gasoline engine, the YZF chassis design provides XEMX with an adaptable space to house the electric motor and battery system efficiently. The Yamaha chassis is celebrated for its inherent stability and confidence-inspiring handling, especially in challenging terrain. The highly regarded KYB SSS suspension system, a stock feature on Yamaha YZF bikes, is a major draw for riders seeking premium suspension performance.
Riding the XEMX Yamaha XE4 effectively translates the lauded stability and suspension characteristics of the Yamaha YZF chassis into the electric realm. The bike feels remarkably planted and composed, particularly when compared to lighter sub-150-pound electric dirt bikes that often struggle in rough, sandy whoop sections commonly found in regions like Florida. The riding sensation closely mirrors that of a Yamaha YZF250F, but with the instant torque and silent operation of an electric powertrain – a highly desirable combination for many riders.
One frequently discussed characteristic of the YZF chassis is its slight trade-off of front-end steering sharpness for enhanced stability. It is often described as a bike that rewards riders who “steer with the rear,” appealing to those who prioritize stability over the razor-sharp turning capabilities of bikes like KTM, Suzuki, or Honda. However, these are minor nuances, and adjustments can be made to fine-tune the turning characteristics and front-end feel of the YZF chassis to suit individual riding styles.
During video testing of the Yamaha XE4 electric dirt bike, a minor issue was encountered. Under hard throttle input when hitting sand whoops aggressively, the bike occasionally faulted. Mark from XEMX clarified that this was due to a slight misalignment between the sensor and magnet in the motor, causing intermittent shutdowns. This is a known potential issue in new motor designs, and XEMX has since resolved this problem in 99% of cases, attributing the remaining instances to older connector types. Importantly, this issue is being fully addressed before the kits are released for sale.
In practical field adjustments during testing, XEMX dialed back the power output by approximately 20%. This meant the bike was operating at only 80% of its potential power during the review. The tested controller was rated for 450 Amps, while the batteries are capable of delivering up to 600 Amps. This indicates significant untapped power potential within the XE4 platform, suggesting future performance enhancements are readily achievable with controller upgrades and further refinements.
Action shot of the Yamaha XE4 electric motocross bike tackling a jump, demonstrating the bike's capability and responsiveness on motocross terrain.
XEMX Yamaha XE4 Electric Dirt Bike: Pricing and Kit Options
While XEMX has not yet officially commenced kit sales, they are prioritizing custom Billet motor orders and associated parts for early adopters. With the complete “A kit” and a prepped rolling frame, assembling the XE4 can be accomplished in a single day, streamlining the conversion process for experienced individuals.
To undertake an XE4 conversion, you will need a Yamaha 250 YZF or FX (2014-2019) or 450 YZF (2014-2018) rolling frame as the foundation. XEMX motors feature ceramic bearings and a carbon-sleeved rotor, finished in black (Cerakoting or powder coating is available as an extra option).
Pricing Breakdown:
BILLET 6061 ALUMINUM MOTOR ALONE: $3,500.
XE4 ALL 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, INCLUDING:
- FULLY BUILT BATTERY TRAY, BATTERY SIDE BRACKETS, BUSS BARS, AND PHASE WIRES.
- 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, 12T FRONT SPROCKET, CARBON FIBER AND MID SEAT PAD.
- CURTIS 1236SE-6571 PRE-PROGRAMMED CONTROLLER AND COMPLETE WIRING HARNESS. POWER PANEL, MODE AND ON/OFF SWITCHES.
QUICK SWAP BATTERIES (SOLD SEPARATELY FROM 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 options are also currently available.
OPTIONAL CHARGER: $250.
MODEL S2500 BATTERY CHARGER INPUT: 120V AC VOLT, OUTPUT: 84V=10AMP WITH LED DISPLAY AND FINISH CHARGE INDICATOR. (Higher amp/faster charging options will be offered).
OPTIONAL PROGRAMMER: $695.
HAND HELD PROGRAMMER FOR THE CURTIS SE1236-6571 CONTROLLER.
OPTIONAL SEAT: $250.
CUSTOM SEAT CONCEPTS SEAT COVER DESIGNED FOR THE QUICK SWAP BATTERY SYSTEM.
In conclusion, the Yamaha XE4 Electric Dirt Bike represents a significant step forward in electric motocross technology, seamlessly blending a proven chassis with a potent electric powertrain. For riders seeking a full-size electric motocross bike, the XE4 offers a compelling option, leveraging fast-change battery swap technology and a well-engineered conversion kit. While currently in beta testing, XEMX is dedicated to making these conversion kits commercially available. For further information, contact Mark Peroni at www.xemx1.com or via email at [email protected].
